Contrary to what some people spread around on the internets (some of them major earthquake experts), strike-slip earthquakes can and do generate tsunami (just like this one). More on this below.
I am in Portland, Oregon this week, attending the Winter National Tsunami Hazard Mitigation Program Meeting. While one of our workshops, several of us got an alert about a M 7.3 earthquake offshore of Cuba and Jamaica. My colleagues from Puerto Rico were immediately interested to learn more about this. We noticed that nothing was being posted to tsunami.gov.
https://earthquake.usgs.gov/earthquakes/eventpage/us60007idc/executive
The location is familiar with me as I have written reports for earthquakes in this region over the past couple of years. This earthquake happened along a strike-slip plate boundary fault. Thus, the chance of a large tsunami is low. However, strike-slip earthquakes DO generate tsunami, albeit smaller than those created by subduction zone earthquakes. In addition, earthquakes can trigger submarine landslides, which can also serve to cause tsunami (these can be very large, but generally impact the area near the landslide, like the 1998 Papua New Guinea tsunami.).
In a few minutes, the earthquake magnitude was updated to M 7.7. This is quite common, as seismological data are analyzed with greater detail after the initial automatic magnitude calculation.
A few minutes later, the USGS moment tensor (earthquake mechanism) was posted online, confirming that it was a strike-slip earthquake.
The IOC tide gage network was not working, so I could not check for tsunami observations until later. However, the Pacific Tsunami Warning Center sent out an email to the International Tsunami Bulletin Board (email list restricted to tsunami scientists) with arrival times. There was a suggestion that tsunami waves up to 1 meter may arrive along the coast in the region.
At lunch time, I went to my hotel room to put together an interpretive poster (thanks boss!) to send out on social media. By that time, a small tsunami wave had been observed at the tide gage on the west coast of Cayman Island. The PTWC sent out their final email, stating a 0.4 foot tsunami was recorded there. I went to the IOC website and the gage data were quite noisy, but it matched the PTWC email. Here is a link to the George Town Tide Gage.
Just as I was about to tweet the poster, the USGS earthquake fault slip model was published online (so I added that to the poster).
After lunch, as the workshop continued, there was a M 6.1 earthquake. I noticed it was west of the slip model. I had considered an alternate hypothesis (that the M 6.1 was triggered, not an aftershock), but now think that this is just part of the M 7.7 slip patch. Looking at the back projection data from IRIS, it suggests that this earthquake initiated in the east and propagated to the west. It makes sense to me that the fault reached a zone where the fault slip slowed down, until it reached the patch that slipped during the M 6.1. (simplifying this for this report)
Was this Cayman Islands Earthquake Sequence related to the ongoing Puerto Rico Earthquake Sequence? Probably not. They are simply too far from each other.
There are two types of earthquake triggering: static and dynamic. Triggering happens when an earthquake on one fault changes the stress on a different fault, causing that other fault to slip during an earthquake. These stress changes are small, so the “receiver” fault needs to be at a state of stress that is high enough that it would be almost ready to slip before the “source” earthquake.
Dynamic triggering happens when seismic waves from the source earthquake travel through the Earth, triggering an earthquake on the receiver fault. These changes in stress may take a while before the triggered earthquake happens, but generally, we think that this would happen while these waves are traveling through the area.
Static triggering happens when a source earthquake changes the stress in the crust surrounding the source earthquake. This change typically lasts months to years and won’t extend beyond two fault lengths of the source earthquake. So, If the source quake had a rupture length of 50 km, static triggering probably would not happen more than 100km from the source quake. This is just a rule of thumb… BUT the M 7.7 is very far from Puerto Rico, so is probably unrelated to the Puerto Rico Sequence.
Earthquake Description
This M 7.7 earthquake happened along the Oriente fault, which is the Septentrional fault further to the east. This fault is one of the boundaries between the North America plate to the north and the Caribbean plate to the south in a region called the Greater Antilles.
