Early this morning I received some notifications of earthquakes along the Tonga trench (southwestern central Pacific Ocean). It was about 2am my local time.
I work on the tsunami program for the California state tsunami program (CTP) and we respond to tsunami to (1) help local communities do their first response activities so that they can help reduce suffering and to (2) document the impact of these tsunami.
Because of this work, our team is “at the ready” 24 hours a day, 7 days a week, to respond to these events. Luckily, this event was unlikely to generate a tsunami that would impact California. I went back to sleep.
This morning I put together a report and checked to see if there was a tsunami generated. Here is one place that I check for tsunami records as observed on tide gages http://www.ioc-sealevelmonitoring.org/map.php. I did not see anything convincing.
This earthquake, from last night my time, has a magnitude of M 7.3.
https://earthquake.usgs.gov/earthquakes/eventpage/us7000ip0l/executive
This area of the Earth has a plate boundary fault system called a subduction zone. A subduction zone is a convergent plate boundary, which means that the plates on either side of the boundary move towards each other.
Here, the Pacific plate dives westwards beneath the Australia plate, forming the Tonga trench. Below is a schematic illustration showing what these plates may look like if we cut into the Earth and viewed this subduction zone from the side. Note the Pacific plate on the right and the Australia plate on the left, with the megathrust subduction zone fault where they meet.
This illustration shows where earthquakes may happen along this plate boundary. There could be interface earthquakes along the megathrust fault (megathrust earthquakes). These are what most people are familiar with when they are thinking about tsunami (e.g., the 2011 Great East Japan Earthquake and Tsunami).
In the upper plate (the Australia plate), there can be crustal fault earthquakes. In the lower plate (the Pacific plate) there can be slab earthquakes (events within the crust, aka the slab), and there can be outer rise earthquakes).
The outer rise is a part of the plate that is warping up and down because of the forces adjacent to the subduction zone. This warping can cause extension in the upper part, and compression in the lower part, of this plate.
This 11 Nov 2022 M 7.3 earthquake was a compressional (reverse) earthquake in the outer rise region of this plate boundary. It was pretty deep (for oceanic crust) so fits nicely in the correct place in this illustration:
But megathrust earthquakes are not the only type of earthquake that can cause a tsunami. The 2009 magnitude M 8.1 extensional (normal) fault earthquake near Samoa and American Samoa caused a tsunami that inundated the nearby islands (causing lots of damage and human suffering). This tsunami also travelled across the Pacific Ocean to impact California! (This is why the California Tsunami Program monitors tsunami across the Pacific Basin, so that we can help reduce suffering through the evacuation of coastal areas. Remember, the entire coast of California is a Tsunami Hazard Area.)
Below is my interpretive poster for this earthquake
- I plot the seismicity from the past month, with diameter representing magnitude (see legend). I include earthquake epicenters from 1922-2022 with magnitudes M ≥ 7.0 in one version.
- I plot the USGS fault plane solutions (moment tensors in blue and focal mechanisms in orange), possibly in addition to some relevant historic earthquakes.
- A review of the basic base map variations and data that I use for the interpretive posters can be found on the Earthquake Reports page. I have improved these posters over time and some of this background information applies to the older posters.
- Some basic fundamentals of earthquake geology and plate tectonics can be found on the Earthquake Plate Tectonic Fundamentals page.
- In the upper left corner is a map that shows the plates, their boundaries, and a century of seismicity.
- In the lower right corner is a map that shows the ground shaking from the earthquake, with color representing intensity using the Modified Mercalli Intensity (MMI) scale. The closer to the earthquake, the stronger the ground shaking. The colors on the map represent the USGS model of ground shaking. The colored circles represent reports from people who posted information on the USGS Did You Feel It? part of the website for this earthquake. There are things that affect the strength of ground shaking other than distance, which is why the reported intensities are different from the modeled intensities.
- To the left is a plot that shows how the shaking intensity models and reports relate to each other. The horizontal axis is distance from the earthquake and the vertical axis is shaking intensity (using the MMI scale, just like in the map to the right: these are the same datasets).
- Further to the left is a diagram that shows the different types of earthquakes that can occur along a subduction zone.
- In the upper right corner is a map that shows some of the historic earthquakes in the region, with the earthquake mechanisms. I labeled these events for the type of event that I interpret them to be.
- In the upper left center is a map from Richards et al. (2011) that shows earthquake locations (epicenters) with color representing depth. I place a yellow star in the general location of today’s M 7.3 earthquake. These colors help us visualize how the Pacific plate dips deeper towards the left (yellow are shallow events and purple are deep events). The 2000.01.08 M 7.2 earthquake is an intermediate depth earthquake (see the map in the upper right corner).
- In the right center is a map from Timm et al (2013) that also shows the depth to the slab (the downgoing Pacific plate). I place a yellow star in the general location of today’s M 7.3 earthquake.
I include some inset figures. Some of the same figures are located in different places on the larger scale map below.
- Well, I just looked at Pago Pago and the record is clear. I am kinda surprised since this gage is on the nodal plane for this event. I will plot these data up.
- Here is a screenshot:
- Here are the two plots for the gages listed above. The Pago pago record is quite clear. However, the Nukualofa gage is pretty noisy. I don’t have much confidence in the measurements of the wave size.
- Data from both gages show a background wave sequence that makes it difficult to know when the tsunami ends. Someone who can filter out that wave series could probably do a better job at locating when the tsunami ends, at least for the Pago Pago data.
- Pago Pago (American Samoa) https://webcritech.jrc.ec.europa.eu/SeaLevelsDb/Device/959
- Nukualofa (Tonga Island) https://webcritech.jrc.ec.europa.eu/SeaLevelsDb/Device/950
Other Report Pages
Some Relevant Discussion and Figures
- Here is the map from Timm et al., 2013.
Bathymetric map of the Tonga–Kermadec arc system. Map showing the depth of the subducted slab beneath the Tonga–Kermadec arc system. Louisville seamount ages are after Koppers et al.49 ELSC, eastern Lau-spreading centre; DSDP, Deep Sea Drilling Programme; NHT, Northern Havre Trough; OT, Osbourn Trough; VFR, Valu Fa Ridge. Arrows mark total convergence rates.
- Here is the oblique view of the slab from Green (2003).
Earthquakes and subducted slabs beneath the Tonga–Fiji area. The subducting slab and detached slab are defined by the historic earthquakes in this region: the steeply dipping surface descending from the Tonga Trench marks the currently active subduction zone, and the surface lying mostly between 500 and 680 km, but rising to 300 km in the east, is a relict from an old subduction zone that descended from the fossil Vitiaz Trench. The locations of the mainshocks of the two Tongan earthquake sequences discussed by Tibi et al. are marked in yellow (2002 sequence) and orange (1986 series). Triggering mainshocks are denoted by stars; triggered mainshocks by circles. The 2002 sequence lies wholly in the currently subducting slab (and slightly extends the earthquake distribution in it),whereas the 1986 mainshock is in that slab but the triggered series is located in the detached slab,which apparently contains significant amounts of metastable olivine
- Here are figures from Richards et al. (2011) with their figure captions below in blockquote.
- The main tectonic map
- Here is the map showing the current configuration of the slabs in the region.
- This is the cross section showing the megathrust fault configuration based on seismic tomography and seismicity.
- Here is their time step interpretation of the slabs that resulted in the second figure above.
bathymetry, and major tectonic element map of the study area. The Tonga and Vanuatu subduction systems are shown together with the locations of earthquake epicenters discussed herein. Earthquakes between 0 and 70 km depth have been removed for clarity. Remaining earthquakes are color-coded according to depth. Earthquakes located at 500–650 km depth beneath the North Fiji Basin are also shown. Plate motions for Vanuatu are from the U.S. Geological Survey, and for Tonga from Beavan et al. (2002) (see text for details). Dashed line indicates location of cross section shown in Figure 3. NFB—North Fiji Basin; HFZ—Hunter Fracture Zone.
Map showing distribution of slab segments beneath the Tonga-Vanuatu region. West-dipping Pacifi c slab is shown in gray; northeast-dipping Australian slab is shown in red. Three detached segments of Australian slab lie below the North Fiji Basin (NFB). HFZ—Hunter Fracture Zone. Contour interval is 100 km. Detached segments of Australian plate form sub-horizontal sheets located at ~600 km depth. White dashed line shows outline of the subducted slab fragments when reconstructed from 660 km depth to the surface. When all subducted components are brought to the surface, the geometry closely approximates that of the North Fiji Basin.
Previous interpretation of combined P-wave tomography and seismicity from van der Hilst (1995). Earthquake hypocenters are shown in blue. The previous interpretation of slab structure is contained within the black dashed lines. Solid red lines mark the surface of the Pacifi c slab (1), the still attached subducting Australian slab (2a), and the detached segment of the Australian plate (2b). UM—upper mantle;
TZ—transition zone; LM—lower mantle.
Simplified plate tectonic reconstruction showing the progressive geometric evolution of the Vanuatu and Tonga subduction systems in plan view and in cross section. Initiation of the Vanuatu subduction system begins by 10 Ma. Initial detachment of the basal part of the Australian slab begins at ca. 5–4 Ma and then sinking and collision between the detached segment and the Pacifi c slab occur by 3–4 Ma. Initial opening of the Lau backarc also occurred at this time. Between 3 Ma and the present, both slabs have been sinking progressively to their current position. VT—Vitiaz trench; dER—d’Entrecasteaux Ridge.
- Here is the tectonic map from Ballance et al., 1999.
Map of the Southwest Pacific Ocean showing the regional tectonic setting and location of the two dredged profiles. Depth contours in kilometres. The presently active arcs comprise New Zealand–Kermadec Ridge–Tonga Ridge, linked with Vanuatu by transforms associated with the North Fiji Basin. Colville Ridge–Lau Ridge is the remnant arc. Havre Trough–Lau Basin is the active backarc basin. Kermadec–Tonga Trench marks the site of subduction of Pacific lithosphere westward beneath Australian plate lithosphere. North and South Fiji Basins are marginal basins of late Neogene and probable Oligocene age, respectively. 5.4sK–Ar date of dredged basalt sample (Adams et al., 1994).
- Here is a great summary of the fault mechanisms for earthquakes along this plate boundary (Yu, 2013).
Large subduction-zone interplate earthquakes (large open gray stars) labeled with event date, Mw, GCMT focal mechanisms, and GPS velocity vectors (gray arrows and black triangles labeled with station name). GPS velocities are listed in Table 3. Black lines indicate the Tonga–Kermadec and Vanuatu trenches. Note that the 2009/09/29 Samoa–Tonga outer trench-slope event (Mw 8.1) triggered large interplate doublets (both of Mw 7.8; Lay et al., 2010). The Pacific plate subducts westward beneath the Australian plate along the Tonga–Kermadec trench, whereas the Australian plate subducts eastward beneath the Vanuatu arc and North Fiji basin. The opposite orientation between the Tonga–Kermadec and Vanuatu subduction systems is due to complex and broad back-arc extension in the Lau and North Fiji basins (Pelletier et al., 1998).
Regional map of moderate-sized (mb > 4:7) shallow-focus repeating earthquakes and background seismicity along the (a) Tonga–Kermadec and (b) Vanuatu (former New Hebrides) subduction zones. Shallow repeating earthquakes (black stars) and their available Global Centroid Moment Tensor (GCMT; Dziewoński et al., 1981; Ekström et al., 2003) are labeled with event date and doublet/cluster id where applicable. Colors of GCMT are used to distinguish nearby different repeaters. Source parameters for the clusters and doublets are listed in Tables 1 and 2. Background seismicity is shown as gray dots and large interplate earthquakes (moment magnitude, Mw > 7:3) since 1976 are shown as large open gray stars. Black lines indicate the trench (Bird, 2003) and slab contour at 50-km depth (Gudmundsson and Sambridge, 1998). Repeating earthquake clusters in the (a) T1 and T2 plate-interface regions in Tonga and (b) V3 plate-interface region in Vanuatu are used to study the fault-slip rate ( _d). A regional map of the Tonga–Kermadec–Vanuatu subduction zones is
shown in the inset figure, with the gray dotted box indicating the expanded region in the main figure.
- 2022.11.11 M 7.3 Tonga
- 2022.09.10 M 7.6 Papua New Guinea
- 2021.03.04 M 8.1 Kermadec
- 2021.02.10 M 7.7 Loyalty Islands
- 2019.06.15 M 7.2 Kermadec
- 2019.05.14 M 7.5 New Ireland
- 2019.05.06 M 7.2 Papua New Guinea
- 2018.12.05 M 7.5 New Caledonia
- 2018.10.10 M 7.0 New Britain, PNG
- 2018.09.09 M 6.9 Kermadec
- 2018.08.29 M 7.1 Loyalty Islands
- 2018.08.18 M 8.2 Fiji
- 2018.03.26 M 6.9 New Britain
- 2018.03.26 M 6.6 New Britain
- 2018.03.08 M 6.8 New Ireland
- 2018.02.25 M 7.5 Papua New Guinea
- 2018.02.26 M 7.5 Papua New Guinea Update #1
- 2017.11.19 M 7.0 Loyalty Islands Update #1
- 2017.11.07 M 6.5 Papua New Guinea
- 2017.11.04 M 6.8 Tonga
- 2017.10.31 M 6.8 Loyalty Islands
- 2017.08.27 M 6.4 N. Bismarck plate
- 2017.05.09 M 6.8 Vanuatu
- 2017.03.19 M 6.0 Solomon Islands
- 2017.03.05 M 6.5 New Britain
- 2017.01.22 M 7.9 Bougainville
- 2017.01.03 M 6.9 Fiji
- 2016.12.17 M 7.9 Bougainville
- 2016.12.08 M 7.8 Solomons
- 2016.10.17 M 6.9 New Britain
- 2016.10.15 M 6.4 South Bismarck Sea
- 2016.09.14 M 6.0 Solomon Islands
- 2016.08.31 M 6.7 New Britain
- 2016.08.12 M 7.2 New Hebrides Update #2
- 2016.08.12 M 7.2 New Hebrides Update #1
- 2016.08.12 M 7.2 New Hebrides
- 2016.04.06 M 6.9 Vanuatu Update #1
- 2016.04.03 M 6.9 Vanuatu
- 2015.03.30 M 7.5 New Britain (Update #5)
- 2015.03.30 M 7.5 New Britain (Update #4)
- 2015.03.29 M 7.5 New Britain (Update #3)
- 2015.03.29 M 7.5 New Britain (Update #2)
- 2015.03.29 M 7.5 New Britain (Update #1)
- 2015.03.29 M 7.5 New Britain
- 2015.11.18 M 6.8 Solomon Islands
- 2015.05.24 M 6.8, 6.8, 6.9 Santa Cruz Islands
- 2015.05.05 M 7.5 New Britain
New Britain | Solomon | Bougainville | New Hebrides | Tonga | Kermadec Earthquake Reports
General Overview
Earthquake Reports
Social Media
#EarthquakeReport for M 7.3 #Earthquake along outer rise near the Tonga trench
reverse (compressional) mechanism
south of analogues incl tsunamigenic 2009 M 8.1 (tho that was extensional)https://t.co/gQEdISt9eD
learn more abt regional tectonics herehttps://t.co/eDsUON2Mly pic.twitter.com/DvMnY4rWck
— Jason "Jay" R. Patton (@patton_cascadia) November 11, 2022
#EarthquakeReport for M 7.3 #Earthquake near the Tonga trench
thrust (compressional) earthquake along the outer rise
no #Tsunami observed on tide gages
report here includes my interpretation and a regional tectonic summary:https://t.co/ze2s3bb7Vn pic.twitter.com/2M3SZaYE19
— Jason "Jay" R. Patton (@patton_cascadia) November 11, 2022
The region near todays M7.3 earthquake is incrediblely active due to the high rates of convergence between the Australian and Pacific Plates. Since 1900, 40 M7.5+ earthquakes have been recorded, as well as at least 3 M8+ events. https://t.co/avVOX0LcGH pic.twitter.com/dN9mIrwgwN
— Wendy Bohon, PhD 🌏 (@DrWendyRocks) November 11, 2022
Fri Nov 11 10:48:00 2022 UTC
Mag: 7.5 Depth: 33
Coords: 19.322 S 172.01 W
Location: TONGA ISLANDS REGION* HAZARDOUS TSUNAMI WAVES FROM THIS EARTHQUAKE ARE POSSIBLE WITHIN 300 KM OF THE EPICENTER ALONG THE COASTS OF
NIUE AND TONGA pic.twitter.com/lm1RMEJ0o8— よっしみ~☆🌏 (@yoshimy_s) November 11, 2022
Seismic waves from the Tonga 7.3 #earthquake, as arriving at a @raspishakEQ station of the @GEO3BCN_CSIC educational network in NE Iberia pic.twitter.com/K6YZPQf1JU
— Jordi Diaz Cusi (@JDiazCusi) November 11, 2022
Recent Earthquake Teachable Moment for the M7.3 Tonga earthquake https://t.co/PJBT5jgOTy pic.twitter.com/h0kTCejygS
— IRIS Earthquake Sci (@IRIS_EPO) November 11, 2022
Global surface and body wave sections from the M7.3 earthquake near Tongahttps://t.co/mz6A6vgD9F pic.twitter.com/0psyiRcDum
— IRIS Earthquake Sci (@IRIS_EPO) November 11, 2022
Mw=7.3, TONGA ISLANDS REGION (Depth: 43 km), 2022/11/11 10:48:42 UTC – Full details here: https://t.co/vqxit49tby pic.twitter.com/m16qoCB5wK
— Earthquakes (@geoscope_ipgp) November 11, 2022
Watch the waves from the M7.3 earthquake near Tonga roll across seismic stations in North America (THREAD 🧵) pic.twitter.com/hupVx0WfpQ
— IRIS Earthquake Sci (@IRIS_EPO) November 11, 2022
Section from today's M7.3 earthquake in the Tonga region at 2022-11-11 10:48:45UTC recorded on the worldwide @raspishake network. See: https://t.co/LS1S4JlAqX. Uses @obspy and @matplotlib. pic.twitter.com/Jdz1FlEZN2
— Mark Vanstone (@wmvanstone) November 11, 2022
A cross-section of seismicity, with the focal mechanisms projected into the vertical plane, shows the three deep quakes with purple outlines. These events were close to the deepest quakes in this area, where the subducted slab possibly is deflected by the 670 km discontinuity. pic.twitter.com/V09EYGWJRd
— Jascha Polet (@CPPGeophysics) November 11, 2022
- Frisch, W., Meschede, M., Blakey, R., 2011. Plate Tectonics, Springer-Verlag, London, 213 pp.
- Hayes, G., 2018, Slab2 – A Comprehensive Subduction Zone Geometry Model: U.S. Geological Survey data release, https://doi.org/10.5066/F7PV6JNV.
- Holt, W. E., C. Kreemer, A. J. Haines, L. Estey, C. Meertens, G. Blewitt, and D. Lavallee (2005), Project helps constrain continental dynamics and seismic hazards, Eos Trans. AGU, 86(41), 383–387, , https://doi.org/10.1029/2005EO410002. /li>
- Jessee, M.A.N., Hamburger, M. W., Allstadt, K., Wald, D. J., Robeson, S. M., Tanyas, H., et al. (2018). A global empirical model for near-real-time assessment of seismically induced landslides. Journal of Geophysical Research: Earth Surface, 123, 1835–1859. https://doi.org/10.1029/2017JF004494
- Kreemer, C., J. Haines, W. Holt, G. Blewitt, and D. Lavallee (2000), On the determination of a global strain rate model, Geophys. J. Int., 52(10), 765–770.
- Kreemer, C., W. E. Holt, and A. J. Haines (2003), An integrated global model of present-day plate motions and plate boundary deformation, Geophys. J. Int., 154(1), 8–34, , https://doi.org/10.1046/j.1365-246X.2003.01917.x.
- Kreemer, C., G. Blewitt, E.C. Klein, 2014. A geodetic plate motion and Global Strain Rate Model in Geochemistry, Geophysics, Geosystems, v. 15, p. 3849-3889, https://doi.org/10.1002/2014GC005407.
- Meyer, B., Saltus, R., Chulliat, a., 2017. EMAG2: Earth Magnetic Anomaly Grid (2-arc-minute resolution) Version 3. National Centers for Environmental Information, NOAA. Model. https://doi.org/10.7289/V5H70CVX
- Müller, R.D., Sdrolias, M., Gaina, C. and Roest, W.R., 2008, Age spreading rates and spreading asymmetry of the world’s ocean crust in Geochemistry, Geophysics, Geosystems, 9, Q04006, https://doi.org/10.1029/2007GC001743
- Pagani,M. , J. Garcia-Pelaez, R. Gee, K. Johnson, V. Poggi, R. Styron, G. Weatherill, M. Simionato, D. Viganò, L. Danciu, D. Monelli (2018). Global Earthquake Model (GEM) Seismic Hazard Map (version 2018.1 – December 2018), DOI: 10.13117/GEM-GLOBAL-SEISMIC-HAZARD-MAP-2018.1
- Silva, V ., D Amo-Oduro, A Calderon, J Dabbeek, V Despotaki, L Martins, A Rao, M Simionato, D Viganò, C Yepes, A Acevedo, N Horspool, H Crowley, K Jaiswal, M Journeay, M Pittore, 2018. Global Earthquake Model (GEM) Seismic Risk Map (version 2018.1). https://doi.org/10.13117/GEM-GLOBAL-SEISMIC-RISK-MAP-2018.1
- Zhu, J., Baise, L. G., Thompson, E. M., 2017, An Updated Geospatial Liquefaction Model for Global Application, Bulletin of the Seismological Society of America, 107, p 1365-1385, https://doi.org/0.1785/0120160198
- Richards, S., Holm, R., and Barber, G., 2011. Skip Nav Destination When slabs collide: A tectonic assessment of deep earthquakes in the Tonga-Vanuatu region in Geology, c. 39, no. 8, p. 787-790, https://doi.org/10.1130/G31937.1
- Timm, C., Bassett, D., Graham, I. et al. Louisville seamount subduction and its implication on mantle flow beneath the central Tonga–Kermadec arc. Nat Commun 4, 1720 (2013). https://doi.org/10.1038/ncomms2702
References:
Basic & General References
Specific References
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I don’t always have the time to write a proper Earthquake Report. However, I prepare interpretive posters for these events. Because of this, I present Earthquake Report Lite. (but it is more than just water, like the adult beverage that claims otherwise). I will try to describe the figures included in the poster, but sometimes I will simply post the poster here. https://earthquake.usgs.gov/earthquakes/eventpage/us7000ilwt/executive This is possibly one of the most mysterious earthquakes of the year. I forgot to write this up at the time so need to fill in more details after I am done working up my annual summary.
I will be filling this in over the next few days and wanted to start collating social media materials for this event. There was a large volcanic eruption in the Tonga region. This eruption was observable from satellites and has generated a modest but observable tsunami from Australia to the United States. This event is still unfolding and it will take months until we have a deeper understanding of the causes for the tsunami. We know it is related to the explosive volcanic eruption from Hunga Tonga-Hunga Ha’apai, about 55 kms (35 miles) northwest of the largest island of the Kingdom of Tonga, Tongatapu. I will continue to fill in details. I am currently busy trying to manage our tsunami event response and am learning lots in the process. However, this delays my time available here. This week, CGS sent teams to various harbors & beaches on the California coast to collect measurements, photos, & videos documenting the effects of the Jan. 15 #tsunami from Tonga. This info helps us understand how future tsunami might impact our coastal harbors & communities. pic.twitter.com/xGa8zmNNNs — California Geological Survey (@CAGeoSurvey) January 21, 2022 #Tonga #Tsunami January 15 2022 — California Geological Survey (@CAGeoSurvey) February 2, 2022 After two weeks of work I can finally share my 3D reconstruction of the gigantic ash cloud from the January 15 Hunga #Tonga-Hunga-Ha'apai #eruption Parts likely reached *close to 60km* according to my reconstruction, that's beyond the stratosphere and inside the mesosphere!🧵 pic.twitter.com/qMzPSjZj7P — Simeon Schmauß (@stim3on) February 2, 2022 It is incredible to see how the #Andes bounced back part of the #Tonga atmospheric Lamb wave on its first cross over South America!. Here depicted with signal processed IR data from the GOES 16 geostationary satellite pic.twitter.com/OLM0MD0neO — diego aliaga (@diegoaliaga2) January 28, 2022 Below there are many tweets etc. and one may feel like they are scrolling forever. These tweets are loosely organized into several sections. Excellent thread on how you can best help disaster relief efforts (and why) from someone who knows from professional experience. Donate $ (not 👠s) to reputable relief organizations. This is true for most disaster relief. https://t.co/zj6AIUuCZC — Tim Dawson (@timblor) January 16, 2022 Here's my radio interview on KCBS today.https://t.co/mwAnGWqy59 — Jason "Jay" R. Patton (@patton_cascadia) January 16, 2022 What lies beneath? Revealing the massive Hunga #caldera (5km diameter) below the water line, 3D model using elevation data @theAGU + bathymetrics @NOAA #Tonga #Blender pic.twitter.com/PmpVOfX8HD — frédérik ruys (@fruys) January 16, 2022 This is a truly excellent short article by @LoriDengler about yesterday’s #tsunami and eruption event. It makes it clear just how unique this was, and why the @NWS_NTWC folks had to improvise (brilliantly) to get the alert out. https://t.co/meypb1w2k9 — Harold Tobin (@Harold_Tobin) January 16, 2022 This is a small volcanic island but below the ocean the volcano is huge at around 1.8 km high and 20km wide. Much of the 2014-15 cone is now gone. Read more about what we know by @scronin70: https://t.co/nMNQYGcLDw pic.twitter.com/Ejn3z6e1I4 — Dr Janine Krippner (@janinekrippner) January 15, 2022 Scientists said the volcano had been puffing away for about a month before rising magma, superheated to around 1,000 degrees Celsius (1,832 Fahrenheit), met with 20 degree (68 Fahrenheit) seawater on Saturday, causing an instantaneous and massive explosion pic.twitter.com/iNVC2tB3XM — Reuters (@Reuters) January 19, 2022 An underwater volcano off Tonga erupted on Jan. 15, triggering tsunami warnings and evacuation orders in Japan and causing large waves in several South Pacific islands, where footage on social media showed waves crashing into coastal homes pic.twitter.com/L7uzK59jG7 — Reuters (@Reuters) January 19, 2022 Observations from Japan on why the far-field tsunami was likely triggered by air-sea coupling, not the standard shallow-water wave propagation from the source. https://t.co/70O5V095Xs — Harold Tobin (@Harold_Tobin) January 20, 2022 Why the ocean depth of the Hunga Tonga caldera created the 'sweet spot' that produced such an explosive eruption. Graphic based on research by @scronin70 https://t.co/D8ZBpAQkql pic.twitter.com/3gkDDZIqzm — Alistair Hamill (@lcgeography) January 21, 2022 Lessons from the Tonga Tsunami https://t.co/ZYPy87AzKW — CREW.org (@CascadiaEQ) January 25, 2022 New preprint out on ESSOAr – "Tonga eruption triggered waves propagating globally from surface to edge of space" – in which we look at the deeply unusual atmospheric waves generated by the recent Hunga Tonga eurption. pic.twitter.com/IJfMgb1Bt9 — Corwin Wright (@CorwinWright) March 3, 2022 *** California is in a NWS Tsunami "Advisory" – — California Geological Survey (@CAGeoSurvey) January 15, 2022 #Tsunami potential #AmericanSamoa #VolcanicEruption https://t.co/6bL0wRlNmX pic.twitter.com/QqLXC79pQK — Jason "Jay" R. Patton (@patton_cascadia) January 15, 2022 #TsunamiReport for #TsunamiAdvisory for the west coast of the USA & #Canada #Alaska #BritishColumbia #Washington #Oregon #California see https://t.co/rEduVE2EDc for more updates and recommendations pic.twitter.com/gLkB833R22 — Jason "Jay" R. Patton (@patton_cascadia) January 15, 2022 #TsunamiAdvisory remains in effect for the #WestCoast, with peak tsunami wave heights of 1 to 3 feet possible. Main impacts expect to be strong rip currents and coastal flooding of some immediate coastal low-lying areas. #CAwx — NWS Eureka (@NWSEureka) January 15, 2022 #Tsunami expect to reach #SanFrancisco around 8:10 am this morning, which will correspond with #HighTide for #SanFrancisco at 9:09 am. Expect low lying inundation and minor flooding possible, especially for areas like #MarinHeadlands. #Cawx pic.twitter.com/PoR3WYZ13D — NWS Bay Area (@NWSBayArea) January 15, 2022 #Tsunami expect to reach #SanFrancisco around 8:10 am this morning, which will correspond with #HighTide for #SanFrancisco at 9:09 am. Expect low lying inundation and minor flooding possible, especially for areas like #MarinHeadlands. #Cawx pic.twitter.com/PoR3WYZ13D — NWS Bay Area (@NWSBayArea) January 15, 2022 #TsunamiAdvisory remains in effect for the #WestCoast, with peak tsunami wave heights of 1 to 2 feet possible. Main impacts expect to be strong rip currents, coastal flooding, and inundation of low lying areas is possible. Move to higher ground. #CAwx — NWS Bay Area (@NWSBayArea) January 15, 2022 A Tsunami Advisory has been issued for Humboldt Co. due to volcanic activity in the S. Pacific. A tsunami capable of producing strong currents that may be hazardous to swimmers, boats and coastal structures is expected beginning 7:30-8 a.m. Widespread inundation is not expected. — Humboldt Co OES (@HumCoOES) January 15, 2022 Wow. Evacuation orders for Berkeley and Albany west of hwy. pic.twitter.com/dRvaSkCLwa — Cian Dawson 🏳️🌈 (@cbdawson) January 15, 2022 #SF remains in a Tsunami Advisory Strong, dangerous currents WILL be present. Stay out of water and away from coastal areas. pic.twitter.com/nMYm0wxvPA — SAN FRANCISCO FIRE DEPARTMENT MEDIA (@SFFDPIO) January 15, 2022 We continue to monitor the #Tsunami closely. Please listen to local advisories — stay safe and off beaches that are under a warning. https://t.co/M1QdOhBleG — Gavin Newsom (@GavinNewsom) January 15, 2022 Great resource for the #Tongaeruption tsunami arrival times, amplitudes, and r/t tide gauge observations.https://t.co/XOESHxHSuX pic.twitter.com/StO7eQo4Dh — Peter de Menocal (@PdeMenocal) January 15, 2022 I did an interview about an hour ago summarizing what's going on for Washington coastal areas. #tsunami https://t.co/V3qFtCFTkH — Harold Tobin (@Harold_Tobin) January 15, 2022 #TsunamiReport for the #TongaVolcano #TongaTsunami observations of #Tsunami in the #Caribbean #Atlantic #GulfOfMexico no action required use https://t.co/rEduVE2EDc to see notifications and recommendations pic.twitter.com/OrhBzGOASY — Jason "Jay" R. Patton (@patton_cascadia) January 15, 2022 #TsunamiReport for #TongaTsunami #Tsunami advisories have all been cancelled for the west coast of the US & Hawai'i from https://t.co/rEduVE2EDc the [#mostimportant] first level Blooms Taxonomy for learning = #Discovery this event will not disappoint in this regard #StayTuned https://t.co/z8LpWAAOI7 pic.twitter.com/4zSgmpH9rX — Jason "Jay" R. Patton (@patton_cascadia) January 16, 2022 Update from Tongans on FB… clean up begins, #tsunami alert remains, masks advised. Stay safe, stay alert 🙏 #Tonga #tsunamitonga #TongaVolcano pic.twitter.com/GGxIw0Kw0u — Josephine Latu-Sanft (@JoLatuSanft) January 16, 2022 There has been another eruption from the volcano in Tonga. — National Weather Service WSO Pago Pago (@NWSPagoPago) January 16, 2022 Tonga Volcanic Eruption and Tsunami: World Bank Disaster Assessment Report Estimates Damages at US$90M https://t.co/bx6Iq5VTyb via @WorldBank — Jason "Jay" R. Patton (@patton_cascadia) March 7, 2022 ➡️https://t.co/ZDdvztAIKj https://t.co/oNuTw3G5s9 pic.twitter.com/LsA3PfAoJq — California Geological Survey (@CAGeoSurvey) January 17, 2022 A #Tsunami Advisory means: a dangerous wave is on the way. Strong and unusual currents are expected along the coast, and in bays, marinas, and harbors. Move to high ground and away from the shore. More at https://t.co/npoUHxEZLS. pic.twitter.com/MCLDdN9qPp — NWS Tsunami Alerts (@NWS_NTWC) January 15, 2022 #Tsunami INFO CA Tsunami Preparedness Guide website: https://t.co/UB3BAS55Pz — Nick Graehl (@nickgraehl) January 15, 2022 yes, don't forget to check out the #Tsunami Hazard Areas (where people might want to evacuate from during a tsunami event) for #California are available at https://t.co/9LPXadKWEi these are produced by the #CaliforniaTsunamiProgram a collaboration between @Cal_OES & @CAGeoSurvey pic.twitter.com/IaC13oef9b — Jason "Jay" R. Patton (@patton_cascadia) January 15, 2022 There are a number of #Tsunami HAZARDS that could directly impact harbors and boaters: continued… pic.twitter.com/1BRSOnjmYC — Nick Graehl (@nickgraehl) January 15, 2022 If you want to interact with all the tide gage data, here’s the NOAA interactive website that is pretty great!https://t.co/2SsAokmaB3 https://t.co/PMMLH35BJv pic.twitter.com/6nrXmekebL — Ryan Hollister (@phaneritic) January 15, 2022 Tsunami arrival + high tide = maximum wave run-ups pic.twitter.com/6mjQltYO45 — Brian Olson (@mrbrianolson) January 15, 2022 The #tsunami warning centers post all their messages to https://t.co/Em3fOFG82S. If you live on the US West Coast, Alaska, or British Columbia, make sure you check the messages for your region. pic.twitter.com/AJtJN9oZWg — Dr. Amy Williamson-Liuzzo (@AWilliamsonSci) January 15, 2022 If you're having a hard time interpreting news about this tsunami advisory — what the danger is and where — @DaveSnider breaks it down really well in this video on the warning center's facebook page.https://t.co/tHsstcS5xl — Ian Dickson (@IanJDickson) January 15, 2022 First signs of damage in the upper harbor. #santacruz. pic.twitter.com/p26hdpnSOn — Tim Cattera Photo (@TimCatteraPhoto) January 15, 2022 The Hunga Tonga-Hunga Ha'apai volcanic eruption was heard here in Alaska starting around 3:30 a.m. – 6,000 miles from the volcano! Infrasound measurements from the @alaska_avo confirm that it was indeed coincident with the volcanic pressure wave. Special thanks to Dr. David Fee. pic.twitter.com/Wp4tnwiaud — NWS Alaska Region (@NWSAlaska) January 15, 2022 2. Tsunamis are not one wave. It's more like sloshing and that sloshing can continue for a day. Just because the first wave has passed, it is not time to go see the beach. — Dr. Lucy Jones (@DrLucyJones) January 15, 2022 Don't be these people. Today is not the day for it. Stay off the coastal beaches and jetties. #wawx pic.twitter.com/4o0fhpJei8 — NWS Seattle (@NWSSeattle) January 15, 2022 Wondering why you didn't get an alert about the #Tonga tsunami and the #TsunamiAdvisory in WA this morning? There are many ways to get tsunami alerts and it's best to be signed up for many kinds! Learn more about tsunami alerts (and other hazard alerts) at https://t.co/iU0UZFRnC2 pic.twitter.com/aRkJ2CKB32 — Washington ShakeOut (@waShakeOut) January 15, 2022 After checking with @LoriDengler, I think that today is the first-ever Pacific-wide #tsunami alert from a volcanic eruption. Interestingly, the warning center needed an earthquake magnitude to issue the bulletin. So they made one up: mag 0.1! (Now changed to mag 1) pic.twitter.com/znjfUa1o3S — Harold Tobin (@Harold_Tobin) January 15, 2022 This was not your run of the mill way a #tsunami is generated. Most often its from plates shifting abruptly on the sea floor. This tsunami was essentially caused by a massive underwater explosion of molten rock and lava that displaced the water above it. pic.twitter.com/JyLwZYHcRp — NWS Los Angeles (@NWSLosAngeles) January 15, 2022 Not sure I have ever seen this before. My @noaaocean colleague just flagged this. The pressure wave caused by the #TongaVolcano is also actually causing a tsunami – in this case a meteotsunami of about 10cm in Puerto Rico. Wild. pic.twitter.com/EapEuNhjB5 — Greg Dusek (@DrGregDusek) January 15, 2022 A #volcano just erupted near #Tonga – but why was it there in the first place? Tonga sits on top of the #TongaKermadec #subductionzone, where the #PacificPlate sinks below the #AustralianPlate. The subducting #PacificPlate carries the culprit into the mantle: #water. 🧵1/3 https://t.co/Z1ORgcBK5l pic.twitter.com/XN5cUCT8Yg — Dr. Judith Hubbard (@JudithGeology) January 15, 2022 Fascinating part of the tsunami warning process today: This wasn't an earthquake, so the tsunami warnings were sent out with a default magnitude of 1. Shows that our whole system is set up for earthquake tsunamis. 1/2 pic.twitter.com/pwsBuicyyX — Jackie Caplan-Auerbach (@geophysichick) January 16, 2022 Be #prepared for tsunamis. — John Cassidy (@earthquakeguy) January 16, 2022 If you’re not already following all these great folks, then do yourself a favour and follow them. I’d also add to the list:@heatherkhandley @SquigglyVolcano @Volcanologist @VolcanoDoc@scarlett_jazmin@simoncarn https://t.co/RrfVVNGmQf — Mark Tingay (@CriticalStress_) January 17, 2022 Interactive Tsunami Flood Risk Map Asks: Are You in the Zone? https://t.co/WnvKidKNjE — Jason "Jay" R. Patton (@patton_cascadia) January 17, 2022 Great questions here about hydrophones as a tool to monitor submarine volcanism. This is my favorite topic, so @syabilazriAS is going to get a longer answer than maybe was desired. 😆🧵 https://t.co/VcbgmUEnZn — Jackie Caplan-Auerbach (@geophysichick) January 18, 2022 The highest concentration of sulfur dioxide (SO2) in the world right now is over the Pacific 📈 This is associated with the eruption of the Hunga-Tonga-Hunga-Ha'apai volcano 🌋 🧵 on what this means… pic.twitter.com/yjgT0yWdL8 — NIWA Weather (@NiwaWeather) January 17, 2022 For additional information on #TsunamiPrep check out "The TsunamiZone" @thetsunamizone and https://t.co/o336WXPPqj pic.twitter.com/dE1QT3QSPc — California Geological Survey (@CAGeoSurvey) January 17, 2022 High tide is around 9:30 AM along the Northwest California coast. Even though the initial wave is expected 7:30 AM to 8 AM, additional waves and strong currents will continue. As much as 3 feet of tsunami wave is expected. Stay back from the beaches and lowest-lying areas. #CAwx pic.twitter.com/BmoCVtJc2f — NWS Eureka (@NWSEureka) January 15, 2022 WATCH: Tsunami from Tonga volcano eruption starting to cause minor flooding in Santa Cruz, California pic.twitter.com/ELq8IKMEUV — BNO News (@BNONews) January 15, 2022 tsunami waves & high tide sloshing around west cliff. #MitchellsCove pic.twitter.com/yW2GLnFWzp — Dustin Mulvaney (@DustinMulvaney) January 15, 2022 Monterey Tide Station #Tsunami — Nick Graehl (@nickgraehl) January 15, 2022 #Tsunami observation update: — NWS Tsunami Alerts (@NWS_NTWC) January 15, 2022 Tsunami energy arriving at Del Monte Beach. Wave run up onto the beach is impressive. I'm safely distanced, but I saw other folks have to scramble when the waves unexpectedly reached them. Follow @NWSBayArea for #tsunami safety info. pic.twitter.com/JRl2XsTftI — Brooke Bingaman (@BrookeBingaman) January 15, 2022 Seeing some surges on the Port San Luis tsunami gauge. Reporting up to a 24 cm residual so far. That's 9.4 inches or about 19 inches from the bottom and top of the residual. More at https://t.co/SGd8WQoeji. #tsunami pic.twitter.com/bKYRRXuW4W — NWS Los Angeles (@NWSLosAngeles) January 15, 2022 Another huge surge in the back harbor. Bigger than the first one. #santacruz pic.twitter.com/gzzBmrq9dh — Tim Cattera Photo (@TimCatteraPhoto) January 15, 2022 Strong surge coming in now from #Tsunami in #RichmondCA at Meeker Slough mouth at the Bay. Highest level yet. Wild. pic.twitter.com/fevg14KZrX — Kenya Wheeler (@kenyaw) January 15, 2022 Made it to the high ground edge (6 feet+ above high water level) at Meeker Slough meets the SF Bay. Another observer tells me she has seen two surges already. Check the bridge piling for the high water mark from an earlier surge. pic.twitter.com/Vv8O00SLBF — Kenya Wheeler (@kenyaw) January 15, 2022 So far, business as usual at the Ferry Building, which sits above the expected tsunami surge. High tide in SF is at 9:25. It is probably just my imagination that the bay looks more unsettled this morning. pic.twitter.com/GkkSUSbBgY — Tim Dawson (@timblor) January 15, 2022 As usual, tsunami looks big in Crescent City, CA–waves still incoming. pic.twitter.com/iD0CSBV84O — Jackie Caplan-Auerbach (@geophysichick) January 15, 2022 Here is the current look at Half Moon Bay. You can see Pillar Point Harbor Patrol in the distance. #CaWx #California @sanmateoco @SMHarbor @NWSBayArea pic.twitter.com/z5HHnECtTE — CAL FIRE CZU (@CALFIRECZU) January 15, 2022 #TsunamiAdvisory for #SanFrancisco & #USWestCoast continues. @NWSBayArea reports #tsunami has already resulted in rapid swings up to 3 feet above/below forecast tidal level, or about 6 feet change in 30-60 minute intervals. https://t.co/PDR9BUlsMa #SFwx #CAwx #tongatsunami — Edie Schaffer, CEM (@sf_edie) January 15, 2022 10 AM | Here are the latest observed tsunami wave heights from along the West Coast of the US. Generally tsunami wave heights have been around 1 foot or less along the Oregon and Washington coast. (1/2) pic.twitter.com/r94If9ODXM — NWS Portland (@NWSPortland) January 15, 2022 Video from Cassidy Gillin of waves thrashing near the O’Neill lounge in Santa Cruz. Basic message for the day: don’t be brave. Stay away from the coast @KION546 pic.twitter.com/ieqK9nJ28A — Victor Guzman KION (@VGuzman_TV) January 15, 2022 From a friend at Santa Cruz Harbor @NWSBayArea @Weather_West pic.twitter.com/ZUgfXcbSxw — Dylan (@hamilton4391) January 15, 2022 The landing inundated here is 20 steps up. pic.twitter.com/zfU1XUoMhi — Dustin Mulvaney (@DustinMulvaney) January 15, 2022 This wave climbed up 15 steps higher to the next landing. #CAwx #TsunamiWarning pic.twitter.com/dyRPHjBArP — Dustin Mulvaney (@DustinMulvaney) January 15, 2022 Current look at Surfer’s Beach in El Granada #CaWx #California Stay on higher ground. @NWSBayArea @SMHarbor pic.twitter.com/MMwkMXXr8R — CAL FIRE CZU (@CALFIRECZU) January 15, 2022 The scene at the Santa Cruz Harbor as a tsunami generated tidal surge causing damage Saturday morning #TsunamiAdvisory pic.twitter.com/9ijKU9ZVaK — Vern Fisher (@VFisher45) January 15, 2022 Another surge and it’s now receding once again. Not as high as the first one. #santacruz pic.twitter.com/JIKfhxvZrM — Tim Cattera Photo (@TimCatteraPhoto) January 15, 2022 SURFERS EVACUATED | A surf competition was canceled and surfers were evacuated from the ocean in Santa Cruz due to the tsunami. https://t.co/8sAslNmUko pic.twitter.com/dmfKkEGzFE — KSBW Action News 8 (@ksbw) January 15, 2022 Here's the latest observed heights over tidal predictions along the West Coast pic.twitter.com/qj6pcrIS5r — NWS Eureka (@NWSEureka) January 15, 2022 The tsunami advisory remains in effect. High tide occurred through the morning, and total water levels are decreasing, lowering risk of coastal flooding, but rapid fluctuating surges of water onto and off of the coast/strong currents will continue thru the remainder of the day. pic.twitter.com/5ylsGGvr0m — NWS Bay Area (@NWSBayArea) January 15, 2022 #TSUNAMI water is literally draining out of #ventura harbor. @KTLAnewsdesk @KCBSKCALDesk @KEYTNC3 @vcstar @ABC7Desk @WeatherNation @805Weather @Weather_West @NWSLosAngeles pic.twitter.com/Tjccw1k613 — FireOFire (@FireOFire) January 15, 2022 Here are the latest maximum observed wave heights. Highlights for our area include 3.7 feet at both Crescent City and Arena Cove. The advisory continues for the West Coast, stay tuned to the latest updates on the advisory from @NWS_NTWC pic.twitter.com/UYwFWWLGWd — NWS Eureka (@NWSEureka) January 15, 2022 @Ocean_Networks #knowtheocean sensors tracked the Tonga tsunami wave as it travelled across 🇨🇦’s offshore lands. Data also provided to @NOAA tsunami alert system. pic.twitter.com/MMfjvUrM3b — Dr. Kate Moran (@katemoran) January 15, 2022 Soquel Creek in Santa Cruz flowing *backwards* because of a tsunami 🤯 pic.twitter.com/JxFsllhhdX — robwormald (@robwormald) January 15, 2022 This is from up Soquel Creek pic.twitter.com/ySRF6Okh8o — Kristen (@KRice7) January 15, 2022 #ventura #TsunamiAdvisory #tsunamitonga pic.twitter.com/JqTOqZk9Yf — MJ (@mbearwoman) January 15, 2022