Further to the east, this plate boundary changes into a subduction zone along the Lesser Antilles. This subduction zone is the source of a great amount of research. There is some evidence that the megathrust subduction zone fault is not locked, so it is slipping and not capable of generating Great (M>8) earthquakes. However, I was on a team of French geologists aboard the Pourquoi Pas? in 2016. We were coring the deep sea to investigate the sedimentary record of Great earthquakes. Based on our analysis, it appears that the fault is capable of producing these large earthquakes, but the average time between earthquakes (the recurrence interval) is on he order of several millenia.
To the west of the M 7.7 earthquake, there is an oceanic spreading ridge where crust is created, forming the Cayman Trough. As the boundary steps to the south, the relative plate motion is focused on another left-lateral strike-slip fault, the Swan Island fault. This fault extends further to the west into Central America and turns into the Motagua Polochic fault system (there are actually multiple faults hypothesized to be the active part of this plate boundary here). I discuss this more in an Earthquake Report here.
Below is my interpretive poster for this earthquake
- I plot the seismicity from the past 3 months, with diameter representing magnitude (see legend). I include earthquake epicenters from 1920-2020 with magnitudes M ≥ 6.0 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.
- Some basic fundamentals of earthquake geology and plate tectonics can be found on the Earthquake Plate Tectonic Fundamentals page.
- In the lower right corner is a map from Pindell and Kennan (2009) that shows the major plate tectonic faults in the Caribbean. I place a yellow star in the general location of today’s M 7.7 earthquake.
- In the upper right corner is a map from Symithe et al. (2015). I have used this figure in many of my reports because it is so awesome!!! This map includes the faults of the region, but also includes earthquake mechanisms (e.g. focal mechanisms).
- To the left of the Symithe map is the USGS model for the earthquake fault that slipped during this earthquake. The color represents the amount of slip. I placed a red line with circles at the end on the map where this fault model is located. Don’t forget, this is just a model (but it matches the data that the USGS uses to constrain the model).
- In the upper left corner is a map that shows a comparison of the USGS model for shaking intensity (using the Modified Mercalli Intensity (MMI) scale) and the USGS “Did You Feel It?” observations.
- The shaking intensity model is based on the results of analyzing thousands of earthquakes and using these earthquakes to develop a relation between earthquake size (e.g. magnitude) and how strongly it shakes based on the distance to the earthquake.
- The “DYFI” observations are based on the results of surveys that people submit to the USGS website. The questions people answer are about their observations of the earthquake. Here are some basic facts about this DYFI program and here is some scientific background behind the DYFI program.
- To the right of the intensity map is a plot of the data from the map. The vertical axis represents intensity (MMI) and the horizontal axis represents the distance from the earthquake. The solid lines represent the model results from the USGS. These are the models that the USGS used to create the color on the map to the left. The DYFI observations are the blue dots (the brown dots show averages ofthe blue dots). There is a decent match, but it is far from perfect.
I include some inset figures. Some of the same figures are located in different places on the larger scale map below.
- Here is the tsunami observation posted by the PTWC. A few years ago, it was conventional wisdom (at least, in my mind) that strike-slip earthquakes were not a producer of tsunami. In the past few years, however, most every large strike-slip submarine earthquake has generated a tsunami. We need to break this old way of viewing this.
- The main difference for tsunami from strike-slip earthquakes is that they are smaller than from subduction or thrust faults. BUT, even a tsunami with a size of about 2-3 meters can cause millions of dollars of damage. These are still dangerous events, even though they are not as dangerous as larger tsunami.
- As we can see from the plot below, it will take someone more skilled than I to understand the tsunami waves observed here. However, even I can see that there was a change in water surface elevation at about the right time given the distance to the earthquake from the Cayman Islands.
- UPDATE: 2020.01.29 – This morning I saw a tweet from Christoph Gruetzner and I realized that I had only reviewed the tide gage data from nearest the quake. Below is a plot from a site in Mexico which clearly shows a tsunami wave train. This is a better record that the one above from Cayman Island. The Cayman gage is located on the western side of the island, not optimal to record waves sourced from the east (why it is so noisy). This Puerto Morelos gage (below) is a much better record, albeit still a small wave that is in a location with significant background wave “noise.”