#TsunamiReport for #Tonga #Tsunami recorded on @NOAA tide gages in #California #TongaTsunami #TongaEruption pic.twitter.com/wV6FThMELO — Jason "Jay" R. Patton (@patton_cascadia) January 19, 2022 Tsunami surge up the mouth of San Luis Creek at Avila Beach (Port San Luis) #tsunami — Brian Olson (@mrbrianolson) January 21, 2022 Santa Cruz Harbor back on solid footing post-tsunami, but long-term repairs loom https://t.co/uh5iiPMA8j <– Max Chun with the update on @SantaCruzHarbor after Saturday's #tsunami pic.twitter.com/8kryBrCfc5 — Lookout Santa Cruz (@LookoutSCruz) January 21, 2022 Neskowin, Oregon this morning! #tsunamitonga #TSUNAMI pic.twitter.com/YQJjaFL5w1 — retelling•the•recipe (@tiggirltk) January 15, 2022 #tsunami in #DepoeBay pic.twitter.com/aknFfQkRnk — jim (@jimfromoregon) January 15, 2022 1145 AM Update | The largest waves have spared much of the Oregon Coast so far. Tsunami wave observations so far include… 24 cm (.8 ft) at Charleston, OR (1/2) — NWS Portland (@NWSPortland) January 15, 2022 Unexpected #Tsunami #HungaTongaHungaHaapai #Tsunami #Tonga #Earthquake pic.twitter.com/p16v9c0zLt — Journalist Siraj Noorani (@sirajnoorani) January 15, 2022 Stay safe everyone 🇹🇴 pic.twitter.com/OhrrxJmXAW — Dr Faka’iloatonga Taumoefolau (@sakakimoana) January 15, 2022 The #HungaTongaHungaHaapai eruption is showing up in the tide gauge records at Suva, Apia, Rarotonga and Funafuti. Below is the real time data for the Suva tide gauge. https://t.co/2qBzfVsSJz pic.twitter.com/DXeccmsNw2 — Murray Ford (@mfordNZ) January 15, 2022 Tide gage in American Samoa registering the tsunami created by the Tonga submarine volcanic eruption. Peak amplitude so far is 0.74 meter (~2.5 feet). pic.twitter.com/ATsmnP5clg — Brian Olson (@mrbrianolson) January 15, 2022 ~ 2 Meter #Tsunami in Nuku'alofa, Tonga nach der erneuten heftigen Explosion des Hunga Tonga-Hunga Ha'apai Vulkans. Die ersten Wellen haben auch Fidschi erreicht. Ich hoffe, die seit gestern bestehende Tsunami-Warnung wurde ernst genommen https://t.co/akfdQqtrP7 pic.twitter.com/b90hbS4oTW — Jens Skapski (@JensSkapski) January 15, 2022 For any New Zealand tsunami updates during the Tonga Hunga Tonga-Hunga Ha'apai eruption go here: https://t.co/y020MigfFn — Dr Janine Krippner (@janinekrippner) January 15, 2022 Here are @BOM_au’s latest observations on the waves #Tonga #tsunami 👇 While a 1m wave might not sound big, tsunami have much longer periods (the time between each wave) than wind waves so even a 1m wave can cause significant damage and flooding! pic.twitter.com/27DoahlJEb — A/Prof Hannah Power (@DrHannahPower) January 15, 2022 And same @BOM_au #Tonga #tsunami data again for #NorfolkIsland. Lots of waves and some very big ones! Worth remembering that a #tsunami is more often a series of waves lasting several hours and not just one wave. https://t.co/YH44vAozIG pic.twitter.com/qNmvPc8akD — A/Prof Hannah Power (@DrHannahPower) January 15, 2022 #TsunamiReport for observations of #Tsunami from Tonga volcanic eruption in #CrescentCity #California for recommendations and updates head to https://t.co/rEduVE2EDc for more information the entire west coast of the USA is under a tsunami advisory pic.twitter.com/PJBwLsS7jN — Jason "Jay" R. Patton (@patton_cascadia) January 15, 2022 The plot shows water level data from Honolulu, Hawaii. It indicates that the tsunami continues to impact the Hawaiian islands at least 7 hours after initial arrival. Expect a similar, long duration event along our coast and bays today. pic.twitter.com/LfaS7O8u3A — NWS Bay Area (@NWSBayArea) January 15, 2022 El Servicio Mareográfico del Instituto de Geofisica de la UNAM, muestra que el puerto de #Manzanillo, #Colima muestra el arribo de las olas del #tsunami. pic.twitter.com/nYPJRck9N2 — Alejandro S. Méndez ⚒️ (@asalmendez) January 15, 2022 Muy buena foto !! Interesante comparar los efectos con lo que observa el mareógrafo. Este indica 40 a 60cm de desviación respecto de valores medios. El tsunami sigue en desarrollo. Gracias !! pic.twitter.com/f4WzPs2sMn — Luis Donoso (@Geo_Risk) January 15, 2022 16日午前0時半前、津波注意報が出されている高知県土佐清水市の港の映像からは、海面が上下するのにあわせて係留されている船がゆっくりと上下したり左右に揺れたりしている様子が確認できます。https://t.co/5plmIcphz6#nhk_video pic.twitter.com/2spq3znm6c — NHKニュース (@nhk_news) January 15, 2022 WATCH: Tsunami from Tonga's volcano eruption causes flooding in northern Chile pic.twitter.com/SQ8wtnM06i — BNO News (@BNONews) January 15, 2022 Small but powerful #tsunami surges reached Currarong Creek on NSW south coast between 7-8am this morning pic.twitter.com/7BteF0fhg2 — Casey Kirchhoff (@gumnut_case) January 15, 2022 😲 this video is pretty crazy.. shows the #Tsunami pushing the water up canals in #Chile 🇨🇱 Shows the power of the ocean.. 🎥 @SouthPatriotCL #Tonga #Chili #HungaTonga #HungaTongaHungaHaapai #MotherNature #TsunamiWarning #SouthAmerica pic.twitter.com/FUBzMRws12 — Bryce Campbell🤷🏻♂️ (@BCampbell_24) January 15, 2022 🌊 #Tsunami …sea is receding at Playa de Los Molles in the Valparaíso region of #Chile 🇨🇱 in South America 🤯 🎥 @AgenciaQuinta #HungaTongaHungaHaapai #MotherNature #TsunamiWarning #NationalTsunamiWarning #Earthquake #TsunamiAdvisory #SouthAmerica pic.twitter.com/4X0PVMZLtD — Bryce Campbell🤷🏻♂️ (@BCampbell_24) January 15, 2022 Footage from Niue… crazy sea activity at Sir Robert’s Wharf, Alofi Bay following the #HungaTonga volcanic eruption.. 🌊 🇹🇴#Volcano #Tonga #HungaTonga #HungaTongaHungaHaapai #underwater #Tsunami #Oceania #MotherNature pic.twitter.com/Qptj4yf36q — Bryce Campbell🤷🏻♂️ (@BCampbell_24) January 15, 2022 Timelapse video of the #tsunami taken at Mogareeka inlet at 7-7:20am this morning. Tide is rising (flow left to right) but here is what happens as the waves come through. Mogareeka is usually very flat so the effects are amplified @anuearthscience @ourANU pic.twitter.com/y00Tj1iFb3 — Louis Moresi (@LouisMoresi) January 15, 2022 Urgente Marejadas destruyeron otro muelle en Las Coloradas sector Isla del Rey comuna de Corral, los ríos. — (@EarthquakeChil1) January 15, 2022 A #tsunami is occurring. Tsunami Advisories have been ended for portions of Southcentral and Southeast Alaska- they continue elsewhere. See https://t.co/npoUHxWBas for the latest. — NWS Tsunami Alerts (@NWS_NTWC) January 15, 2022 Some first pics coming out of #Tonga post #Tsunami #volcanoEruption This is in the outer islands Pangai, Haapai. Roads ripped up. Seems some of those massive chunks are pieces of the seawall. #tongatsunami #TongaVolcanoEruption — Josephine Latu-Sanft (@JoLatuSanft) January 16, 2022 https://t.co/Xw7BUtepv4 article with early news about what is happening inside Tonga. Communications are difficult. Tonga volcano: Photos and video give first glimpse of tsunami's impact https://t.co/j5LDZ3B6lP — Dr. Eric J Fielding, PhD (@EricFielding) January 16, 2022 We knew there would be tragedy associated with this event, but seeing it is dreadful. My thoughts are with the Tongan people. https://t.co/eFSbDYRzWE — Jackie Caplan-Auerbach (@geophysichick) January 17, 2022 1Hz microbarograph data from the @geoscope_ipgp seismographic station at Tamanrasset, Algeria https://t.co/2UcaNmFzvShttps://t.co/8PeWmn2OxL pic.twitter.com/tVyMeCnWZV — Anthony Lomax 😷💉🇪🇺🌍 (@ALomaxNet) January 17, 2022 Eruption update: Parts of the Hunga Tonga-Hunga Ha'apai conjoined island that sat atop the largely underwater volcano could be seen via satellite. In December, the eruption caused it to expand in size. Just prior to the blast, it shrank again. Today? It's all but vanished. https://t.co/k5IjZLq5cE — Dr Robin George Andrews 🌋 (@SquigglyVolcano) January 17, 2022 1/n Lot of damages and very complicated aftermath in Tonga islands. — Robin Lacassin (@RLacassin) January 18, 2022 Offical announcement from the Government of Tonga. Tragically, 3 people confirmed to have died. Also, while there are many satellite images coming out showing the awful eruption impact, please be compassionate and considerate to those impacted or awaiting news of loved ones. https://t.co/Vw2SfHEHjh — Mark Tingay (@CriticalStress_) January 18, 2022 Here is a map depicting damage in the islands of #Tonga from the huge eruption of Hunga Tonga-Hunga Ha’apei #volcano, derived from #sentinel1 #sar data. Our hearts are with the people of Tonga. More information and kml at https://t.co/uxKeZHJ0ix pic.twitter.com/shEl0xOV33 — EOS Remote Sensing (@eos_rs) January 18, 2022 .@patton_cascadia @VolcanoSimon 🤔 Can @CopernicusEU #Sentinel1 wave field and timing tell us any thing about what may have happened underwater around Hunga Tonga ? https://t.co/8yNbj5Lk0x — DPManchee (@DPManchee) January 19, 2022 Three days after the disastrous eruption of the #HungaTonga #volcano, #Tonga is still isolated@CopernicusEMS has been activated ⬇️The effects of the explosion on Nomuka Island are visible when comparing the #Sentinel2 🇪🇺🛰️images of — 🇪🇺 DG DEFIS #StrongerTogether (@defis_eu) January 18, 2022 Distance was no barrier to providing critical real-time #tsunami data following Saturday's #TongaEruption. 9000km from this rare underwater #volcano event, our #UVic #knowtheocean sensors informed @NWS_PTWC alerts and will inform future research. Read: https://t.co/FPECte9dP1 pic.twitter.com/DJX6z2pUPp — Ocean Networks 🇨🇦 (@Ocean_Networks) January 19, 2022 🇹🇴The miracle survival of a 57-year-old disabled man who survived in the ocean for 27 hours after being swept away by a tsunami wave is one of the first astonishing accounts to emerge from Tonga Thread🧵👇https://t.co/m5uaVTFnoT pic.twitter.com/87n3TUs0T0 — Telegraph World News (@TelegraphWorld) January 20, 2022 This map, based on #alos2 #sar satellite data, shows the devastating impact of the huge #Tonga volcanic eruption. Damaged areas are marked by yellow to red pixels, with red indicating the most damage. More info, GeoTIFF and KMZ files at https://t.co/uxKeZHJ0ix pic.twitter.com/2xSSZeYVbH — EOS Remote Sensing (@eos_rs) January 23, 2022 — Ailsa Naismith (@AilsaNaismith) February 1, 2022 Quite the day at the beach sampling the January 2022 Hunga tsunami deposits- if you squint there are ?3 slightly different grainsize layers here – plus thin black layer of ash near the top, western Tongatapu pic.twitter.com/oZcEPGxeO6 — Shane Cronin (@scronin70) April 6, 2022 Extracting oriented tubes of tsunami deposits will help colleagues figure out deposition histories using 3D magnetic and textural properties- Hunga tsunami deposits – western Tongatapu pic.twitter.com/ojcoi9kiSP — Shane Cronin (@scronin70) April 6, 2022 Tonga tsunami, quite impressive that it propagated all the way to stations in the coast of Mexico (Manzanillo over 1.4m) and California… Here is a order one attempt to model this tsunami @geosmx #geoclaw pic.twitter.com/drzz5GMHJK — angel ruiz (@angelruizangulo) January 15, 2022 Ash plume extent update for Hunga Tonga-Hunga Ha'apai eruption in Tonga. — Dr Janine Krippner (@janinekrippner) January 15, 2022 Truly incredible imagery from the Himawari meso sector of multiple shockwaves from a volcanic eruption on Tonga propagating through what was recently subtropical storm Cody. My back of the napkin math estimates put the shockwave speed somewhere in the vicinity of 500-600 mph. pic.twitter.com/lDyNXFpLbE — Isaac Schluesche (@SlushyWx) January 15, 2022 Find the eruption. 🌋 pic.twitter.com/0xUWE8spzh — Brian Brettschneider (@Climatologist49) January 15, 2022 Tonga's Hunga Tonga volcano just had one of the most violent volcano eruptions ever captured on satellite. pic.twitter.com/M2D2j52gNn — US StormWatch (@US_Stormwatch) January 15, 2022 This volcano eruption is producing some sights we won't see on satellite for a while after. The explosive updraft powers right into the stratosphere, and the warming with height there makes the blob appear warm/shallow. There's also the shockwave and condensation pushing NE pic.twitter.com/6ud79uws9w — Alex Boreham (@cyclonicwx) January 15, 2022 1.14.2021: Large volcanic eruption near Tonga (Hunga Tonga-Hunga Ha'apai volcano) today as seen from outer space. Shown on visible imagery using the Himawari satellite. #hiwx #tsunami #earthquake pic.twitter.com/zOTj6Qu1Wv — NWSHonolulu (@NWSHonolulu) January 15, 2022 Shock wave from the big eruption of Hunga-Tonga-Hunga-Ha'apai today seen on @raspishake infrasound station in Auckland. Time on bottom is UTC+8 – add 5 hours to get local time in New Zealand. pic.twitter.com/e6Ns7gLGS7 — Mark Tingay (@CriticalStress_) January 15, 2022 Fantastic #infrasound signals on the Australian IMS arrays from the #Tonga #volcano. Data courtesy of @GeoscienceAus and made available via @IRIS_EPO – these atmospheric waves travel much slower than seismic waves and over an hour separates the signals on mainland Australia. pic.twitter.com/7A8KUZdA22 — Dr. Steven J. Gibbons (@stevenjgibbons) January 15, 2022 The pressure wave from the Hunga Tonga-Hunga Ha'apai eruption arrived here in Anchorage at 3:30 a.m. AKST. This is exactly 7 hours after the eruption. The volcano is 5,820 miles away (9,360 km). That means it travelled at 830 mph (1,340 kmh). pic.twitter.com/R3rgzAbo6r — Brian Brettschneider (@Climatologist49) January 15, 2022 Seismogram from Monasavu, Fiji ~800km NW of Hunga Tonga-Hunga Ha'apai eruption. Assuming main eruption at ~04h15mUTC, shows P waves, seismic surface waves (Lq, Lr) and oceanic SOFAR acoustic waves (T). Signal from the eruption continues for 2+ hours.https://t.co/etU65z1wyq pic.twitter.com/2PublssOYm — Anthony Lomax 😷💉🇪🇺🌍 (@ALomaxNet) January 15, 2022 A number of folks have posted similar obs, but here are two pressure traces showing the #HungaTongaHungaHaapai shock wave observed at UNR in Reno and UoU in Salt Lake City this morning. The SLC data seem to show subsequent oscillations (sloshing) in the valley cold pool. #UTwx pic.twitter.com/ekDRXUUrq8 — Neil Lareau (@nplareau) January 15, 2022 A similar pressure bump was observed in Portland, Oregon early this morning as well. See the right hand column in the attached 5 minute data from the Portland Airport. #ThePowerOfTheVolcanoEruption #pdxtst #orwx #wawx https://t.co/ITFTtfbEwM pic.twitter.com/T2dXs2zqf5 — NWS Portland (@NWSPortland) January 15, 2022 Here's the latest eruption. Again ice detectable. This time ash signal appearing. Plume appears to be significantly stronger than the last one. I've set the colour bar and scale to try to highlight the tropospheric and stratospheric portions of the plume (top left plot). pic.twitter.com/zRaFvG2jvJ — Andy Prata (@andyprata) January 15, 2022 6 hours of infrared satellite in 4 seconds. You can see the atmospheric shock wave ripple out Pacific-wide after the initial #eruption in #Tonga (quite hard to see but it crosses #Hawaii and #Australia). People as far away as Southland in #NewZealand reported hearing the booms. pic.twitter.com/a0YHx4Q0q0 — WeatherWatch.co.nz (@WeatherWatchNZ) January 15, 2022 A @planet SkySat image appears to have been acquired ~2 hours *before* the 04:00 UTC 15 Jan 2022 #HungaTongaHungaHaapai. The whole central part of the island was missing, probably blown up in the 14 Jan 2022 explosions. @janinekrippner @SmithsonianGVP @rsimmon pic.twitter.com/5Vtuu1fOvV — Raphael Grandin (@RaphaelGrandin) January 15, 2022 #Tonga 🇹🇴🌋 Antes y después #HungaTongaHungaHaapai Una reciente imagen tomada por los satélites de #SkySat propiedad de Planet Labs. muestra que el corredor de tierra que existía desde 2014 entre las islas desapareció después de las erupciones cataclísmicas de ayer. pic.twitter.com/2fM8rwNPZS — Alejandro S. Méndez ⚒️ (@asalmendez) January 15, 2022 That map, created with April 2016 data from the R/V Falkor, showed details of the overall volcanic edifice. Measured on this quick Google Earth overlay, the diameter of the caldera rim is ~6 km. Recent eruptions have been on the N and NE sides. Red * is 2009 vent. pic.twitter.com/oPdKMR44G3 — Global Volcanism Program (@SmithsonianGVP) January 15, 2022 We now have some one-minute infrared imagery of the ongoing eruption, via GOES-17. pic.twitter.com/ZxdhVqxWqU — Dakota Smith (@weatherdak) January 15, 2022 Jumping on board pressure perturbation Twitter to share this animation of @okmesonet pressure data. Several pressure waves created by the Hunga Tonga–Hunga Ha'apai volcano eruption in Tonga passed from southwest to northeast across Oklahoma between 7 and 9 AM CST this morning. pic.twitter.com/aBpRXNbNeX — Tim Supinie (@plustssn) January 15, 2022 Shockwave from the #HungaTongaHungaHaʻapai eruption visible as an abrupt pressure change across the @UVicSEOS Climate Network at about 4 a.m. this morning https://t.co/J6FhLuG6C6 @edwiebe @AJWVictoriaBC @UVicScience pic.twitter.com/LIowFgAssj — Dr. Edwin Nissen (@faulty_data) January 15, 2022 A Planet SkySat captured an image of Hunga-Tonga Hunga-Ha’apai today at 2:25 UTC, just two hours before its violent eruption that triggered a tsunami. Read @tanyaofmars' latest blog for more details on our monitoring of the volcano: https://t.co/8MdAAnopeK pic.twitter.com/RG68ADVSEV — Planet (@planet) January 15, 2022 Tonga tsunami is arriving at BC! Last twelve hours of seafloor pressure data show: Series of waves, starting to arrive at @Ocean_Networks stations at 8:22 PST, and at the west coast about 9 AM PST. Height about 5 cm offshore. Coastal currents probably a bigger issue. #BCTsunami pic.twitter.com/VpEzXymHB3 — Martin Scherwath (@mscherwath) January 15, 2022 1-min CG lightning plot of #Tonga eruption pic.twitter.com/Dt0exOhvG7 — William Churchill (@ChurchillWx) January 15, 2022 Tonga Volcano eruption heard from Lakeba, Fiji 😢🇹🇴 #TongaVolcano pic.twitter.com/qc9ISL25QX — Portia Dugu (@portiajessene) January 15, 2022 Ionospheric total electron content (TEC) perturbations derived from a GNSS site on Samoa from the Hunga Tonga eruption were not small to say the least @IGSorg pic.twitter.com/bMa8MKCZ3o — Brendan Crowell (@bwcphd) January 15, 2022 Huge volcanic eruption near Tonga. Reports of tsunami there and it's gone pitch black. Lots of lightning too. #tonga pic.twitter.com/Eia4fidPRc — Rick Threlfall (@RickThrelfall) January 15, 2022 Putting the #Tonga #eruption into perspective. It's an astonishing event. Link