- Here is a figure that includes a map showing the location of these two tide gages. I will update this later, gotta get to the meeting today.
Some Relevant Discussion and Figures
- Here is the tectonic map from Symithe et al. (2015). I include their figure caption below in blockquote.
Seismotectonic setting of the Caribbean region. Black lines show the major active plate boundary faults. Colored circles are precisely relocated seismicity [1960–2008, Engdahl et al., 1998] color coded as a function of depth. Earthquake focal mechanism are from the Global CMT Catalog (1976–2014) [Ekstrom et al., 2012], thrust focal mechanisms are shown in blue, others in red. H = Haiti, DR = Dominican Republic, MCS = mid-Cayman spreading center, WP = Windward Passage, EPGF = Enriquillo Plaintain Garden fault.
- Here is the tectonic map from Garcia-Casco et al. (2011). I include their figure caption below in blockquote.
Plate tectonic configuration of the Caribbean region showing the location of the study cases presented in this issue (numbers refer to papers, arranged as in the issue), and other important geological features of the region (compiled from several sources).
- Here is the map from Mann et a. (1991). Note how today’s earthquake is in an area that may have overlapping faults of different types.
A. Tectonic map of Cayman trough region showing strike-slip faults (heavy lines), oceanic crust (gray) in Cayman trough, and magnetic anomaly identifications (numbered bars) (after Rosencrantz et a., 1988). Arrows show relative displacement directions. Fault zones: OFZ – Oriente; DFZ- Dunvale; EPGFZ – Enriquillo-Plantain Garden; WFZ – Walton; SIFZ – Swan Islands; MFZ – Motagua. Bl. Late Miocene reconstruction of Cayman trough. C. Early Miocene reconstruction.
- Here is the large scale map from ten Brink et al. (2002) showing the bathymetry surrounding the Mid-Cayman Rise.
Bathymetry of central Cayman Trough adapted from Jacobs et al. (1989). Contour interval: 250 m. Dotted line: location of gravity transect.
- Here is the USGS Tectonic Summary for this 2018.01.10 M 7.6 earthquake. A more comprehensive review can be found here.
- The January 10, 2018, M 7.6 Great Swan Island, Honduras earthquake occurred as the result of strike slip faulting in the shallow crust near the boundary between the North America and Caribbean plates. Early focal mechanism solutions indicate that rupture occurred on a steeply dipping structure striking either west-northwest (right-lateral), or west-southwest (left-lateral). At the location of this earthquake, the North America plate moves to the west-southwest with respect to the Caribbean plate at a rate of approximately 19 mm/yr. Local to the January 10, 2018 earthquake, this motion is predominantly accommodated along the Swan Islands transform fault, a left-lateral structure. The location, depth and focal mechanism solution of today’s earthquake are consistent with rupture occurring along this plate boundary structure, or on a nearby and closely related fault.
- While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Strike-slip-faulting events of the size of the January 10, 2018, earthquake are typically about 140×20 km (length x width).
- Nine other earthquakes of M 6 or larger have occurred within 400 km of the January 10, 2018 event over the preceding century. Previous strong earthquakes along the North America-Caribbean plate boundary in this region include the destructive M 7.5 Guatemala earthquake of February 4, 1976, which resulted in more than 23,000 fatalities. The 1976 earthquake occurred on the Motagua fault, a segment of the plate boundary that lies in southern Guatemala, about 650 km west-southwest of the hypocenter of the January 10, 2018, event. In May 2009, a M 7.3 earthquake occurred along the Swan Island transform fault approximately 300 km west of the January 10, 2018 event. The 2009 earthquake (which was much closer to land than the 2018 event) resulted in 7 fatalities, 40 injuries and 130 buildings being damaged or destroyed.