to story/infographics here: https://t.co/HLIzcRI8eMhttps://t.co/Pm2OWgcGPf pic.twitter.com/oUrc71jcJf — WeatherWatch.co.nz (@WeatherWatchNZ) January 15, 2022 15 minute pressure altimeter change via ASOS NWS/MADIS 5 minute interval data. Shows the shockwave from the #Tongaeruption , feel free to use as you wish. pic.twitter.com/P31Aq1SYku — daryl herzmann (@akrherz) January 15, 2022 Longwave infrared channel via #GOESWest of the #Tonga eruption.. one of the most incredible satellite animations I've ever seen. The relative warmth of the ash cloud atop the very cold tropospheric convective anvil. Waves upon waves. Simply incredible. pic.twitter.com/MoBcIxkblW — William Churchill (@ChurchillWx) January 15, 2022 New data alert 🚨 We just overflew Hunga Tonga-Hunga Ha'apai volcano with #Sentinel1 🛰️🌋 The datatake didn't include #Tonga main island, where I desperately hope everyone is safe 🇹🇴❤️🩹Here's our last 3 passes over the volcano… pic.twitter.com/KD39030U5S — Thomas Ormston (@ThomasOrmston) January 15, 2022 <トンガの火山噴火の衝撃波か> — ウェザーニュース (@wni_jp) January 15, 2022 The evolution of the volcanic island of Hunga Tonga over time, with the last image having been taken just two hours before the massive eruption last night. Curious to see the scene after that… Images from Google Earth and @planet. pic.twitter.com/lOmca4Du7I — Alex Spahn (@spahn711) January 15, 2022 This is the most incredible #lightning loop that I have ever put together. #HongaTongaHungaHaapai #HungaTonga #Volcano eruption today with nearly 400k lightning events in just a few hours! pic.twitter.com/xqW70NLeVd — Chris Vagasky (@COweatherman) January 15, 2022 Looks to me like we see the seismic signal from the Tonga eruption at Weston, MA and Westport, CT. — Alan Kafka (@Weston_Quakes) January 15, 2022 Is it possible that we see pressure changes in Slovakia too? Graphs time UTC+1. pic.twitter.com/jD0gy3iflc — Blažej Krajňák (@BlazejKrajnak) January 15, 2022 Before and after photos show that the island of Hunga Tonga and Hunga Ha'apai is essentially gone following the explosive eruption of the volcano last night. https://t.co/6GvI5nNGV2 pic.twitter.com/wEjBhfmWFZ — Kaylan Patel (@WxPatel) January 15, 2022 If this estimation is correct, this is huge!!! https://t.co/7VKIsj5ovQ pic.twitter.com/NM5qeqeccB — Sarah Lambart (@Sarah_Lambart) January 15, 2022 A lot of talk about just how big the eruption at Hunga Tonga-Hunga Ha'apai was. It might be awhile before we know & we don't know if there is more to come. Questions abound about what caused the tsunami, why the eruption was so explosive, etc https://t.co/oXas1XevjC @DiscoverMag — Dr. Erik Klemetti Gonzalez (@eruptionsblog) January 15, 2022 With latest satellite imagery, we get a step closer to understand what happen with Hunga #Tonga leading to this ocean-wide #tsunami. Latest @sentinel_hub imagery shows the loss of a majority of the volcano's emerged landmass. However, most of its structure lies underwater. pic.twitter.com/odz5VcNphl — Andreas Schäfer (@DrAndreasS) January 15, 2022 The first #stratospheric #volcanic #eruption of 2022, at #HungaTongaHungaHaapai (#Tonga) on Jan 13-14. #Sentinel5P #TROPOMI & @NASA's Aura/OMI both measure ~0.05 Tg SO₂ in the #volcanic cloud – not enough for #climate impacts. @CopernicusEU @NASAEarth @volcanessa @MetService pic.twitter.com/f9tx76Z4Ow — Prof. Simon Carn (@simoncarn) January 15, 2022 Here’s a seismic record section of the Tonga volcanic eruption that’s causing the tsunami in the Pacific basin (h/t NEIC) pic.twitter.com/sljldhPFmh — Bill Barnhart (@SeismoSARus) January 15, 2022 Atmospheric wave response to Tonga eruption, from 4 UTC to 10:50 UTC. Slightly smoothed 10-minute change in GOES-17 band 13 (IR). Looks like some modest filtering would pull out a really clear signal. pic.twitter.com/CHZY7iv4HH — Dr. Mathew Barlow (@MathewABarlow) January 16, 2022 There are a lot of questions about VEI (Volcano Explosivity Index). I recognize that the want to compare this eruption is there, but there is so much information that we simply do not have. — Dr Janine Krippner (@janinekrippner) January 16, 2022 Pressure wave #2 passed here last night at about 11 p.m. This is the wave travelling from the opposite direction. Still had an impressive magnitude. pic.twitter.com/1fG4aKhWqs — Brian Brettschneider (@Climatologist49) January 16, 2022 Trying to understand why the weather stations at Stornaway on the Outer Hebrides measured the blast before us. Basically because the blast came from the north. Unbelievably the shortest distance between here and the South Pacific is over the North Pole. 🤯 #TongaVolcanoEruption pic.twitter.com/6MdZVJ4VWI — Dr David Boyce (@DrDavidBoyce) January 15, 2022 GNSS recordings (cm) at the IGS station TONG on the Tonga island by PRIDE PPP-AR (https://t.co/JOTbaSVeRq) during the Hunga Tonga volcano eruption on Jan 15, 2022. pic.twitter.com/tkNJd2mceC — Jianghui Geng (@GengJianghui) January 16, 2022 It appears that there is some minor activity ongoing at Hunga Tonga-Hunga Ha'apai, as expected. This is based purely on satellite data. No volcanic lightning detected.https://t.co/13uhR0353u — Dr Janine Krippner (@janinekrippner) January 17, 2022 Why does it take awhile to get satellite images of what's going on in #Tonga? We have to wait for satellites to fly over, or redirect them. Also, they "see" in different wavelengths, so night, clouds, and ash can obscure the view. But we should have updates soon! https://t.co/hWpCN8fe4R — Dr. Judith Hubbard (@JudithGeology) January 17, 2022 In Germany two main air pressure waves from the #Tonga eruption could be detection: The first wave traveled from north to south, while the second wave moved from south to north. The reason might be explained by the animation below, where I visualized an outgoing circular wave… pic.twitter.com/B57uRyy3ik — StefFun (@StefFun) January 16, 2022 A news story about Tonga. Most of the news in the U.S. is very American-centric, so you have to poke around the int’l news scene to get any news about Tonga.https://t.co/GXZlAIlsrQ — Pete R. Girguis (@pgirguis) January 16, 2022 Displacements measured at GPS/GNSS station TONG in Tonga about 70 km from #HungaTongaHungaHaapai shows large motion over about 10 minutes that returns close to previous position. Some kind of shock wave or seismic wave, probably. https://t.co/7Bpq2U8GsN — Dr. Eric J Fielding, PhD (@EricFielding) January 16, 2022 Copernicus Sentinel-1A radar imaged #HungaTongaHungaHaapai on 15 January 2022 after major eruption. Most of two islands and entire new cone was blown away, along with reef south of underwater caldera. @googleearth Engine HV radar polarization animation Aug-Jan by @TheHandwerger pic.twitter.com/gwnA52Q12e — Dr. Eric J Fielding, PhD (@EricFielding) January 17, 2022 So the Hunga Tonga and Hunga Ha'apai were two separate islands before an eruption in 2014-15, and they split up before the violent eruption last Saturday. And now, very little of the two islands are left. pic.twitter.com/5G7Zy3n0td — Annie Lau (@AYAnnieLau) January 17, 2022 SNPP/OMPS limb-profiler (OMPS-LP) aerosol vertical profiles from Jan 16 shown below captured the stratospheric #volcanic aerosol cloud reaching altitudes up to ~30 km (in same location as the highest SO₂ columns). h/t @NASAGoddard Ozone & Air Quality teamhttps://t.co/PBUPJCgEtJ pic.twitter.com/3eNIwouCfs — Prof. Simon Carn (@simoncarn) January 17, 2022 Don't know if anyone has plottet something similar already. — Felix Eckel (@FelixEckel) January 16, 2022 A THIRD pressure anomaly associated with the #TongaVolcano passed through #Miami on Sunday evening… the timing means that it was the first wave making a full trip around the globe! Absolutely mind-blowing power. pic.twitter.com/lpW9FY97Mw — Brian McNoldy (@BMcNoldy) January 17, 2022 Sure looks like we got a fourth passage of the Hunga Tonga – Hunga Ha'apai eruption shockwave in Utah. Timing is spot-on and signal is similar to previous passages. Interesting for sure but worried for the people of Tonga. pic.twitter.com/ZzZzTrIJcH — Michael Bunds (@cataclasite) January 17, 2022 Revisiting the Tonga volcanic shockwave: Here's the latest Eureka barograph showing the 1st shockwave, another distinctive shockwave just after midnight Sat night (the other side of the initial shockwave), & another possible shockwave just after noon today. #CAwx #Tongaeruption pic.twitter.com/c4bXjPcZrY — NWS Eureka (@NWSEureka) January 18, 2022 I’ve tried to annotate this here to help folks understand what it shows. pic.twitter.com/lCtuc4svaS — Mark Tingay (@CriticalStress_) January 18, 2022 The @EOS_SG blog post on the Hunga Tonga-Hunga Ha'apai eruption is up! Featuring the infrasound signal from the eruption as recorded in Singapore https://t.co/YMD56WZpqY — Anna Perttu (@InfraSaurus) January 18, 2022 I took a quick dive into the science of the volcanic eruption in Tonga. It was an extraordinary event that will keep researchers busy for a while… #TongaVolcano https://t.co/K0K3aQUv3s — Henry Fountain (@henryfountain) January 19, 2022 #HungaTonga #HungaTongaHungaHaapai #volcano #eruption effect on the #atmosphere thermal structure — Riccardo Biondi (@Richi_Biondi) January 19, 2022 Pressure waves from #HungaTongaHungaHaapai have travelled 3 times around the globe as of this morning. This pressure graph is from Iceland. It shows 6 peaks rather than just 3 because.. 1/n pic.twitter.com/W4WMOYswSV — Dr. Evgenia Ilyinskaya (@EIlyinskaya) January 19, 2022 Can we use the infrasound recordings of the #HungaTongaHungaHaapai eruption to estimate origin time and average sound velocity? Let's try with a semblance approach of the first arrival. Traces are time corrected for distance and velocity and stacked. pic.twitter.com/vjiqFLvmNm — Felix Eckel (@FelixEckel) January 20, 2022 Garvin et al. (2018) Fig.3 https://t.co/2MPkw4AGRe にある海底地形図をSentinel-2の衛星写真にジオリファレンスしてみた。黄色塗りつぶし箇所: 噴火後の島(17-Jan.) 黄色点線箇所: 噴火前の島(2-Jan.) pic.twitter.com/xcUtnVPJYv — F. IKGM🌏地球科学ニュース速報モード (@geoign) January 20, 2022 .@CopernicusEU @patton_cascadia @BBCAmos @Ifremer_fr @remi_wnd Wooooh ! Looks like #Sentinel1 Wave Mode products also caught the tsunami waves 🧐 – these from @Ifremer_fr XWaves The power of earth observation. pic.twitter.com/Dz3MCfFvmf — DPManchee (@DPManchee) January 20, 2022 Almost everything about Tonga's recent volcanic eruption has left scientists scratching their heads, from the sonic boom to the baffling tsunami. And it all happened from about an hour of volcanic fury. I dig into the many mysteries @NatGeohttps://t.co/y14NIIzEtk — Maya Wei-Haas, Ph.D. (@WeiPoints) January 20, 2022 (1/4) #CTBTO continues to analyze data from the Hunga Tonga-Hunga Ha'apai volcanic eruption. In terms of infrasound technology only, this is the largest event ever recorded by the #IMS infrasound network; much larger than the Chelyabinsk meteor in 2013. pic.twitter.com/T7y9Nk9Rhm — CTBTO (@CTBTO) January 21, 2022 #Copernicus for #volcano monitoring The eruption of the #HungaTonga volcano has released large amounts of SO2 into the atmosphere #Sentinel5P 🇪🇺🛰️captured the journey of the SO2 plume over Australia and the Indian Ocean ⬇️ Data from 15 January (before the 🌋) to 20 January pic.twitter.com/gDGUnilrvh — Copernicus EU (@CopernicusEU) January 22, 2022 衝撃波による津波,meteotsunamiというようです.今回のトンガの噴火はわからないことだらけです.長い記事ですが興味深いです.https://t.co/eye6fhiq3k — 遠田晋次 (Shinji Toda) (@EeWkKI8KqQLHUqz) January 22, 2022 Hunga Tonga, les travaux des communautés du pôle Terre solide de @dataterra #TongaVolcanoDataTerra: évolution de la morphologie de l'île volcanique avant et après l'explosion du 15/01 vue par satellite. Destruction de 90 % de l'île. https://t.co/kJhqZjVRtO pic.twitter.com/VM48FaQuMI — ForM@Ter (@ForMaTerre) January 25, 2022 The low-frequency signal from the Hunga Tonga-Hunga Ha'apai vulcanic eruption that generated the tsunami (15/01) was well captured by >400 #BMKG broadband seismic stations over the Indonesia region. The vertical record from five selected stations (bandpass filtered 0.01-0.05 Hz): pic.twitter.com/k2D3M6zClL — Dimas Sianipar (@SianiparDimas) January 27, 2022 Island nation of #Tonga is completely offline following a #tsunami triggered by a massive volcanic eruption in the Pacific Ocean. According to @kentikinc data, traffic volumes began to drop around 4:30 UTC (5:30pm local) before finally going to zero at 5:40 UTC (6:40pm local). pic.twitter.com/g4QZilBrd5 — Doug Madory (@DougMadory) January 15, 2022 Tonga shock wave converges and rebounds from antipodal point in North Africa. Faster than other animation because the wave front is harder to see. EUMETSAT IR data, 18 UTC 15 Jan – 2 UTC 16 Jan, 15-minute differences. pic.twitter.com/b4QHtnpxPd — Dr. Mathew Barlow (@MathewABarlow) January 17, 2022 Shockwave from Hunga Tonga-Hunga Haʻapai eruption plume, seen by pressure change at UK sites. Wave moves southward down the country 18-20Z 15Jan. The same wave, but travelling the other way around the globe, moves northward up the country 01-03Z 16Jan. @RoostWeather @Silkstiniho pic.twitter.com/2jXaWwyzih — Will Thurston (@imthursty) January 16, 2022 "The waves are red because of airglow, an aurora-like phenomenon caused by chemical reactions in the upper atmosphere. Airglow is usually too faint to see, but gravity waves from the volcano boosted the reaction rates." https://t.co/nntTFiBOrE https://t.co/qWinu9InSV — Justice (@Loveon999) January 18, 2022 Tonga volcano : This is shockwave as measured with the IASI satellite mission (temperature perturbation between the day of the eruption and the next day). First time we see this ! pic.twitter.com/7uTCwP3tNP — cathy clerbaux (@CathyClerbaux) January 19, 2022 Oopps! When a volcano erupts with such intensity in one part of the world and causes an #oilspill 10.000 km away. The Mare Doricum vessel was offloading at La Pampilla (Peru) refinery when the tsunami hit. Now, one of the worst oil disasters in the region. https://t.co/7nBNtWgX01 pic.twitter.com/MVPFGyIFWe — ᴄʀɪꜱᴛɪɴᴀ ᴠʀɪɴᴄᴇᴀɴᴜ 🌍🛰️ 🇪🇺 (@cavrinceanu) January 21, 2022 First simulation of the atmospheric pressure disturbances generated by the #Tonga volcano explosion compared with observations from different locations. Not bad results for a first guess.@IMEDEA_UIB_CSIC @UIBuniversitat pic.twitter.com/d26wmGiDJY — Angel Amores (@an_amores) January 21, 2022 Intriguing "halo" visible in @capellaspace radar image of #HungaTongaHungaHaapai submarine volcano. 🧐 Image acquired on 21 Jan. 2022 (03:32 UTC). Possible explanations: a/ submarine topography 🌋🌊 b/ winds & currents 💨 c/ residual heat 🔥 Thread! 🧵 (1/15) pic.twitter.com/tQOJj96lHu — Raphael Grandin (@RaphaelGrandin) January 25, 2022 Still going… https://t.co/6UCJJulbMh — Harold Tobin (@Harold_Tobin) January 25, 2022 Gemini Cloudcam Gravity Waves from Earth to Sky Calculus on Vimeo. .@scronin70 @patton_cascadia Just spotted the Liang et al paper on "Ice tongue calving in Antarctica triggered by the Hunga Tonga volcanic tsunami" https://t.co/Yepu8t7Ahm Appears @CopernicusEU #Sentinel3 #OCLI also caught the calving event. pic.twitter.com/CNZ2HHQhOR — DPManchee (@DPManchee) July 14, 2023 Below is an interactive map that displays a network of publicly accessible webcams that could be used to observe tsunami waves. A few days ago, I was passed out on my couch (sleep apnea) and for some reason I awoke and noticed that I had gotten a CSEM notification of a large earthquake offshore of Alaska. Well, after looking into that, I sent my boss, Rick, a text message: “8.2.” So let’s take a look at the things that may have affected the size of the tsunami from this 2021 M 8.2 earthquake. Below is an educational video from the USGS that presents material about subduction zones and the 1964 earthquake and tsunami in particular. This is a map from Haeussler et al. (2014). The region in red shows the area that subsided and the area in blue shows the region that uplifted during the earthquake. These regions were originally measured in the field by George Plafker and published in several documents, including this USGS Professional Paper (Plafker, 1969).
Above: Rupture zones of earthquakes of magnitude M > 7.4 from 1925-1971 as delineated by their aftershocks along plate boundary in Aleutians, southern Alaska and offshore British Columbia [after Sykes, 1971]. Contours in fathoms. Various symbols denote individual aftershock sequences as follows: crosses, 1949, 1957 and 1964; squares, 1938, 1958 and 1965; open triangles, 1946; solid triangles, 1948; solid circles, 1929, 1972. Larger symbols denote more precise locations. C = Chirikof Island. Below: Space-time diagram showing lengths of rupture zones, magnitudes [Richter, 1958; Kanamori, 1977 b; Kondorskay and Shebalin, 1977; Kanamori and Abe, 1979; Perez and Jacob, 1980] and locations of mainshocks for known events of M > 7.4 from 1784 to 1980. Dashes denote uncertainties in size of rupture zones. Magnitudes pertain to surface wave scale, M unless otherwise indicated. M is ultra-long period magnitude of Kanamori 1977 b; Mt is tsunami magnitude of Abe[ 1979]. Large shocks 1929 and 1965 that involve normal faulting in trench and were not located along plate interface are omitted. Absence of shocks before 1898 along several portions of plate boundary reflects lack of an historic record of earthquakes for those areas.
Proposed tectonic model for southern Chile. Partitioning of the oblique convergence vector between the Nazca plate and South American plate results in a dextral strike-slip fault zone in the magmatic arc and a northward moving forearc sliver. Modified after Lavenu and Cembrano (1999).
In 2016, there was an earthquake along the Alaska Peninsula, a M 7.1 on 2016.01.24. Here is my earthquake report for this earthquake. Here is a map for the earthquakes of magnitude greater than or equal to M 7.0 between 1900 and today. This is the USGS query that I used to make this map. One may locate the USGS web pages for all the earthquakes on this map by following that link. I plot tide gage data for gages in the north and northeast Pacific Ocean. These data are from NOAA Tides and Currents, though are also available via the eu tide gage website here. The scale for the tsunami wave height is on the right side of the chart. Below are surface deformation data generated by the USGS based on their finite fault model. The three panels show surface deformation in the north, east, and vertical directions. There are many different ways in which a landslide can be triggered. The first order relations behind slope failure (landslides) is that the “resisting” forces that are preventing slope failure (e.g. the strength of the bedrock or soil) are overcome by the “driving” forces that are pushing this land downwards (e.g. gravity). The ratio of resisting forces to driving forces is called the Factor of Safety (FOS). We can write this ratio like this: FOS = Resisting Force / Driving Force When FOS > 1, the slope is stable and when FOS < 1, the slope fails and we get a landslide. The illustration below shows these relations. Note how the slope angle α can take part in this ratio (the steeper the slope, the greater impact of the mass of the slope can contribute to driving forces). The real world is more complicated than the simplified illustration below.
Digitized marigrams from 1938 Alaskan earthquake recorded in Crescent City, San Diego, and San Francisco. The tidal componenht asn ot beenr emoved.S tartt ime listedf or each record is the time in minutes from the origin time of the earthquaketo the startt ime of the digitizedr ecord.
Location of subfaults used in inversion of tsunami waveforms. Graph shows slip distribution in meters.
Observed and synthetic waveforms from inversion for four subfaults. Start time of each record is different. The arrows indicate the parts of the waveforms used for the inversion.