- 2016.01.17 1900-2016 Summary northern Caribbean
- 2020.01.28 M 7.7 Cayman Islands
- 2020.01.07 M 6.4 Puerto Rico
- 2018.08.21 M 7.3 Venezuela
- 2018.01.10 M 7.6 Cayman Trough
- 2016.01.17 M 5.1 pair Cuba
- 2010.01.12 M 7.0 Haiti
Caribbean Earthquake Reports
General Overview
Earthquake Reports
Social Media
#EarthquakeReport for the M7.7 left-lateral strike-slip #Earthquake #Terremoto #TremblementDeTerre along the Oriente-Septentrional fault system in the #GreaterAntilles
affecting #Cuba #CaymanIslands #Jamaica #tsunami observed and #GroundShaking
report:https://t.co/8sTAMIQlq6 pic.twitter.com/Y2PCHHxuDj
— Jason "Jay" R. Patton (@patton_cascadia) January 29, 2020
Watch the M7.7 Caribbean earthquake waves roll across the USArray Transportable Array seismic network (https://t.co/RIcNz4bgWq )! #earthquake #JamaicaEarthquake pic.twitter.com/aVSu6B1DTw
— IRIS Earthquake Sci (@IRIS_EPO) January 29, 2020
7.7 magnitude earthquake 80 miles ESE of Cayman Brac & Little Cayman#earthquake video is damage from Grand Cayman in the George Town Hospital staff parking lot @lookner pic.twitter.com/AWe3MtFUUB
— Raymond Gayle (@Kentsville) January 28, 2020
S-Waves arrive after P-Waves — RIP Beer but a good lesson in earthquake physics. https://t.co/YneCbBEwQd
— Switzer Coastal lab (@CoastalLabNTU) January 29, 2020
I've updated the seismicity map with aftershocks of today's M7.7 earthquake in Caribbean in purple. All are to West of mainshock epicenter & most clustered at about 200 km, suggesting rupture propagated to West & has length of ~200 km (expected for M7.7). pic.twitter.com/Ee2NTFOR0Z
— Jascha Polet (@CPPGeophysics) January 29, 2020
M 7.7 – 125km NNW of Lucea, Jamaica
2020-01-28 19:10:25 (UTC) pic.twitter.com/Oiyj7sFzuT— Alan Kafka (@Weston_Quakes) January 29, 2020
Here is the IRIS interpreted version of their similar section for reference: https://t.co/byjiAkbhLI
— Mark Vanstone (@wmvanstone) January 28, 2020
Jamaica had some tremors 🥴 pic.twitter.com/pubHU8ULHT
— kendrabradia (@kendrabradia) January 28, 2020
There was just a 7.3 magnitude earth quake in Jamaica.
In my apt in Miami – this just happened.
Could feel the whole building swaying.
Crazy! pic.twitter.com/r5pPJzcLvm
— Nunya Bizniz (@Pladizow) January 28, 2020
More sinkholes appear in towns in Jamaica after a 7.7 magnitude earthquake strikes off the coast of Cuba and Jamaica. pic.twitter.com/b2yaVOHkMp
— 🗞️🇻🇮 State of the Territory News (@sottvi) January 28, 2020
#EarthquakeUpdate Tsunami Map showing areas of Jamaica that could be impacted by waves (in yellow) not exceeding 3 feet pic.twitter.com/WeLZUGhGTZ
— ODPEM (@odpem) January 28, 2020
It’s getting really wild out there in Jamaica 😐 #earthquake #jamaica pic.twitter.com/X82CyHCBA2
— kendrabradia (@kendrabradia) January 28, 2020
The tanks are part of the Cayman Water West Bay facility.https://t.co/MTioQQPKxI pic.twitter.com/cCruNnS1e5
— bbdd333 (@bbdd333) January 29, 2020
The direction a fault ruptures in an earthquake can affect the intensity of shaking. Using methods like back-projection and finite fault modeling (FFM) helps determine this directivity. https://t.co/LjR89f2p1q
— Dr. Kasey Aderhold (@kaseyaderhold) January 28, 2020
Mw=7.8, CUBA REGION (Depth: 27 km), 2020/01/28 19:10:25 UTC – Full details here: https://t.co/NLpq1TBmAc pic.twitter.com/tU0JMJB6Eg
— Earthquakes (@geoscope_ipgp) January 28, 2020
On the Oriente fault, 1962 and 1917 #earthquakes are the strongest events before the network set-up, resp. M6.1 and M7. From Van Dusen and Doser, 2000 https://t.co/iy8OnA9r8Z pic.twitter.com/YG8woSpENn
— Stéphane Baize (@stef92320) January 28, 2020
Earthquake my family in Cayman Islands pic.twitter.com/Vh8njK0SRs
— Jeannine Brown (@Jeannin54070867) January 28, 2020
Mw7.7 #earthquake #Cuba Region #Jamaica #CaymanIslands@QuakeEarly Mwpd magnitude indicated Mw7.8 only 6min after origin time.
Mwpd is a rapid size estimate for very large and very long duration earthquakes; for tsunami warning.https://t.co/IjO3uk81xJhttps://t.co/INpfQ6nPJa pic.twitter.com/twnPxiZrkC
— Anthony Lomax 🌍🇪🇺 (@ALomaxNet) January 29, 2020
Let's talk about earthquake shaking. Ppl who feel earthquakes sometimes talk about "rollers" versus "shakers." The shaking you feel in any earthquake depends to some extent on geology: if you live in a valley, you tend to feel waves sloshing, or rolling.
— Susan Hough (@SeismoSue) January 29, 2020
Looks as if there was a tiny little #tsunami (few centimetres) caused by the M7.7 #earthquake in the #Caribbean yesterday. Gauge data from https://t.co/GfWqeHMv4r pic.twitter.com/Z4FMh8iSxq
— Christoph Gruetzner (@ch_gruetze) January 29, 2020
— Jason "Jay" R. Patton (@patton_cascadia) February 1, 2020
- 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
- Benz, H.M., Tarr, A.C., Hayes, G.P., Villaseñor, Antonio, Furlong, K.P., Dart, R.L., and Rhea, Susan, 2011. Seismicity of the Earth 1900–2010 Caribbean plate and vicinity: U.S. Geological Survey Open-File Report 2010–1083-A, scale 1:8,000,000.
- Franco, A., C. Lasserre H. Lyon-Caen V. Kostoglodov E. Molina M. Guzman-Speziale D. Monterosso V. Robles C. Figueroa W. Amaya E. Barrier L. Chiquin S. Moran O. Flores J. Romero J. A. Santiago M. Manea V. C. Manea, 2012. Fault kinematics in northern Central America and coupling along the subduction interface of the Cocos Plate, from GPS data in Chiapas (Mexico), Guatemala and El Salvador in Geophysical Journal International., v. 189, no. 3, p. 1223-1236. DOI: https://doi.org/10.1111/j.1365-246X.2012.05390.x
- Garcia-Casco, A., Projenza, J.A., Iturralde-Vinent, M.A., 2011. Subduction Zones of the Caribbean: the sedimentary, magmatic, metamorphic and ore-deposit records UNESCO/iugs igcp Project 546 Subduction Zones of the Caribbean in Geologica Acta, v. 9, no., 3-4, p. 217-224
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References:
Basic & General References
Specific References
Return to the Earthquake Reports page.
This M 6.7 earthquake was the result of slip probably along a left-lateral strike-slip fault associated with the East Anatolia fault zone (EAF). The event was shallow and produced strong ground shaking in the region. https://earthquake.usgs.gov/earthquakes/eventpage/us60007ewc/executive As I write this, there have been about 5 building collapses and 22 deaths. The high number of deaths may be due to the building design used in the region. The EAF accommodates the relative plate motion between the Anatolia and Arabia plates. Because the northern motion of the Arabia plate is oblique to the plate boundary, the tectonic strain (deformation of the Earth) is proportioned on different fault types. We call this strain partitioning. The lateral strain is localized along the EAF in the form of strike-slip faults. The compressive strain formed the Southeast Anatolia fault zone, a series of imbricate thrust faults south and east of the EAF. Further to the west, this north-south compression results in the subduction of the Africa plate northwards beneath the Anatolia and Eurasia plates. This subduction forms the Hellenic trench. On the northern part of Turkey is bordered by a right-lateral strike-slip fault, the North Anatolia fault. Last year (2019) was the 20 year commemoration of the 1999 Izmit M 7.6 earthquake. The M 6.7 earthquake may have caused landslides or liquefaction in places, but the chances of this are modest at best. Geologists have studied the EAF and subdivided the fault into segments based on their mapping efforts. This M 6.7 is within the Pütürge segment of the EAF. If we look at the historic record of the EAF here, we find that the M 6.7 happened in a part of the fault that does not have an historic rupture. There was an earthquake in 1875 that appears to end to the north of the M 6.7 and there is an earthquake in 1893 that appears to terminate just to the south of the M 6.7.