Example slip distributions for two of the slip models, shallow eastern and shallow far eastern. For each model the slip is the product of a function f(x) representing the along-strike variation and g(y) representing the downdip variation, and then scaled to a constant magnitude MW 8.25. The functions f(x) and g(y) are based on relations in Freund and Barnett [1976]. For the central and western models, the rupture area is the same as for the eastern model, but the area of higher slip is shifted to the west. For the mid-depth and deep models, the main area of high slip is shifted downdip.
Vertical seafloor displacements caused by representative slip scenarios. On the left side, the slip is concentrated in the east and the deep, mid-depth and shallow slip distribution scenarios are shown. On the right, the Western, Central and Far Eastern slip distribution scenarios are shown assuming the shallow rupture. Displacements are in meters. Red contours show depth to the plate interface from 0 to 80 km with a 10 km increment.
Tide gauge data and model predictions for the eastern and far eastern source models.
Here is an animation from one of the Ferymueller et al. (2021) models for the 1938 M 8.2 tsunami.
A) Location of Chirikof Island within the plate tectonic setting of the Alaska-Aleutian subduction zone. Rupture areas for great twentieth century earthquakes on the megathrust are in pink. (B) Velocity field of the Alaska Peninsula and the eastern Aleutian Islands observed by global positioning system (GPS) (Fournier and Freymueller, 2007). Colors show inferred rupture areas for earthquakes in 1788 (green) and 1938 (orange). Both A and B are modified from Witter et al. (2014). The section of the megathrust between Kodiak Island and the Shumagin Islands has been referred to as the Semidi segment (e.g., Shennan et al., 2014b). (C) Physiography of Chirikof Island (Google Earth image, 2012) showing the location of our study area at Southwest Anchorage, a prominent moraine, a fault scarp (facing southeast) that probably records the 1880 earthquake, the New Ranch valley reconnaissance core site, and UNAVCO GPS station AC13 (http:// pbo .unavco .org /station /overview /AC13). In the eighteenth and nineteenth centuries, Chirikof Island was known to native Alutiiq and Russians as Ukamuk Island.
Age probability distributions for probable (red) and possible (orange) tsunami deposits at Southwest Anchorage (labels as in Fig. 11) compared with age distributions for possible tsunami deposits at Sitkinak Island (Briggs et al., 2014a) and with age estimates for great earthquakes and tsunamis on Kodiak Island (from studies referenced on this figure; #EarthquakeReport for M8.2 #Earthquake and probable #Tsunami offshore of #Alaskahttps://t.co/mFtEoigFQB read more about the tectonics herehttps://t.co/L4RHgNdex7 pic.twitter.com/Kgp6HxzSQ6 — Jason "Jay" R. Patton (@patton_cascadia) July 29, 2021 From @BNONews — Desianto F. Wibisono (@TDesiantoFW) July 29, 2021 #EarthquakeReport preliminary interpretive poster for M 8.2 #Earthquake #tsunami offshore of #Alaska in region 1938 M 8.2 generated #Tsunami with wave hts 5-10cm in #California (Johnson and Satake, '96)https://t.co/mFtEoigFQB — Jason "Jay" R. Patton (@patton_cascadia) July 29, 2021 Watch the waves from the M8.2 earthquake just offshore Alaska roll across the seismic stations in North America. (Credit @IRIS_EPO) pic.twitter.com/8qQeV4qBZY — Dr. Kasey Aderhold (@KaseyAderhold) July 29, 2021 Here's the #USGS MT for the recent M 8.2 on Fig. 1 of Freymueller et al. 2021 (https://t.co/FN8owbDqEY). Orange outline is aftershocks of the 1938 M 8.2. Red lines are 1 m contours of 1938 slip models. Grey is slip deficit inferred from geodesy. Obvious similarities 1938 -> 2021! pic.twitter.com/DIUh4YVhXc — Rich Briggs (@rangefront) July 29, 2021 UPDATE: The timing and form of this signal looks like it is the DART response to the seismic waves directly from the earthquake, NOT to a tsunami wave. pic.twitter.com/bxeF5TPqjv — Anthony Lomax 😷🇪🇺🌍 (@ALomaxNet) July 29, 2021 Small tsunami waves continue arriving at Sand Point & other coastal areas of Alaska. Tomorrow these waves will create swirly currents in boat harbors up & down the west coast, so tie up your boats real good. pic.twitter.com/nofvKqJoU5 — Brian Olson (@mrbrianolson) July 29, 2021 And since I have a drone workshop to attend tomorrow, I will bow out now and get some sleep. — Jascha Polet (@CPPGeophysics) July 29, 2021 @NOAA Tsunami Warning System has issued a tsunami watch for the West Coast. The warning for Hawaii has been cancelled, because the waves are focused east of Hawaii and the event isn't that large. @NWS_NTWC pic.twitter.com/h2KRBmOKNL — Dr. Lucy Jones (@DrLucyJones) July 29, 2021 A Tsunami Warning remains in effect. A Tsunami Advisory also remains in effect. pic.twitter.com/QLTiROkiri — NWS Anchorage (@NWSAnchorage) July 29, 2021 What a tsunami warning sounds like… they tested this earlier today too but this time is for real! M8.2, looks like on the subduction zone interface. (and look at those pretty peonies! 🌸) pic.twitter.com/1HPy8tBUC2 — Dr. Kasey Aderhold (@KaseyAderhold) July 29, 2021 Records of tsunami deposits show significant tsunamis in 1788, 1880 and 1938 (https://t.co/NsFfTuqigs), indicating recurrence intervals of large earthquakes in the Semidi segment every 58-92 years. We are now 83 years since 1938, so that seems roughly consistent. pic.twitter.com/CGIM40Fv0g — Dr Stephen Hicks 🇪🇺 (@seismo_steve) July 29, 2021 #EarthquakeReport for M 8.2 #Earthquake and #Tsunami offshore of #Alaska updated poster with Sand Point tide gage data@USGS_Quakes slip model — Jason "Jay" R. Patton (@patton_cascadia) July 29, 2021 Preliminary finite fault for this morning's M8.2 earthquake is available. Rupture primarily to the NE of the hypocenter, away from the Shumagin Gap.https://t.co/dVkYuR2kPC pic.twitter.com/idGBqxRhbX — Dr. Dara Goldberg (@dara_berg_) July 29, 2021 All #Tsunami alerts for the #Alaska coastline have been cancelled. Remember, strong and unusual currents may continue for several hours. If you have damage, please report it to your local officials. Stay safe, get some rest, and we'll keep the watch for you. Good night. https://t.co/wzUBu4ysK3 — NWS Tsunami Alerts (@NWS_NTWC) July 29, 2021 Tonight's M8.2 event occurred close to the rupture area of the 2020 M7.8 earthquake and was the largest U.S. earthquake in 50 years. We'll continue to update as this sequence unfolds, but here is a short piece on our website with what we know so far. https://t.co/PzHaaQ8Zbl pic.twitter.com/vcM8fq9IV7 — Alaska Earthquake Center (@AKearthquake) July 29, 2021 Some Perryville M 8.2 thoughts: One of the arresting things about Chirikof coastal geology is that the island is clearly sinking like a stone today, evident in geodesy and coastal geology. Figure from Nelson et al. 2015 https://t.co/vGKDp0WYuN *BUT* that isn't the entire story pic.twitter.com/LAWLqE1Su3 — Rich Briggs (@rangefront) July 29, 2021 The two closest sites to the M8.2 Alaska earthquake today show some decent surface wave signals. There are several other closer sites that should give us better insight. @UNAVCO pic.twitter.com/lN22i7arEP — Brendan Crowell (@bwcphd) July 29, 2021 8.2 Earthquake is the largest in Alaska since 1965. I was sitting in the upper wheelhouse of my 125' steel schooner ALEUTIAN EXPRESS at Chignik Harbor and the whole boat bounced and vibrated for about a minute. 14' range of gradual Tsunami one foot every 4 minutes both directions pic.twitter.com/IlYox48ejg — John Clutter (@AleutianExpress) July 29, 2021 Interesting look at the tide gauge in Eureka this morning. That perturbation over the last couple of hours is likely associated with the small tsunami waves from Alaska. This is a great reminder that tsunami danger can last well after the specific 'arrival time' #cawx pic.twitter.com/JloflW8aa5 — NWS Eureka (@NWSEureka) July 29, 2021 Additional Information about the M 8.2 earthquake that occurred 50 miles south of the Alaska Peninsula last night. https://t.co/2Jn2DLAV8M #Earthquake #Alaska pic.twitter.com/s1DDPmmaXG — USGS (@USGS) July 29, 2021 Alaska has a M7 earthquake every 2 years on average. So why the big deal about this M8.2? There is a BIG DIFFERENCE between a M7 and a M8. Use this “spaghetti magnitude” scale to visualize the difference. #AlaskaQuake pic.twitter.com/DT3tBzRkxs — Dr. Wendy Bohon (@DrWendyRocks) July 29, 2021 Preliminary Finite Fault Model of the Mw 8.2 Alaska event. @dara_berg_ @geosmx pic.twitter.com/WZNgmu9HWo — Sebastian Riquelme (@accelerogram) July 29, 2021 Clear NE propagation from the M8.2 in Alaska, but look at 102 sec- action to E way updip by the trench. Early aftershock or where rupture finally expired? It's small amplitude, but coherent and seen by 4 very different arrays. I await better analyses.https://t.co/6hFfZ64Elw pic.twitter.com/hacucSnOil — Alex Hutko (@alexanderhutko) July 29, 2021 Good morning all! The tsunami waves are still bouncing around the Aleutian Islands in Alaska (max height measured was ~2 feet). The tsunami turned out not to be very big & all @NWS_NTWC alerts for the US west coast are CANCELLED. 🚨NO alerts for CA, OR, WA. #earthquake pic.twitter.com/uEHSdzzvv9 — Brian Olson (@mrbrianolson) July 29, 2021 Waves from the recent M8.2 #Alaska #earthquake rolling through North America. Different colors correspond to different types of seismic waves. @IRIS_EPO pic.twitter.com/RJBlGh7zFg — UMN Seismology (@UMNseismology) July 29, 2021 Good morning PNW- ICYMI, last night there was a M8.2 earthquake off the Alaska Peninsula. Here, you can see waves from it (bottom) compared to a nearby Alaskan M6.8 (top, similar to our 2001 Nisqually M6.8) at station LEBA near the SW Washington coast. pic.twitter.com/GCCAjbYpII — PNSN (@PNSN1) July 29, 2021 Here I show the cross-section through the Alaska seismicity with projected mechanisms. The largest two events are yesterday's M8.2 quake and last year's M7.8, both subduction interface events. For reference, a cartoon of the shallow subduction zone from https://t.co/Gces1m71C8 pic.twitter.com/bgchTpPT5n — Jascha Polet (@CPPGeophysics) July 29, 2021 You may not have felt it, but a groundwater well in Washington County, Maryland did! An 8.2 magnitude earthquake rocked southern Alaska overnight and the water level in our well sloshed almost a foot. https://t.co/kafsMsaaph. For more real-time well data https://t.co/w56ACDNk4h pic.twitter.com/87fVSz0MLz — @USGS_MD_DE_DC (@USGS_MD_DE_DC) July 29, 2021 15 second sample rate data for AB13 is now available for the M8.2 Alaska earthquake, we see a pretty appreciable SE offset with 10 cm of subsidence. The event started NE of AC12 and ruptured to the NE, so this site is in the middle of it all. @UNAVCO pic.twitter.com/8nTTZstIDX — Brendan Crowell (@bwcphd) July 30, 2021 The largest earthquake to hit the U.S. in the last few decades took place in Alaska yesterday. The Mw 8.2 quake broke the Aleutian megathrust in the Shumagin seismic gap. The rupture did not propagate to the trench, causing only a minor tsunami. Figure by @QQtecGeodesy pic.twitter.com/02ylFet8P6 — Sylvain Barbot (@quakephysics) July 30, 2021 Recent Earthquake Teachable Moment for the M8.2 #AlaskaEarthquakehttps://t.co/2sFE9QDrNb pic.twitter.com/aLtYLIm61i — IRIS Earthquake Sci (@IRIS_EPO) July 30, 2021 14+ hours after the #alaska earthquake and there is still a tsunami bouncing around at the closest tide gauge (small tsunami) pic.twitter.com/3xtjS4hhge — Bill Barnhart (@SeismoSARus) July 29, 2021 There was a bit of confusion and misinformation with the Alaska earthquake last night, so how about us geoscientists put together a thread of seismologists/tsunami experts to follow. I'll start: @CPPGeophysics @SeismoSue @seismo_steve #Earthquake #alaskaearthquake pic.twitter.com/nfbQvfbnQy — Dr Janine Krippner (@janinekrippner) July 29, 2021 As of 12 hours following the M8.2 we've located ~140 aftershocks. The locations and magnitudes are subject to change upon further review, but look to be occurring to the east of 2020 sequence. The map here shows 2020 in gray and the recent aftershocks in red. pic.twitter.com/hQ93k7HVUZ — Alaska Earthquake Center (@AKearthquake) July 29, 2021 Last night's magnitude 8.2 earthquake serves as a powerful reminder of the restlessness of our planet's surface—and it presents an exciting opportunity to peer deeper at our planet’s inner workings. Learn more about Alaska's shakes in my latest @NatGeo https://t.co/gnPANhqWW1 — Dr. Maya Wei-Haas (@WeiPoints) July 29, 2021 Our event page for last night's M8.2 earthquake in Alaska is posted and will be updated as data are made available: https://t.co/XSq1nVyBuU pic.twitter.com/NcUqOKBdGT — UNAVCO (@UNAVCO) July 29, 2021 Slip contours for the July 2020 and 2021 megathrust #earthquakes One begins where the other ends. @bwcphd @dara_berg_ pic.twitter.com/URdqVX2r2R — Sean (@tsuphd) July 29, 2021 (1/3) The "Lame Monster": Today's largest US earthquake in >50 years did not make a large tsunami. Why? These are computer models of the tsunami from the M8.3 earthquake in Alaska#AlaskaQuake #alaskatsunami pic.twitter.com/QlJSWJMaqG — Amir Salaree (@amirsalaree) July 29, 2021 🌊The entire #California coast is a #tsunami hazard area. 🌊The July 27 M8.2 earthquake in #Alaska generated minor tsunami waves that are still being recorded on tide gages here. 🌊Head to ➡️https://t.co/UUkQsqYcAk to learn more about your tsunami risk. pic.twitter.com/pHjrTeOv5o — California Department of Conservation (@CalConservation) July 30, 2021 GPS receivers can be used as seismometers. In blue are the 5 Hz velocities recovered on Kodiak Island with the variometric approach for the M8.2 earthquake yesterday. In red, the collocated accelerometer, S19K, downsampled to 5 Hz. pic.twitter.com/jxJR1v7Fj1 — Brendan Crowell (@bwcphd) July 30, 2021 A notable characteristic of the M8.2 Alaska earthquake is that it was relatively deep and doesn’t appear to have ruptured the shallow plate boundary. Could overpressured sediments on the shallow plate boundary inhibited shallow slip? Check out this seismic image updip of event. pic.twitter.com/HRQEPxrAZk — Donna Shillington (@djshillington) July 30, 2021 We finally have some preliminary coseismic offsets for the M8.2 Alaska earthquake. AB13 has a 43 cm offset to the SE. pic.twitter.com/RSttwW4nBl — Brendan Crowell (@bwcphd) July 30, 2021 While the M8.2 was the largest earthquake in the U.S. in 50 years, Alaska has experienced some significantly sized events during that time. The plot here shows the largest Alaska earthquake magnitude each year since 1964. Since 2000, we're experienced at least a M6.4 annually. pic.twitter.com/Iq9pFanPqi — Alaska Earthquake Center (@AKearthquake) July 30, 2021 Whopper M8.2 earthquake in Alaska moved GPS stations, revealing the broad pattern and extent of deformation. — Bill Hammond (@BillCHammond) July 30, 2021 (1/6) DART Seismology: How the tsunami sensors near Alaska picked up the seismic surface waves from the M8.3 Alaska earthquake! The tails in the records are mixes of surface waves and the tsunami.#alaskaearthquake #alaska_tsunami @NOAAResearch @NWS_PTWC @IRIS_EPO pic.twitter.com/OWI7e47dNq — Amir Salaree (@amirsalaree) July 31, 2021 #EarthquakeReport and #TsunamiReport for M8.2 #Earthquake offshore of #Alaska updated interpretive poster '21 sequence matches '38 sequence for both ~slip patch and ~tsunami size https://t.co/pE3zA9HHFShttps://t.co/mFtEoigFQB — Jason "Jay" R. Patton (@patton_cascadia) August 2, 2021 #Sentinel1 co-seismic interferograms (ascending track) over western Alaska, show ground deformation towards the southern coast, above the main M8.2 #earthquake fault rupture. Aftershock epicenters (yellow) from USGS. pic.twitter.com/RtavuJZGSZ — Sotiris Valkaniotis (@SotisValkan) August 2, 2021 The M 8.2 Chignik earthquake that occurred off the Alaskan Peninsula on July 28 was the largest US earthquake in 50 years. This 2013 simulation from the same region shows how a hypothetical M 9.1 (almost 30x stronger!) earthquake can create a far-reaching tsunami. @USGS_Quakes pic.twitter.com/tLtxWxoal7 — USGS Coastal Change (@USGSCoastChange) July 30, 2021 Updated finite fault model (joint inversion of regional and teleseismic data) is now available: https://t.co/K0kXumE6Pv pic.twitter.com/y7Z9vIF6Lu — Dr. Dara Goldberg (@dara_berg_) August 3, 2021 #EarthquakeReport & #TsunamiReport for M8.2 Perrysville #Earthquake and transpacific #Tsunami updated poster including @USGS_Quakes @dara_berg_ updated slip model also, surface deformation data I prepared a report and will update morehttps://t.co/y1RwyZjKOA pic.twitter.com/lj8qIk7vQl — Jason "Jay" R. Patton (@patton_cascadia) August 4, 2021
This year we look back and remember what happened ten years ago in Japan and across the entire Pacific Basin. Here are all the pages for this earthquake and tsunami: I have several reports from previous years that have reviews of the earthquake and tsunami. I focus mostly on new material I prepared for the following report. Use this map to see the magnitudes of different earthquakes experienced in Japan. The map shows earthquake epicenters for large-magnitude historic events of the past century. It also includes epicenters for all aftershocks and triggered earthquakes for a year after the M 9.1 earthquake, and an outline of the aftershocks, which illustrates the area of the fault that slipped during the M 9.1 earthquake. Earthquake intensity is a measure of how strongly earthquake shaking is felt by people and objects. The further away from the epicenter, the lower the earthquake intensity. Seismologists use computer models to estimate what the intensity will be from an earthquake. The U.S. Geological Survey uses its “Did You Feel It?” (DYFI) system to collect observations about how strongly people in different places felt an earthquake. Use this map to see the level of intensity people felt in different parts of Japan. The map displays the USGS intensity model for the M 9.1 earthquake as transparent colors. The map also shows, as colored circles, the “Did You Feel It?” report results from people who experienced shaking from this earthquake. Tsunami can be caused by a variety of processes, including earthquakes, volcanic eruptions, landslides, and meteorological phenomena. Earthquakes, eruptions, and landslides cause tsunami when these processes displace water in some way. We may typically associate tsunami with subduction zone earthquakes because these earthquakes are the type that generate vertical land motion along the sea floor. Use this map to see tsunami wave data as recorded by tide gages across the entire Pacific Basin. Click on a white triangle and there is a link to open the tide gage data as a graphic. There are many different ways in which a landslide can be triggered. The first order relations behind slope failure (landslides) is that the “resisting” forces that are preventing slope failure (e.g. the strength of the bedrock or soil) are overcome by the “driving” forces that are pushing this land downwards (e.g. gravity). The ratio of resisting forces to driving forces is called the Factor of Safety (FOS). We can write this ratio like this: FOS = Resisting Force / Driving Force When FOS > 1, the slope is stable and when FOS < 1, the slope fails and we get a landslide. The illustration below shows these relations. Note how the slope angle α can take part in this ratio (the steeper the slope, the greater impact of the mass of the slope can contribute to driving forces). The real world is more complicated than the simplified illustration below. #EarthquakeReport for #OTD 2011 M9.1 Tōhoku-oki #Earthquake #Tsunami #Landslides decade remembrance with some updated maps and web maps report here:https://t.co/n5UI6Co1iv main report w/tectonic details:https://t.co/0jo9XuHxdE pic.twitter.com/MkEAbQkTXe — Jason "Jay" R. Patton (@patton_cascadia) March 11, 2021 #EarthquakeReport #OTDearthquake 2011.03.11 M 9.0 Tohoku-oki earthquake and tsunami. #JapanEarthquake first observed 50+ m slip, fault offset at trench, heatflow from fault-slip friction, triggered outer-rise EQs etc. Many discoveries MORE here:https://t.co/0jo9XuHxdE pic.twitter.com/6gNFZWitDn — Jason "Jay" R. Patton (@patton_cascadia) March 11, 2018
Well, it has been a busy couple of weeks. https://earthquake.usgs.gov/earthquakes/eventpage/us6000ah9t/executive The west coast coastline of southern Mexico, Central America, and South America is formed by a convergent plate boundary where oceanic tectonic plates dive eastwards beneath the continents. The fault formed at this plate boundary is called a subduction zone and the dynamics of subduction zones form deep sea trenches. I spend a few paragraphs discussing the different faults that form at different plate boundaries here. Offshore of southern Mexico the Middle America trench shows us the location of the subduction zone megathrust fault. This fault system has a long history of damaging earthquakes, including some events that affect areas hundreds of kilometers from the source earthquake (e.g. the 1985 magnitude M 8 Mexico City earthquake). In the past few years, evidences this megathrust is active continue to present themselves. There is a list of some earthquake reports at the bottom of this page. The earthquake generated seismic waves that travelled around the world, including some that caused strong shaking in Mexico City. Mexico City was built where the Aztec Civilization had once constructed a great city. This city was built next to a lake where the Aztec constructed floating gardens. Eventually, these gardens filled the lake and the lake filled with sediment (I am simplifying what happened over a long time). So, Mexico City is built in a sedimentary basin. Sedimentary basins can amplify shaking from seismic waves. These basins can also focus seismic waves and these waves can resonate within the basin, causing further amplification. This is why there was so much damage in Mexico City from the 1985 subduction zone earthquake. The same thing happened a couple years ago for a recent earthquake there. Well, when subduction zone earthquakes happen, the crust around the fault can flex like the elastic on one’s waist band. As the crust moves, if that crust is beneath the water, this crust motion moves the water causing a tsunami. There are a number of organizations that monitor the Earth for earthquakes that may cause tsunami. These organizations alert officials in regions where these tsunami may inundate so that residents and visitors to the coast can take action (e.g. head to high ground). These programs save lives. This M 7.4 earthquake generated a tsunami that was recorded along the coastline, but not at all tide gage stations. The Salina Cruz station has a great record of this tsunami and is located >80 km from the epicenter. The Acapulco station also recorded a tsunami, but those data were not uploaded to the IOC website (they are working this out now). It appeared that the Acapulco data were being streamed in real time, but I noticed that they were the same data as posted for the Salina Cruz station. Here I plot the water surface elevations observed at the Salina Cruz tide gage. I mark the earthquake event time and the tsunami arrival time, then calculate the tsunami travel time. The Wave Height of the tsunami is the vertical distance measured between the peak and the trough. These data show a Maximum Wave Height of 1.4 meters. The strong ground shaking from an earthquake can also cause landslides and liquefaction. I discuss these further down in this report and include maps in the poster.
Tectonic setting of the Caribbean Plate. Grey rectangle shows study area of Fig. 2. Faults are mostly from Feuillet et al. (2002). PMF, Polochic–Motagua faults; EF, Enriquillo Fault; TD, Trinidad Fault; GB, Guatemala Basin. Topography and bathymetry are from Shuttle Radar Topography Mission (Farr&Kobrick 2000) and Smith & Sandwell (1997), respectively. Plate velocities relative to Caribbean Plate are from Nuvel1 (DeMets et al. 1990) for Cocos Plate, DeMets et al. (2000) for North America Plate and Weber et al. (2001) for South America Plate.
A. Geodynamic and tectonic setting alongMiddle America Subduction Zone. JB: Jalisco Block; Ch. Rift—Chapala rift; Co. rift—Colima rift; EGG—El Gordo Graben; EPR: East Pacific Rise; MCVA: Modern Chiapanecan Volcanic Arc; PMFS: Polochic–Motagua Fault System; CR—Cocos Ridge. Themain Quaternary volcanic centers of the TransMexican Volcanic Belt (TMVB) and the Central American Volcanic Arc (CAVA) are shown as blue and red dots, respectively. B. 3-D view of the Pacific, Rivera and Cocos plates’ bathymetrywith geometry of the subducted slab and contours of the depth to theWadati–Benioff zone (every 20 km). Grey arrows are vectors of the present plate convergence along theMAT. The red layer beneath the subducting plate represents the sub-slab asthenosphere.
Kinematic model (mantle reference frame) of the subducting Cocos slab along the MAT in the vicinity of Cocos–Caribbe–North America triple junction since Early Miocene. The evolution of Caribbean–North America tectonic contact is based on the model of Witt et al. (2012). The blue strips represent markers on the Cocos plate. Note how trench roll forward is associated with steep slab in Central America, whereas trench roll back is associated with flat slab in Mexico.
Marine magnetic anomalies and fracture zones that constrain tectonic reconstructions such as those shown in Figure 4 (ages of anomalies are keyed to colors as explained in the legend; all anomalies shown are from University of Texas Institute for Geophysics PLATES [2000] database): (1) Boxed area in solid blue line is area of anomaly and fracture zone picks by Leroy et al. (2000) and Rosencrantz (1994); (2) boxed area in dashed purple line shows anomalies and fracture zones of Barckhausen et al. (2001) for the Cocos plate; (3) boxed area in dashed green line shows anomalies and fracture zones from Wilson and Hey (1995); and (4) boxed area in red shows anomalies and fracture zones from Wilson (1996). Onland outcrops in green are either the obducted Cretaceous Caribbean large igneous province, including the Siuna belt, or obducted ophiolites unrelated to the large igneous province (Motagua ophiolites). The magnetic anomalies and fracture zones record the Cenozoic relative motions of all divergent plate pairs infl uencing the Central American subduction zone (Caribbean, Nazca, Cocos, North America, and South America). When incorporated into a plate model, these anomalies and fracture zones provide important constraints on the age and thickness of subducted crust, incidence angle of subduction, and rate of subduction for the Central American region. MCSC—Mid-Cayman Spreading Center.
Present setting of Central America showing plates, Cocos crust produced at East Pacifi c Rise (EPR), and Cocos-Nazca spreading center (CNS), triple-junction trace (heavy dotted line), volcanoes (open triangles), Middle America Trench (MAT), and rates of relative plate motion (DeMets et al., 2000; DeMets, 2001). East Pacifi c Rise half spreading rates from Wilson (1996) and Barckhausen et al. (2001). Lines 1, 2, and 3 are locations of topographic and tomographic profi les in Figure 6.
(A) Tomographic slices of the P-wave velocity of the mantle at depths of 100, 300, and 500 km beneath Central America. (B) Upper panels show cross sections of topography and bathymetry. Lower panels: tomographic profi les showing Cocos slab detached below northern Central America, upper Cocos slab continuous with subducted plate at Middle America Trench (MAT), and slab gap between 200 and 500 km. Shading indicates anomalies in seismic wave speed as a ±0.8% deviation from average mantle velocities. Darker shading indicates colder, subducted slab material of Cocos plate. Circles are earthquake hypocenters. Grid sizes on profi les correspond to quantity of ray-path data within that cell of model; smaller boxes indicate regions of increased data density. CT—Cayman trough; SL—sea level (modifi ed from Rogers et al., 2002).
Rupture zones (ellipses) and epicenters (triangles and circles) of large shallow earthquakes (after KELLEHER et al., 1973) and bathymetry (CHASE et al., 1970) along the Middle America arc. Note that six gaps which have earthquake histories have not ruptured for 40 years or more. In contrast, the gap near the intersection of the Tehuantepec ridge has no known history of large shocks. Contours are in fathoms.
The study area encompasses Guerrero and Oaxaca states of Mexico. Shaded ellipse-like areas annotated with the years are rupture areas of the most recent major thrust earthquakes (M≥6.5) in the Mexican subduction zone. Triangles show locations of permanent GPS stations. Small hexagons indicate campaign GPS sites. Arrows are the Cocos-North America convergence vectors from NUVEL-1A model (DeMets et al., 1994). Double head arrow shows the extent of the Guerrero seismic gap. Solid and dashed curves annotated with negative numbers show the depth in km down to the surface of subducting Cocos plate (modified from Pardo and Su´arez, 1995, using the plate interface configuration model for the Central Oaxaca from this study, the model for Guerrero from Kostoglodov et al. (1996), and the last seismological estimates in Chiapas by Bravo et al. (2004). MAT, Middle America trench.
Tectonic framework of the Cocos plate convergent margin. Top- General view. Yellow arrows indicate direction and speed (in cm/yr) of plate convergence, calculated from the Euler poles given by DeMets et al. (2010) for CocoeNoam (first three arrows, from left to right), and CocoeCarb (last four arrows). Length of arrow is proportional to speed. Red arrow shows location of the 96 longitude. Box indicates location of lower panel. Bottom- Location of features and places mentioned in text. Triangles indicate volcanoes of the Central American Volcanic Arc (CAVA) with known Holocene eruption (Siebert and Simkin, 2002).
Seismicity along the convergent margin. Top: Map view. Blue circles are shallow (z < 60 km) hypocenters; orange, intermediate-depth (60 < z < 100 km); yellow, deep (z > 100 km). Next three panels: Earthquakes as a function of longitude and magnitude for shallow (blue dots), intermediate (orange), and deep (yellow) hypocenters. Numbers indicate number of events on each convergent margin, with average magnitude in parenthesis. Gray line in this and subsequent figures mark the 96 deg longitude.
Location of hypocentral cross-sections. Hypocentral depths are keyed as in previous figures.
Hypocentral cross-sections. Depths are color-coded as in previous figures. Dashed lines indicate the 60-km and 100-km depths. Tick marks are at 100-km intervals, as shown on the sections. There is no vertical exaggeration and Earth’s curvature is taken into account. Number of sections refers to location on Fig. 3.
Earthquake fault-plane solutions from CMT data. a. Shallow (z < 60 km), thrust-faulting mechanisms. b. Intermediate-depth (60 < z < 100 km) thrust-faulting events. c. Deep (z > 100 km), thrust-faulting earthquakes. d. to f. Normal-faulting events, in same layout as for thrust-faulting events.
FOS = Resisting Force / Driving Force #EarthquakeReport in Mexico for M 7.4 #Earthquake #Terremoto be safe everyonehttps://t.co/jTfZEjQ0H0 more on tectonic background herehttps://t.co/5jgHU1xxbx pic.twitter.com/H1moPjQtqR — Jason "Jay" R. Patton (@patton_cascadia) June 23, 2020 #EarthquakeReport for the M 7.4 #Terremoto #Earthquake #Tsunami in #Oaxaca #Mexico shaking felt in #MexicoCity poster previously posted is updated and explained in report here:https://t.co/jCM8vu0ccX pic.twitter.com/C7OD8UobyL — Jason "Jay" R. Patton (@patton_cascadia) June 25, 2020 Watch the waves from the M7.4 Mexico earthquake roll across seismic stations in North America! (THREAD) pic.twitter.com/7dpPr1Ueuy — IRIS Earthquake Sci (@IRIS_EPO) June 23, 2020 Tide gauge at Salina Cruz, Mexico#SantaMaríaZapotitlán for M7.4 earthquake. pic.twitter.com/RNVYbzxseM — Nick Graehl (@nickgraehl) June 23, 2020 #Terremoto en México: en estas impactantes imágenes, tomadas en Bosques de las Lomas (#CDMX), podemos observar como ambos lados de una grieta se mueven ligeramente durante el seísmo.pic.twitter.com/u50mCx1XFS — eSPAINews (@eSPAINews) June 23, 2020 Heres my first cut at estimating offsets for the event today in Mexico. I will add more sites as they become available. The mechanism is USGS W-phase. pic.twitter.com/PomjZF0JKL — Brendan Crowell (@bwcphd) June 23, 2020 #Earthquake_alert – Source: @Bersa76#CDMX Así se sintió el sismo en el nivel 56 de la Torre Mitikah en la alcaldía Benito Juárez, se trata de un inmueble de 267.3m de altura. pic.twitter.com/J6cpAZfPIU#Mexico #earthquake #alert #warning #mitigation #tsunami — Desianto F. Wibisono (@TDesiantoFW) June 23, 2020 VIDEO: A building swaying in Mexico City’s La Condesa neighborhood, after today’s 7.4 quake in southern Mexico, according to @TVVnoticias pic.twitter.com/BKJrilJZ8s — Manuel Bojorquez (@BojorquezCBS) June 23, 2020 "Nearly" automatic forward model based on the USGS focal mechanism for the M 7.4 #Mexico #earthquake (June 22, 15:29 UTC). And expected InSAR fringe pattern from C-band ascending orbit. Waiting, as usual, for real InSAR data. — Simone Atzori (@SimoneAtzori73) June 23, 2020 #DÚltimaHora #D7 Cerrada la Carretera Oaxaca-Istmo por Derrumbe en las Cercanías de la Comunidad del Camarón, evite Viajar más información en un momento. pic.twitter.com/B3G5b17YZv — Domingo 7 (@domingo7th) June 23, 2020 A 7.4 magnitude #earthquake has hit the southern coastline of #Mexico. #Sismo #Temblor #Oaxaca #CDMX #AlertaSismica pic.twitter.com/doiICbJHuy — DailyNewsf (@DailyNe25683877) June 23, 2020 #sismo2020 #sismo | En la Roma Norte, el movimiento causó daños en la azotea de una edificio, del cual comenzaron a caer chorros de agua pic.twitter.com/LqA4fVKhBy — RedTvo Television (@redtvo) June 23, 2020 El #sismo magnitud 7.1 con epicentro en Crucecita Huatulco, #Oaxaca. Ocasionó daños en el Centro Histórico de la Capital. pic.twitter.com/iD70elgxP1 — Diario El Fortín (@diarioelfortin) June 23, 2020 En la zona platanera de Teapa, Tabasco, así se percibió el sismo de 7.5 #CDMX #oaxaca pic.twitter.com/sgpd4lKvOs — Desde Peninsula (@DesdePeninsula) June 23, 2020 Playa Riscalillo, mar se aleja unos cien metros. Bahía principal de Huatulco, mar se aleja unos 30-40 metros#ReporteCiudadano#TenemosSismo #Oaxaca #Huatulco pic.twitter.com/rZNa5AWDFr — Periodistas Oaxaca (@PeriodistasOax) June 23, 2020 OXUM roughly 75 km away to the west had pretty sizable vertical motions. pic.twitter.com/YIltT3uBE4 — Brendan Crowell (@bwcphd) June 23, 2020 Así se sintió el sismo de 7.5 está mañana en Xochimilco pic.twitter.com/yK0CCKwGNt — Salvador García Soto (@SGarciaSoto) June 23, 2020 Earthquake in Mexico City- still occurring – not sure where epicenter is nor if there is any real damage pic.twitter.com/KDAou9YhPG — (@Andalalucha) June 23, 2020 First rough model of the tsunami from today's M7.5 earthquake in Mexico using the USGS finite fault as input. Clear edgewaves and shelf resonance in the Tehuantepec gulf. https://t.co/2FAV5m81ZX — Diego Melgar (@geosmx) June 23, 2020 Today's Oaxaca tsunami in the Pacific. So far, only on 43413… pic.twitter.com/hDqG2ip3jI — Amir Salaree (@amirsalaree) June 23, 2020 El 23 de junio del 2020, un terremoto M7.4 cerca de Oaxaca, México, ocurrió como resultado de una falla inversa en o cerca del límite de la placa que está entre las placas de Cocos y América del Norte. (Enlaces y detalles: https://t.co/qvcse5eYQe) pic.twitter.com/53IxlOr0VG — USGS (@USGS) June 23, 2020 A section from today's M7.4 earthquake near Santa María Zapotitlán at 2020-06-23 15:29:05 UTC recorded on the worldwide @raspishake network and processed with a wider frequency range than I normally use. See: https://t.co/44McZsCCpE. Uses @obspy & @matplotlib software. pic.twitter.com/kItaJfsJ4W — Mark Vanstone (@wmvanstone) June 23, 2020 GSN and other global surface & body wave record sections for the M7.4 Mexico earthquake https://t.co/FvU7Jlak3R pic.twitter.com/YdvRb3iInc — IRIS Earthquake Sci (@IRIS_EPO) June 23, 2020 How big was that magnitude 7.4 earthquake? According to my calculations (see below), it's as if about 4 trillion college students jumped about 1 ft. And, that's about 500 times the population of planet Earth! (Peer review of my calculations is welcome…) pic.twitter.com/TlrmXhQSLj — Alan Kafka (@Weston_Quakes) June 24, 2020 #Mexico M7.4 #earthquake — Vincenzo De Novellis (@VDN75) June 24, 2020 #ERCC #DailyMap: 2020-06-24 ⦙ Mexico | 7.4M Earthquake of 23 June ▸https://t.co/mdRq0Me6LL pic.twitter.com/z7vgXVrfRG — Copernicus EMS (@CopernicusEMS) June 24, 2020 I find it mightily impressive that the low-cost geophone sensors inside @raspishake seismometers were able to capture the long-period surface wave signals, as well as higher-freq body waves, from yesterday's M7.4 Mexico earthquake. — Stephen Hicks (@seismo_steve) June 24, 2020
It was a busy week (usual, right?). The previous week I was working on getting a house remodel done so someone could move in (they have been sleeping on couches for 6 months, so want to get them in asap). This week I spent lots of time putting final touches on a USGS National Earthquake Hazards Reduction Program external grant proposal together, proposing to conduct a paleoseismic investigation for a fault I discovered in late 2018 (see AGU poster here). So, I am catching up on my earthquake reporting for this earthquake offshore northern California. More about different types of faults can be found here.
A: Mapped faults and fault-related ridges within Gorda plate based on basement structure and surface morphology, overlain on bathymetric contours (gray lines—250 m interval). Approximate boundaries of three structural segments are also shown. Black arrows indicated approximate location of possible northwest- trending large-scale folds. B, C: uninterpreted and interpreted enlargements of center of plate showing location of interpreted second-generation strike-slip faults and features that they appear to offset. OSC—overlapping spreading center.
Models of brittle deformation for Gorda plate overlain on magnetic anomalies modified from Raff and Mason (1961). Models A–F were proposed prior to collection and analysis of full-plate multibeam data. Deformation model of Gulick et al. (2001) is included in model A. Model G represents modification of Stoddard’s (1987) flexural-slip model proposed in this paper.
Tectonic configuration of the Gorda deformation zone and locations and source models for 1976–2010 M ≥ 5.9 earthquakes. Letters designate chronological order of earthquakes (Table 1 and Appendix A). Plate motion vectors relative to the Pacific Plate (gray arrows in main diagram) are from Wilson [1989], with Cande and Kent’s [1995] timescale correction.
The Gorda and Juan de Fuca plates subduct beneath the North America plate to form the Cascadia subduction zone fault system. In 1992 there was a swarm of earthquakes with the magnitude Mw 7.2 Mainshock on 4/25. Initially this earthquake was interpreted to have been on the Cascadia subduction zone (CSZ). The moment tensor shows a compressional mechanism. However the two largest aftershocks on 4/26/1992 (Mw 6.5 and Mw 6.7), had strike-slip moment tensors. These two aftershocks align on what may be the eastern extension of the Mendocino fault. Well, it was a big mag 5 day today, two magnitude 5+ earthquakes in the western USA on faults related to the same plate boundary! Crazy, right? The same plate boundary, about 800 miles away from each other, and their coincident occurrence was in no way related to each other. I was on the phone with my friend, collaborator, and business partner Thomas Harvey Leroy (the man with 4 first names: Tom, Harvey, Lee, and Roy) yesterday afternoon. We were determining the best course of action after a tenant of ours moved out leaving PG&E with an unpaid ~$9000 bill and we could not turn the power back on until the bill was paid. His son walked up to him and asked if what he had just felt was an earthquake. Because Tom was pacing back and forth, he did not feel it (as Tom likes to say, “feel the pain.”). He wishes that he had felt it. Well, they are not directly related to each other (i.e. none of these earthquakes caused any of the other earthquakes). The exception is that the 2019 M 5.6 may have affected the stress in the crust leading to the March M 5.2, but this is unlikely. What is even less likely that the M 5.8 was caused by the June 5.6 or caused the march 5.2. Below is a figure from Wells and Coppersmith (1994) that shows the empirical relations between surface rupture length (SRL, the length of the fault that ruptures to the ground surface) and magnitude. If one knows the SRL (horizontal axis), they can estimate the magnitude (vertical axis). The left plot shows the earthquake data. The right plot shows how their formulas “predict” these data.
(a) Regression of surface rupture length on magnitude (M). Regression line shown for all-slip-type relations. Short dashed line indicates 95% confidence interval. (b) Regression lines for strike-slip, reverse, and normal-slip relations. See Table 2 for regression coefficients. Length of regression lines shows the range of data for each relation. Using these empirical relations (which are crude and may not cover earthquakes as small as this M 5.8, but they are better than nothing), the “surface rupture length” of this M 5.8 might be about 5 km. So, changes in static coulomb stress from the M 5.8 extended, at most, about 16 km (or about 10 miles). Yesterday’s M 5.2. is about 72 km away, far too distant to be statically triggered by the 5.8. I also outlined the two main northwest trends in seismicity with dashed white line polygons. The 18 March event is in the southern end of the western seismicity trend.
The Gorda and Juan de Fuca plates subduct beneath the North America plate to form the Cascadia subduction zone fault system. In 1992 there was a swarm of earthquakes with the magnitude Mw 7.2 Mainshock on 4/25. Initially this earthquake was interpreted to have been on the Cascadia subduction zone (CSZ). The moment tensor shows a compressional mechanism. However the two largest aftershocks on 4/26/1992 (Mw 6.5 and Mw 6.7), had strike-slip moment tensors. In my mind, these two aftershocks aligned on what may be the eastern extension of the Mendocino fault. However, looking at their locations, my mind was incorrect. These two earthquakes were not aftershocks, but were either left-lateral or right-lateral strike-slip Gorda plate earthquakes triggered by the M 7.1 thrust event.
Tectonic configuration of the Gorda deformation zone and locations and source models for 1976–2010 M ≥ 5.9 earthquakes. Letters designate chronological order of earthquakes (Table 1 and Appendix A). Plate motion vectors relative to the Pacific Plate (gray arrows in main diagram) are from Wilson [1989], with Cande and Kent’s [1995] timescale correction.
A: Mapped faults and fault-related ridges within Gorda plate based on basement structure and surface morphology, overlain on bathymetric contours (gray lines—250 m interval). Approximate boundaries of three structural segments are also shown. Black arrows indicated approximate location of possible northwest- trending large-scale folds. B, C: uninterpreted and interpreted enlargements of center of plate showing location of interpreted second-generation strike-slip faults and features that they appear to offset. OSC—overlapping spreading center.
Models of brittle deformation for Gorda plate overlain on magnetic anomalies modified from Raff and Mason (1961). Models A–F were proposed prior to collection and analysis of full-plate multibeam data. Deformation model of Gulick et al. (2001) is included in model A. Model G represents modification of Stoddard’s (1987) flexural-slip model proposed in this paper.
If we move a little further north, we can take a look at the Blanco fault. This is a right-lateral strike-slip fault just like the Mendocino and San Andreas faults.
(Top) Sea Beam bathymetric map of the Cascadia Depression, Blanco Ridge, and Gorda Depression, eastern Blanco Transform Fault Zone (BTFZ).Multibeam bathymetry was collected by the NOAA R/V’s Surveyor and Discoverer and the R/V Laney Chouest during 12 cruises in the 1980’s and 90’s. Bathymetry displayed using a 500 m grid interval. Numbers with arrows show look directions of three-dimensional diagrams in Figures 2 and 3. (Bottom) Structure map, interpreted from bathymetry, showing active faults and major geologic features of the region. Solid lines represent faults, dashed lines are fracture zones, and dotted lines show course of turbidite channels. When possible to estimate sense of motion on a fault, a filled circle shows the down-thrown side. Inset maps show location and generalized geologic structure of the BTFZ. Location of seismic reflection and gravity/magnetics profiles indicated by opposing brackets. D-D’ and E-E’ are the seismic reflection profiles shown in Figures 8a and 8b, and G-G’ is the gravity and magnetics profile shown in Figure 13. Submersible dive tracklines from sites 1 through 4 are highlighted in red. L1 and L2 are two lineations seen in three-dimensional bathymetry shown in Figures 2 and 3. Location of two Blanco Ridge slump scars indicated by half-rectangles, inferred direction of slump shown by arrow, and debris location (when identified) designated by an ‘S’. CD stands for Cascadia Depression, BR is Blanco Ridge, GD is Gorda Depression, and GR is Gorda Ridge. Numbers on north and south side of transform represent Juan de Fuca and Pacific plate crustal ages inferred from magnetic anomalies. Long-term plate motion rate between the Pacific and southern Juan de Fuca plates from Wilson (1989).
When there are quakes on the BF, people always wonder if the Cascadia megathrust is affected by this… “are we at greater risk because of those BF earthquakes?” As I was waking up this morning, I rolled over to check my social media feed and moments earlier there was a good sized shaker in Salt Lake City, Utah. I immediately thought of my good friend Jennifer G. who lives there with her children. I immediately started looking into this earthquake. The west coast of the United States and Mexico is dominated by the plate boundary between the Pacific and North America plates. Many are familiar with the big players in this system: There are many other faults that are also part of this plate boundary system. The San Andreas fault zone “proper” accommodates about 85% of the relative plate motion. The rest of the relative plate motion (15%) is accounted for by slip on other strike-slip fault systems.
Central segments of the WFZ (red), which have evidence of repeated Holocene surface-faulting earthquakes. Circles indicate sites with data that we reanalyzed using OxCal (abbreviations shown in Table 2); triangles indicate sites where data or documentation was inadequate for reanalysis (HC, Hobble Creek; PP, Pole Patch; WC, Water Canyon; WH, Woodland Hills). Other Quaternary faults in northern Utah (white lines) include the ECFZ, East Cache fault zone; OGSLFZ, Oquirrh Great Salt Lake fault zone; ULFF, Utah Lake faults and folds; WVFZ, West Valley fault zone. Fault traces are from Black et al. [2003]. Horizontal bars mark primary segment boundaries. Inset map shows the trace of the WFZ in northern Utah and southern Idaho.
Late Holocene surface-faulting earthquakes identified at trench sites along the central WFZ. Circles with labels indicate sites with data that were reanalyzed using OxCal, and unlabeled white triangles indicate sites where data or documentation was inadequate for reanalysis. Distance is measured along simplified fault trace (dash dotted line) shown in top panel. Individual earthquake-timing probability density functions (PDFs) and mean times are derived from OxCal models for the paleoseismic sites; number in brackets is event number, where one is the youngest.
FOS = Resisting Force / Driving Force When FOS > 1, the slope is stable and when FOS < 1, the slope fails and we get a landslide. The illustration below shows these relations. Note how the slope angle α can take part in this ratio (the steeper the slope, the greater impact of the mass of the slope can contribute to driving forces). The real world is more complicated than the simplified illustration below. — Jason "Jay" R. Patton (@patton_cascadia) March 19, 2020 This 3-D representation shows earthquake locations of the 03/18/20, Magna sequence. The largest circle is the magnitude 5.7 main shock, at a depth of about 7.5 miles (12 km), and the other circles are aftershocks that had occurred through 1:30 pm MDT.https://t.co/5YuwS7G8Rm pic.twitter.com/uPDuoiRX3l — Utah Geological (@utahgeological) March 18, 2020 UGS geologists are on the ground documenting the geologic effects of today's earthquakes. More information will be added as our field teams continue their investigations.https://t.co/0U7ga954RD#utahearthquake pic.twitter.com/La1oJnIIhy — Utah Geological (@utahgeological) March 19, 2020
I was in Humboldt County last week for the Redwood Coast Tsunami Work Group meeting. I stayed there working on my house that a previous tenant had left in quite a destroyed state (they moved in as friends of mine). Here is a seismic selfie from Riley, a student at Humboldt State University (taking a geology course). This photo was posted on the HSU Dept. of Geology facebook page.
Earthquake Report: M 6.0 northeast Pacific Ocean
Below is my interpretive poster for this earthquake
I include some inset figures.
Pacific Ocean | Hawai’i’ Earthquake Reports
References:
Basic & General References
Specific References
Return to the Earthquake Reports page.
Tsunami Report: Hunga Tonga-Hunga Ha’apai Volcanic Eruption & Tsunami
Summary of effects in California, and the state's response – Visit the DOC’s CGS @CalConservation @CAGeoSurvey website to learn more about the impact to #California and to stay updated over time: https://t.co/Fp42JRXYmz pic.twitter.com/ldJ7QTKeI2
Background Material
Tsunami Notifications
"If a tsunami does impact California, it is unlikely it will be a large tsunami but possibly in the Advisory range (0.3m to 1m) and it could arrive at about 0700AM Pacific time according to the NTWC." https://t.co/ioUmU0Yrd3 https://t.co/0b8aE12CV5
However, based on the latest information, there is NO TSUNAMI THREAT for American Samoa at this time.
Because this volcano remains active, please stay tuned for further updates.
Tsunami | Volcano Education
What boaters should know brochure for CA:https://t.co/OWXiUYuAhg
> Strong and unpredictable currents, especially where there are narrow entrances, narrow openings, and other narrow parts of harbor.
3. Much tsunami damage happens in ports because of the currents. Moving water has huge momentum.
[2/2]
A few sample sites for information:#EMBC: https://t.co/nbn6eGEhye
CRD #yyj: https://t.co/6yVbOlZeRD
Alberni: https://t.co/VWxLMdPtF1
Tofino: https://t.co/lvoZGmhTK8
Most important – check with, and follow the advice of your local emergency managers! pic.twitter.com/LURr5aFH3S
Tsunami Observations
USA (CA)
The first surge may not be the largest. In other locations today, the largest surge came much later than the first arrival time. In Monterey, CA it may have 2.5 feet above high-tide conditions, similar to a King Tide event. pic.twitter.com/3h7cpXiPZr
A Tsunami is occurring. Remember- the first wave may not be that largest. Move away from the shore and head to high ground. https://t.co/npoUHxEZLS pic.twitter.com/HmXl5cyIkr
(L) Sat. morning Jan 15
(R) Thurs. afternoon Jan 20 pic.twitter.com/XAAnzYK8GH
From here a resort on Tongatapu.
Don’t do what the videographer here did. This was unsafe and they are incredibly lucky.
Some videos on Youtube: Santa Cruz
Crescent City
Oregon
21 cm (.7 ft) at Newport, OR
6 cm (.2 ft) at Astoria, OR
15 cm (.5 ft) at Westport, WA
34 cm (1.1 ft) at La Push, WAPacific
El oleaje arrasó con al menos dos muelles uno que aparentemente sería de acceso público y otro privado, se mantiene alerta de tsunami en la zona.pic.twitter.com/ChYMvIM2wr
Port San Luis, CA: 4.3 ft
King Cove, AK: 3.3 ft
Crescent City, CA: 3.7 ft
Point Reyes, CA: 2.9 ft pic.twitter.com/HeZJldZlxZ
Photos: Haloti Ulufonua, FB pic.twitter.com/QndVbTYtgo
Hopefully aerial views by New Zealand Defence Force suggest #tsunami height of only few meters and limited inundation distance.
Here Nomuka island 70km NE of Hunga Tonga volcano. Google earth 2016 image follows pic.twitter.com/bUgwtsJ7f8
↙️18 Dec. 2021 ↘️17 Jan. pic.twitter.com/rtrWOXgpC4
Tsunami Modeling
Volcano Eruption | Atmospheric Observations
For more information on volcanic ash go here: https://t.co/AKigF7Zcwy
The health hazards here: https://t.co/30JBdoEpgMhttps://t.co/KSH2fr1tNR
今日15日(土)の20時から21時過ぎにかけて、日本全国で一時的な気圧変化が見られました。火山島フンガトンガ・フンガハアパイが午後に噴火した時の衝撃波が到達した可能性があります。https://t.co/p4ofQT1pC8 pic.twitter.com/yEVBFzVxCH
The spectrum shows signal at <0.06 Hz (>17 sec) & at 0.1 to 0.2 Hz (5 to 10 sec), which fits for ocean & continental Rayleigh waves.@jpulli @stevenjgibbons @KaseyAderhold pic.twitter.com/hJZJvO59PM
More important is how the people of Tonga are and is this over? We do not know. https://t.co/YiJ4vahkPu
Here is the pressure wave from the #HungaTongaHungaHaapai eruption in the infrasound section. The wave taking the path the other way around Earth is also clearly visible a few hours later.
Dashes: speed of sound#Tonga pic.twitter.com/ukkm1AXZCx
❄️cooling of the upper #troposphere by some degrees and 🔥warming the lower #stratosphere
the #tropopause pushed up by 600m in a 10°x15° area and by more then 1km locally pic.twitter.com/l1oHod0Apz
Fascinating | Sad Observations
Tsunami Webcam Network
Earthquake Report: M 8.2 near Perryville, Alaska
https://earthquake.usgs.gov/earthquakes/eventpage/us6000f02w/executive
Rick Wilson runs the tsunami program at the California Geological Survey (CGS) and works with the California Governor’s Office of Emergency Services (Cal OES) to use official forecasts of tsunami size from the National Tsunami Warning Center (NTWC) to alert coastal emergency managers about the level of potential evacuation that they may want to act upon.
More about this process can be found here. Take a look at the CGS Special Report 236 to learn about the Tsunami Playbooks and the “FASTER” approach for tsunami evacuation guidance. Evacuation is something that is done at the local level, so CGS and Cal OES can only provide recommendations.
Needless to say, we were both at the ready to respond. Rick has hourly phone calls with the NTWC and follows up with phone calls and emails to specific interested parties (e.g. the emergency managers). We each went into tsunami response mode. I manage the Tsunami Event Response Team, which may be activated to collect observations of tsunami inundation or ocean currents.
I started looking at tide gage and DART Buoy data to see how large the tsunami was in the epicentral region. The M 8.2 was in the region of the 1938 M 8.2 earthquake which generated a transoceanic tsunami. I also looked into the literature about the 1938 tsunami, to see what size that tsunami was. The 1938 tsunami had a decimeter scale wave height (peak to trough) for gages in Alaska and in California (Johnson and Satake, 1994). Jeff Freymueller et al. (2021) had also recently worked on the 1938 earthquake source area and tsunami modeling as well.
The nearest tide gage for this 2021 event is at Sand Point, but the nearest gage in 1938 was in Unalaska. So, in order to get a modest comparison between 1938 and 2021, I felt a need to wait for the Unalaska data to trickle in. This may give us some idea whether the 1938 tsunami recorded in Crescent City and San Francisco might be a decent analogue. Of course, we need to get the official forecast from the NTWC prior to sending out any information. But, that process can take hours (over 3 hours in this case). So, we need to get our minds wrangled around the possibilities in the absence of more information.
Earthquake and Tectonic Background:
The plate boundary in the north Pacific is a convergent (pushing together) plate boundary where the Pacific plate on the south ‘subducts’ northwards beneath the North America plate on the north. The Alaska-Aleutian subduction zone forms a deep sea trench which can be seen in maps of the region. The subduction zone fault dips into the Earth, getting deeper to the north.
Between earthquakes (the interseismic period), the megathrust fault is seismogenically coupled (i.e. ‘locked’) just like velcro has the ability to hold together one’s wallet. The plates are always moving towards each other. Because the fault is locked, the crust surrounding the fault bends elastically to accommodate this convergent motion.
As the crust bends and flexes, it stores energy (i.e. tectonic strain). The part of the fault closest to the seafloor (the southernmost part of this subduction zone fault) gets pulled downwards, while the part of the crust further to the north flexes upwards.
The materials along the earthquake fault have properties that resist motion (like the velcro). But, as the plates converge and increase the amount of energy stored, the forces on the fault may exceed the strength of the fault. At this time, the fault slips, causing an earthquake.
The part of the fault that was being pulled downwards gets pushed upwards during the earthquake (the coseismic period), while the crust that was being flexed upwards between earthquakes thus subsides downwards during the earthquake.
The Alaska-Aleutian subduction zone has a history of subduction zone earthquakes and tsunami, plus there exists a prehistory of earthquakes and tsunami in some parts of this plate boundary. Geologists are often asked to determine the potential hazard of future earthquakes and tsunami and their answers are based on what we know from the past (using both historic and prehistoric data).
The 2021 M 8.2 earthquake happened in the same location as a 1938 M 8.2 earthquake, just to the east of a sequence of earthquakes from last year (22 July and 19 October 2020).
Tsunami:
When the earthquake fault slips, and the upper plate deforms, the vertical motion of the plate can elevate (or lower) the overlying ocean water. After the water changes position, it seeks to return to sea-level (an equipotential surface). If elevated, the water drops downwards and then oscillates up and down. This is the process that generates waves that radiate from the area with seafloor deformed by the earthquake.
Things that make a tsunami larger are [generally]:
First of all, based on the earthquake slip models (estimates of how the earthquake slipped, in meters, and how that slip varied along the fault) suggest that a majority of the largest slip happened beneath the continental shelf. The water depth on the shelf is similar to many shelfs worldwide, shallower than about 200 meters. How does this affect the size of the tsunami?
Well, I guess that is the main point, the ground deformation that generated the tsunami was beneath shallow water.
These slip models are based on a variety of data and most of the data are seismic data. Some tsunami are generated by slow slip (not generating seismic waves) on the shallow part of the fault. These are called tsunami earthquakes.
Because tsunami earthquakes may be generated by slip in this way, slip models using seismic data cannot resolve the location of the slip on the fault that created these tsunami. However, the tsunami from this 2021 M 8.2 earthquake were small. Therefore the updip part of the fault probably did not contribute significantly to the tsunamigenic ground deformation.Below is my interpretive poster for this earthquake
I include some inset figures. Some of the same figures are located in different places on the larger scale map below. I present 3 posters, each with slightly different information.
Tectonic Overview
Youtube Source IRIS
mp4 file for downloading.
Credits:
Here is a cross section showing the differences of vertical deformation between the coseismic (during the earthquake) and interseismic (between earthquakes).
This figure, from Atwater et al. (2005) shows the earthquake deformation cycle and includes the aspect that the uplift deformation of the seafloor can cause a tsunami.
Here is a figure recently published in the 5th International Conference of IGCP 588 by the Division of Geological and Geophysical Surveys, Dept. of Natural Resources, State of Alaska (State of Alaska, 2015). This is derived from a figure published originally by Plafker (1969). There is a cross section included that shows how the slip was distributed along upper plate faults (e.g. the Patton Bay and Middleton Island faults).
Here is a graphic showing the sediment-stratigraphic evidence of earthquakes in Cascadia, but the analogy works for Alaska also. Atwater et al., 2005. There are 3 panels on the left, showing times of (1) prior to earthquake, (2) several years following the earthquake, and (3) centuries after the earthquake. Before the earthquake, the ground is sufficiently above sea level that trees can grow without fear of being inundated with salt water. During the earthquake, the ground subsides (lowers) so that the area is now inundated during high tides. The salt water kills the trees and other plants. Tidal sediment (like mud) starts to be deposited above the pre-earthquake ground surface. This sediment has organisms within it that reflect the tidal environment. Eventually, the sediment builds up and the crust deforms interseismically until the ground surface is again above sea level. Now plants that can survive in this environment start growing again. There are stumps and tree snags that were rooted in the pre-earthquake soil that can be used to estimate the age of the earthquake using radiocarbon age determinations. The tree snags form “ghost forests.
This is a photo that I took along the Seward HWY 1, that runs east of Anchorage along the Turnagain Arm. I attended the 2014 Seismological Society of America Meeting that was located in Anchorage to commemorate the anniversary of the Good Friday Earthquake. This is a ghost forest of trees that perished as a result of coseismic subsidence during the earthquake. Copyright Jason R. Patton (2014). This region subsided coseismically during the 1964 earthquake. Here are some photos from the paleoseismology field trip. (Please contact me for a higher resolution version of this image: quakejay at gmail.com)
This is another video about the 1964 Good Friday Earthquake and how we learned about what happened.
Tsunami Data
Each plot includes three datasets:
Note the all tsunami wave height plots are the same vertical scale, except for Sand Point.
I measured the largest wave heights for each site, displayed in yellow.
Alaska
Here are the data from the DART buoy nearest the M 8.2. People often mistake these data for tsunami data, but this is generated by seismic waves.
One way to test one’s hypothesis about whether these buoy data are seismic waves or tsunami waves, one simply need to take a look at the time that the wave begins to be recorded by the DART buoy.
Seismic waves travel through water at about 1.5 kms per second. While tsunami wave velocity (based on the shallow water wave equation) for depths ranging from 200-4000 meters is between ~0.02 to 0.2 kms per second, much slower than seismic waves.
Surface Deformation
North, East, and Up are positive (blue) while South, West, and Down are negative (red).
Note the upper panel and how the Pacific plate is moving to the north and the North America is moving south. Does this make sense?
The middle panel is interesting too, but skip to the lower panel, vertical. The accretionary prism (forming the continental slope), directly above the aftershocks and mainshock, rises up during the earthquake. The upper North America plate landward of the slip patch subsides. Does this make sense?
Earlier in this report we took a look at the geologic evidence for megathrust subduction zone earthquakes, evidence that records this “coseismic” subsidence.
Shaking Intensity and Potential for Ground Failure
Landslide ground shaking can change the Factor of Safety in several ways that might increase the driving force or decrease the resisting force. Keefer (1984) studied a global data set of earthquake triggered landslides and found that larger earthquakes trigger larger and more numerous landslides across a larger area than do smaller earthquakes. Earthquakes can cause landslides because the seismic waves can cause the driving force to increase (the earthquake motions can “push” the land downwards), leading to a landslide. In addition, ground shaking can change the strength of these earth materials (a form of resisting force) with a process called liquefaction.
Sediment or soil strength is based upon the ability for sediment particles to push against each other without moving. This is a combination of friction and the forces exerted between these particles. This is loosely what we call the “angle of internal friction.” Liquefaction is a process by which pore pressure increases cause water to push out against the sediment particles so that they are no longer touching.
An analogy that some may be familiar with relates to a visit to the beach. When one is walking on the wet sand near the shoreline, the sand may hold the weight of our body generally pretty well. However, if we stop and vibrate our feet back and forth, this causes pore pressure to increase and we sink into the sand as the sand liquefies. Or, at least our feet sink into the sand.
Below is a diagram showing how an increase in pore pressure can push against the sediment particles so that they are not touching any more. This allows the particles to move around and this is why our feet sink in the sand in the analogy above. This is also what changes the strength of earth materials such that a landslide can be triggered.
Below is a diagram based upon a publication designed to educate the public about landslides and the processes that trigger them (USGS, 2004). Additional background information about landslide types can be found in Highland et al. (2008). There was a variety of landslide types that can be observed surrounding the earthquake region. So, this illustration can help people when they observing the landscape response to the earthquake whether they are using aerial imagery, photos in newspaper or website articles, or videos on social media. Will you be able to locate a landslide scarp or the toe of a landslide? This figure shows a rotational landslide, one where the land rotates along a curvilinear failure surface.
Some Relevant Discussion and Figures
Fig. 1). Dotted horizontal lines show our correlation of evidence for some younger earthquakes and tsunamis. Times of great earthquakes inferred from episodes of village abandonment determined from archaeological stratigraphy in the eastern Alaska-Aleutian megathrust region are also shown (Hutchinson and Crowell, 2007).
Alaska | Kamchatka | Kurile
General Overview
Earthquake Reports
Social Media
BREAKING: Tsunami sirens sound in Kodiak, Alaska after a major magnitude 8.2 earthquake struck off the coast; risk being evaluated for the Pacific pic.twitter.com/amxpLGX70s
tectonic background:https://t.co/L4RHgNdex7 pic.twitter.com/uQ2ur85EaC
My initial guess that today's event may have been similar to the 1938 M8.2 earthquake still looks like it has some merit.
Follow https://t.co/A1MNRg1WKF for updates on tsunami warnings. pic.twitter.com/g4qME2w0SI
tsunami prehistory and history for region doi:10.1130/GES01108.1https://t.co/mFtEoigFQB
more background here https://t.co/L4RHgNdex7 pic.twitter.com/HXpQUVSWFE
B/c most of elastic energy was released deeper in the Earth.
Stations near Denali NP ~900 km moved a few mm… See https://t.co/4zpOW4m1pJ for more info and data. pic.twitter.com/j1GSIazVfJ
tectonic background here:https://t.co/L4RHgNdex7 pic.twitter.com/iTMmm5u2LQ
References:
Basic & General References
Specific References
Return to the Earthquake Reports page.
Earthquake Report: Tōhoku-oki Earthquake Ten Years Later
There are numerous web experiences focused on this type of reflection. Here is a short list, some of which I have been involved in.
Updated Interpretive Poster
I include some inset figures.
Seismicity
Web Map
Earthquake Intensity
Web Map
Tsunami
We think that the earthquake slipped at least 50 meters (165 feet) during several minutes. This is the largest coseismic measurement of any subduction zone earthquake (so far).
When the fault slipped, it caused the seafloor to deform and move. This motion also displaced the overlying water column.
As the water column is elevated, it gains potential energy. As this uplifted water expends this energy by oscillating up and down, it radiates energy in the form of tsunami waves.
Tsunami were observed across the entire Pacific Basin, causing extensive damage and casualties in Japan, but also in other places too. There was about $100 million damage to coastal infrastructure in California alone.
This is an animated model of the Great East Japan tsunami of ten years ago. The warmer the colors, the larger the wave. The first surges reached the closest Japan coasts in about 25 minutes. The first surges reached Crescent City in 9.5 hours. (modified text from Dr. Lori Dengler)
This is the same map used as an overlay in the web map below.
Here is the tide gage record from Crescent City, California, USA.
Time is represented by the horizontal axis and elevation is represented on the vertical axis. The darker blue line in this image represents NOAA’s tidal forecast. The data recorded by the tide gage are represented by the light blue colored lines. Wave height is the distance measured between the wave crest and trough. Wave amplitude is the level of water above sea level.
Some of these data came from the IOC sea level monitoring website.
Web Map
There is an overlay of color that represents the size of the tsunami as it travelled across the ocean. Learn more about these data here.
Ground Failure
Landslide ground shaking can change the Factor of Safety in several ways that might increase the driving force or decrease the resisting force. Keefer (1984) studied a global data set of earthquake triggered landslides and found that larger earthquakes trigger larger and more numerous landslides across a larger area than do smaller earthquakes. Earthquakes can cause landslides because the seismic waves can cause the driving force to increase (the earthquake motions can “push” the land downwards), leading to a landslide. In addition, ground shaking can change the strength of these earth materials (a form of resisting force) with a process called liquefaction.
Sediment or soil strength is based upon the ability for sediment particles to push against each other without moving. This is a combination of friction and the forces exerted between these particles. This is loosely what we call the “angle of internal friction.” Liquefaction is a process by which pore pressure increases cause water to push out against the sediment particles so that they are no longer touching.
An analogy that some may be familiar with relates to a visit to the beach. When one is walking on the wet sand near the shoreline, the sand may hold the weight of our body generally pretty well. However, if we stop and vibrate our feet back and forth, this causes pore pressure to increase and we sink into the sand as the sand liquefies. Or, at least our feet sink into the sand.
Below is a diagram showing how an increase in pore pressure can push against the sediment particles so that they are not touching any more. This allows the particles to move around and this is why our feet sink in the sand in the analogy above. This is also what changes the strength of earth materials such that a landslide can be triggered.
Below is a diagram based upon a publication designed to educate the public about landslides and the processes that trigger them (USGS, 2004). Additional background information about landslide types can be found in Highland et al. (2008). There was a variety of landslide types that can be observed surrounding the earthquake region. So, this illustration can help people when they observing the landscape response to the earthquake whether they are using aerial imagery, photos in newspaper or website articles, or videos on social media. Will you be able to locate a landslide scarp or the toe of a landslide? This figure shows a rotational landslide, one where the land rotates along a curvilinear failure surface.
Use this map to see the magnitudes of different earthquakes experienced in Japan. The map shows earthquake epicenters for large-magnitude historic events of the past century. It also includes epicenters for all aftershocks and triggered earthquakes for a year after the M 9.1 earthquake, and an outline of the aftershocks, which illustrates the area of the fault that slipped during the M9.1 earthquake.
Web Map
Japan | Izu-Bonin | Mariana
General Overview
Earthquake Reports
Social Media
check out the tide gage plots, about 50 of them
References:
Basic & General References
Specific References
Return to the Earthquake Reports page.
Earthquake Report (and Tsunami) Oaxaca, Mexico
The M 7.4 Oaxaca, Mexico Earthquake occurred along the megathrust fault interface (an “interplate” earthquake) based on our knowledge of the location of the fault, our calculation of the earthquake location, and the earthquake mechanisms prepared by seismologists (i.e. focal mechanisms or moment tensors).
I noticed that there is a down-first wave prior to the tsunami. This was observed at both stations (Acapulco and Salina Cruz). Dr. Costas Synolakis (USC) informed me that this is a well known phenomena called a “Leading Depression N-wave.” I mark the location of the Salina Cruz gage on the interpretive poster below.Below is my interpretive poster for this earthquake
I include some inset figures. Some of the same figures are located in different places on the larger scale map below.
Other Report Pages
Some Relevant Discussion and Figures
Earthquake Triggered Landslides
Mexico | Central America
General Overview
Earthquake Reports
Social Media
Calculated with @antandre71 pic.twitter.com/6hQFMV55EX
CERRADA LA CARRETERA OAXACA-ISTMO POR #Sismo 7.5
Waiting #sentinel1…
Surface projection of the slip distribution by @USGS superimposed on the quickly forward model on #ArcGis platform; white lines indicate #Slab2 depth boundaries. The seismogenic fault is also shown in 3D view map (magenta plain). pic.twitter.com/sm62EHfF8Z
This one below is a recording from SE England pic.twitter.com/6RRzPsHAGK
References:
Basic & General References
Specific References
Return to the Earthquake Reports page.
Earthquake Report: Gorda Rise
On 18 May 2020 there was a magnitude M 5.5 extensional earthquake located near the Gorda Rise, an oceanic spreading ridge where oceanic crust is formed to create (love using the word create in science) the Gorda and Pacific plates.
https://earthquake.usgs.gov/earthquakes/eventpage/us70009jgy/executive
There are three types of plate boundaries and three types of earthquake faults (this is not a coincidence because plate boundaries are generally in the form of earthquake faults).
The northeast Pacific (aka Pacific Northwest as viewed by land lubbers) is dominated by the plate boundary formed between the Pacific (PP) and North America plates (NAP). In much of California, this plate boundary is realized in the form of the San Andreas fault (SAF), where the PP moves north relative to the NAP. Both plates are moving to the northwest, but the PP is moving faster, so it appears that the NAP is moving south. This southerly motion is relative not absolute. I present a background of the SAF in my review of the 1906 San Francisco earthquake here.
Near Cape Mendocino, in Humboldt County, California, the plate boundary gets more complicated and involves all three types of fault systems.
It appears that the San Andreas fault terminates in the King Range, causing some of the highest tectonic uplift rates in North America. There are sibling faults to the east of the San Andreas that continue further north (e.g. the Maacama fault turns into the Garberville fault and the Bartlett Springs fault (eventually) turns into the Bald Mountain/Big Lagoon fault. So, it looks like these San Andreas related faults extend offshore, possibly to at least the Oregon border. Geodetic evidence supports this, as first published by Williams et al. (2002).
The San Andreas ends near the beginning of the Cascadia subduction zone (CSZ), formed where the Gorda/Juan de Fuca/Explorer plates dive eastwards beneath the North America plate. More about the CSZ can be found here, where I describe the basis of our knowledge about prehistoric earthquakes and tsunami along the CSZ.
Far offshore of the CSZ are oceanic spreading ridges, the Gorda Rise and the Juan de Fuca Ridge. Because the plates are moving away from each other here (we think this is due to processes called slab pull and ridge push; slab pull describes the process that in the subduction zone, the downgoing oceanic plate is going deep into the mantle and pulling down the crust; ridge push is not really pushing from the ridge, but that there is additional mass added to the crust and this pushes down and then out, pushing the plate away from the ridge, towards the subduction zone). As these plates diverge, there is lowered pressure beneath this divergent zone. These lowered pressures cause the mantle to melt, leading to eruptions of mafic lava. When the lava cools, it becomes new oceanic crust.
Connecting the CSZ with these spreading ridges, and spreading ridges with other spreading ridges, are transform plate boundaries in the form of strike-slip faults. For example, the Mendocino fault and the Blanco fault. Here is a report that includes background information about the Mendocino fault. Here is a report with some background information about the Blamco fault.
The 18 May 2020 M 5.5 earthquake happened near the Gorda Rise and was an extensional earthquake. As the Gorda plate moves away from the spreading ridge, the normal faults formed at the ridge don’t disappear. The Gorda plate is a strange plate as it gets internally deformed, so as the plate moves towards the subduction zone, these normal faults get reactivated as strike-slip faults. These strike-slip faults have been responsible for some of the most damaging earthquakes to impact coastal northern California. More about these left-lateral strike-slip Gorda plate earthquakes can be found in a report here.
The M 5.5 earthquake happened along one of these normal faults, before that fault turns into a strike-slip fault. There is a good history of earthquakes just like this one. Here is a report for a similar event further to the north, also slightly east of the Gorda Rise.
One of the most common questions people have is, “does this earthquake change our chances for a CSZ earthquake?” The answer is no. The reason is because the stress changes from earthquakes extends for a limited distance from those earthquakes. I spend more time discussing this limitation for the Blanco fault here. Basically, this M 5.5 event was too small and too far away from the CSZ to change the chance that the CSZ will slip. Today is not different from a couple weeks ago: we always need to be ready for an earthquake when we live in earthquake country.Below is my interpretive poster for this earthquake
I include some inset figures. Some of the same figures are located in different places on the larger scale map below.
Other Report Pages
Some Relevant Discussion and Figures
I have compiled some literature about the CSZ earthquake and tsunami. Here is a short list that might help us learn about what is contained within the core that I collected.
There have been several series of intra-plate earthquakes in the Gorda plate. Two main shocks that I plot of this type of earthquake are the 1980 (Mw 7.2) and 2005 (Mw 7.2) earthquakes. I place orange lines approximately where the faults are that ruptured in 1980 and 2005. These are also plotted in the Rollins and Stein (2010) figure above. The Gorda plate is being deformed due to compression between the Pacific plate to the south and the Juan de Fuca plate to the north. Due to this north-south compression, the plate is deforming internally so that normal faults that formed at the spreading center (the Gorda Rise) are reactivated as left-lateral strike-slip faults. In 2014, there was another swarm of left-lateral earthquakes in the Gorda plate. I posted some material about the Gorda plate setting on this page.
Cascadia subduction zone
General Overview
Earthquake Reports
Gorda plate
Blanco transform fault
Mendocino fault
Mendocino triple junction
North America plate
Explorer plate
Uncertain
Social Media
References:
Basic & General References
Specific References
Return to the Earthquake Reports page.
Earthquake Report: Mendocino triple junction
In the past 9 months it was also a big mag 5 MTJ year. There have been 3 mag 5+ earthquakes in the Mendocino triple junction (MTJ) region. The first one in June of 2019, at the time, appeared to be related to the Mendocino fault. The 9 March M 5.8 event was clearly associated with the right lateral Mendocino transform fault. The latest in this series of unrelated earthquakes is possibly associated with NW striking faults in the Gorda plate. I will discuss this below and include background about all the different faults in the region.
My social media feed was immediately dominated by posts about the earthquake in Humboldt County. I put together a quick map (see below). My good friend and collaborator Bob McPherson (a seismologist who ran the Humboldt Bay Seismic Network in the late 70s and 80s) sent me several text messages about the earthquake. we texted back and forth. I initially thought it might be Mendo fault and so did he.
Then the USGS moment tensor (earthquake mechanism) came in with an orientation similar to that of Gorda plate earthquakes further to the north. These earthquakes are typically on northeast striking (trending) left-lateral strike-slip faults (see more here about types of earthquakes). So, I stated that I thought it was like those, a left-lateral strike-slip fault earthquake. So I deleted my social media posts and updated the map to show it could be either left-lateral or right-lateral (the map below shows both options), but that we thought it was in the Gorda plate, not the Mendocino fault.
Then Bomac mentioned these northwest trends in seismicity that we noticed (as a group) about 5 years ago, seismicity trends (seismolineaments is what Tom calls them) that first appeared following the 1992 Cape Mendocino Earthquake.
We don’t yet have a full explanation for these trends in seismicity, but the orientation fits a stress field from north-south compression (from the northward motion of the Pacific plate relative to the Gorda plate). This north-south compression is also the explanation for the left-lateral strike-slip fault earthquakes in the Gorda plate (Silver, 1971).How are these 3 M5+ MTJ events related?
WHy?
Well, there are two kinds of earthquake triggering.
* note, i corrected this caption by changing the word “relationships” to “relations.”
The M 5.6 might have a rupture length crudely about 3 km might affect the region up to 9 km away. The M 5.2 is ~16 km from the M 5.6, so probably too far to be affected.
However, these earthquakes are related because they are all in the same region and are responding to the same tectonic forces.Below is my interpretive poster for this earthquake
I include some inset figures. Some of the same figures are located in different places on the larger scale map below.
There is a nice northeast trend in seismicity that I also outlined. This is probably representative of one of the typical left-lateral Strike-slip Gorda plate earthquakes.Other Report Pages
Some Relevant Discussion and Figures
I have compiled some literature about the CSZ earthquake and tsunami. Here is a short list that might help us learn about what is contained within the core that I collected.
These two quakes appear to be aligned with the two northwest trends in seismicity and the 18 March 2020 M 5.2. The orientation of the mechanisms are not as perfectly well aligned, but there are lots of reasons for this (perhaps the faults were formed in a slightly different orientation, but have rotated slightly).
There have been several series of intra-plate earthquakes in the Gorda plate. Two main shocks that I plot of this type of earthquake are the 1980 (Mw 7.2) and 2005 (Mw 7.2) earthquakes. I place orange lines approximately where the faults are that ruptured in 1980 and 2005. These are also plotted in the Rollins and Stein (2010) figure above. The Gorda plate is being deformed due to compression between the Pacific plate to the south and the Juan de Fuca plate to the north. Due to this north-south compression, the plate is deforming internally so that normal faults that formed at the spreading center (the Gorda Rise) are reactivated as left-lateral strike-slip faults. In 2014, there was another swarm of left-lateral earthquakes in the Gorda plate. I posted some material about the Gorda plate setting on this page.
Further North
If we turn our head at an oblique angle, we may consider the San Andreas, the Mendocino, and the Blanco faults to be all part of the same transform fault.
Transform faults are often (or solely) defined as a strike-slip fault system that terminates at each end with a spreading ridge. These 3 systems link spreading ridges in the Gulf of California, through the Gorda Rise, to the Juan de Fuca ridge (and further).
The Blanco fault is as, or more active than the Mendocino fault. The excellent people in Oregon who are aware of their exposure to seismic and tsunami hazards from the Cascadia subduction zone are always interested when there are earthquake notifications.
Earthquakes on the Blanco fault are some of these events that people notice and ask about, “should I be concerned?” The answer is generally, “those earthquakes are too far away and too small to change the chance of the “Big One.” (remember the discussion about dynamic triggering above?)
There was a recent earthquake (2018) on the Blanco fault that brought the public to question this again. My report about that earthquake spent a little space addressing these fault length >> magnitude >> triggering issues.
As we know, the tectonics of the northeast Pacific is dominated by the Cascadia subduction zone, a convergent plate boundary, where the Explorer, Juan de Fuca, and Gorda oceanic plates dive eastward beneath the North America plate.
These oceanic plates are created (formed, though I love writing “created” in science writing) at oceanic spreading ridges/centers.
When oceanic spreading centers are offset laterally, a strike-slip fault forms called a transform fault. The Blanco transform fault is a right-lateral strike-slip fault (like the San Andreas fault). Thanks to Dr. Harold Tobin for pointing out why this is not a fracture zone.
The main take away is that we are not at a greater risk because of these earthquakes.
Cascadia subduction zone
General Overview
Earthquake Reports
Gorda plate
Blanco transform fault
Mendocino fault
Mendocino triple junction
North America plate
Explorer plate
Uncertain
Social Media
References:
Basic & General References
Specific References
Return to the Earthquake Reports page.
Earthquake Report: Salt Lake City
https://earthquake.usgs.gov/earthquakes/eventpage/uu60363602/executive
The second thing I thought of was Chris DuRoss, a USGS geologist I first met when he was presenting his research of the record of prehistoric earthquakes along the Wasatch fault at the Seismological Society of America (SSA) meeting that was being held in SLC that year. Gosh, that was in 2013. My, how time passes. Dr. DuRoss now works for the USGS and continues to research the seismic hazards of the intermountain west and beyond from his office in Golden, Colorado.
The third thing I thought of was all the buildings in the SLC area that are not designed to withstand the shaking from the earthquakes that we expect will occur on that fault system. About 85% of the population of the state of Utah lives within 15 miles of the Wasatch fault. This is sobering.
I quickly put together a poster for this earthquake to help people learn a little more. I have a second earthquake to interpret tonight, so I will update this report later with more background on the Wasatch fault tectonics and seismic hazard.
There is also a great resource from the University of Utah, an event page for this earthquake sequence.Tectonic Background
There are “sibling” faults to the SAF near the SAF (like the Hayward fault in the San Francisco Bay Area) and further away (like the Eastern California shear zone, the Owens Valley fault, and the Walker Lane fault systems).
Just like Dr. Steve Wesnousky showed us, the crust in the Walker Lane is moving around like a layer of solid wax floating around on a tray of melted wax. So, there are faults in lots of different kinds of directions, and different kinds of faults too.
The easternmost right-lateral strike slip fault is the Wasatch fault.
East of Sierra Nevada. in Nevada and western Utah, there is lots of East-West oriented extension (i.e. the Basin and Range) where the crust in western Nevada is moving west compared to the crust in Salt Lake City, Utah.
The Wasatch is also one of these extensional faults we call Normal faults.
In Salt Lake City, the Wasatch fault is oriented roughly north-south and is generally located on the eastern side of the valley, near the base of the mountains. The Crust on the western side of the fault is moving west relative to the mountains.
The fault then dips down towards the west. Because the motion is east-west, and the fault dips at an angle, the valley goes down over time relative to the mountains (thus forming the valley).
Today’s earthquake happened in the middle of the valley, where the Wasatch fault is deep beneath. The earthquake was a “normal” fault earthquake with east-west extension. So, the earthquake and aftershocks are on a fault related to the Wasatch (or we are wrong about the precise location of the fault, the earthquake, or both).
The USGS has an earthquake forecast product where the scientists at the Earthquake Center use a statistical model to estimate the possibility of earthquakes of different magnitude ranges may occur in the future over ranges of time periods after the main earthquake.
Don’t run outside during an earthquake.
Below is my interpretive poster for this earthquake
I include some inset figures. Some of the same figures are located in different places on the larger scale map below.
Other Report Pages
Some Relevant Discussion and Figures
Earthquake Triggered Landslides
There are many different ways in which a landslide can be triggered. The first order relations behind slope failure (landslides) is that the “resisting” forces that are preventing slope failure (e.g. the strength of the bedrock or soil) are overcome by the “driving” forces that are pushing this land downwards (e.g. gravity). The ratio of resisting forces to driving forces is called the Factor of Safety (FOS). We can write this ratio like this:
Landslide ground shaking can change the Factor of Safety in several ways that might increase the driving force or decrease the resisting force. Keefer (1984) studied a global data set of earthquake triggered landslides and found that larger earthquakes trigger larger and more numerous landslides across a larger area than do smaller earthquakes. Earthquakes can cause landslides because the seismic waves can cause the driving force to increase (the earthquake motions can “push” the land downwards), leading to a landslide. In addition, ground shaking can change the strength of these earth materials (a form of resisting force) with a process called liquefaction.
Sediment or soil strength is based upon the ability for sediment particles to push against each other without moving. This is a combination of friction and the forces exerted between these particles. This is loosely what we call the “angle of internal friction.” Liquefaction is a process by which pore pressure increases cause water to push out against the sediment particles so that they are no longer touching.
An analogy that some may be familiar with relates to a visit to the beach. When one is walking on the wet sand near the shoreline, the sand may hold the weight of our body generally pretty well. However, if we stop and vibrate our feet back and forth, this causes pore pressure to increase and we sink into the sand as the sand liquefies. Or, at least our feet sink into the sand.
Below is a diagram showing how an increase in pore pressure can push against the sediment particles so that they are not touching any more. This allows the particles to move around and this is why our feet sink in the sand in the analogy above. This is also what changes the strength of earth materials such that a landslide can be triggered.
Below is a diagram based upon a publication designed to educate the public about landslides and the processes that trigger them (USGS, 2004). Additional background information about landslide types can be found in Highland et al. (2008). There was a variety of landslide types that can be observed surrounding the earthquake region. So, this illustration can help people when they observing the landscape response to the earthquake whether they are using aerial imagery, photos in newspaper or website articles, or videos on social media. Will you be able to locate a landslide scarp or the toe of a landslide? This figure shows a rotational landslide, one where the land rotates along a curvilinear failure surface.
Basin and Range
General Overview
Earthquake Reports
Utah
Idaho
Nevada
Social Media
References:
Basic & General References
Specific References
Return to the Earthquake Reports page.
Earthquake Report: Mendocino fault
As I was grabbing a bite at Taqueria Bravo in Willits, I checked in on social media and noticed my friend Dave Bazard had posted moments earlier about an earthquake there. I had missed it by about 2 hours or so.
https://earthquake.usgs.gov/earthquakes/eventpage/nc73351710/executive
Yesterday’s earthquake was a right-lateral strike-slip earthquake on the Mendocino fault system. The Mendocino fault is a strike-slip fault formed by the eastward motion of the Gorda plate relative to the westward motion of the Pacific plate. The last major damaging earthquake on the MF was in 1994.
Interestingly, this was the 6 year commemoration of the 2014 M 6.8 Gorda plate earthquake (the last large earthquake in the region).
Also, there was a similarly sized event on the MF in 2018.
Big “take-aways” from this:
Below is my interpretive poster for this earthquake
I include some inset figures. Some of the same figures are located in different places on the larger scale map below.
Other Report Pages
Some Relevant Discussion and Figures
I have compiled some literature about the CSZ earthquake and tsunami. Here is a short list that might help us learn about what is contained within the core that I collected.
Cascadia subduction zone Earthquake Reports
General Overview
Earthquake Reports
Gorda plate
Blanco transform fault
Mendocino fault
Mendocino triple junction
North America plate
Explorer plate
Uncertain
Social Media
References:
Basic & General References
Specific References
Return to the Earthquake Reports page.