Tectonic setting of continental extrusion in eastern Mediterranean. Anatolia-Aegean block escapes westward from Arabia-Eurasia collision zone, toward Hellenic subduction zone. Current motion relative to Eurasia (GPS [Global Positioning System] and SLR [Satellite Laser Ranging] velocity vectors, in mm/yr, from Reilinger et al., 1997). In Aegean, two deformation regimes are superimposed (Armijo et al., 1996): widespread, slow extension starting earlier (orange stripes, white diverging arrows), and more localized, fast transtension associated with later, westward propagation of North Anatolian fault (NAF). EAF—East Anatolian fault, K—Karliova triple junction, DSF—Dead Sea fault,NAT—North Aegean Trough, CR—Corinth Rift.Box outlines Marmara pull-apart region, where North Anatolian fault enters Aegean.
Tectonic map of the Aegean and eastern Mediterranean region showing the main plate boundaries, major suture zones, fault systems and tectonic units. Thick, white arrows depict the direction and magnitude (mm a21) of plate convergence; grey arrows mark the direction of extension (Miocene–Recent). Orange and purple delineate Eurasian and African plate affinities, respectively. Key to lettering: BF, Burdur fault; CACC, Central Anatolian Crystalline Complex; DKF, Datc¸a–Kale fault (part of the SW Anatolian Shear Zone); EAFZ, East Anatolian fault zone; EF, Ecemis fault; EKP, Erzurum–Kars Plateau; IASZ, Izmir–Ankara suture zone; IPS, Intra–Pontide suture zone; ITS, Inner–Tauride suture; KF, Kefalonia fault; KOTJ, Karliova triple junction; MM, Menderes massif; MS, Marmara Sea; MTR, Maras triple junction; NAFZ, North Anatolian fault zone; OF, Ovacik fault; PSF, Pampak–Sevan fault; TF, Tutak fault; TGF, Tuzgo¨lu¨ fault; TIP, Turkish–Iranian plateau (modified from Dilek 2006).
A: Tectonic map of the Aegean and Anatolian region showing the main active structures
C: GPS velocity field with a fixed Eurasia after Reilinger et al. (2010) D: the domain affected by distributed post-orogenic extension in the Oligocene and the Miocene and the stretching lineations in the exhumed metamorphic complexes.
E: The thick blue lines illustrate the schematized position of the slab at ~150 km according to the tomographic model of Piromallo and Morelli (2003), and show the disruption of the slab at three positions and possible ages of these tears discussed in the text. Velocity anomalies are displayed in percentages with respect to the reference model sp6 (Morelli and Dziewonski, 1993). Coloured symbols represent the volcanic centres between 0 and 3 Ma after Pe-Piper and Piper (2006). F: Seismic anisotropy obtained from SKS waves (blue bars, Paul et al., 2010) and Rayleigh waves (green and orange bars, Endrun et al., 2011). See also Sandvol et al. (2003). Blue lines show the direction of stretching in the asthenosphere, green bars represent the stretching in the lithospheric mantle and orange bars in the lower crust.
G: Focal mechanisms of earthquakes over the Aegean Anatolian region.
Schematic map of the principal tectonic settings in the Eastern Mediterranean. Hatching shows areas of coherent motion and zones of distributed deformation. Large arrows designate generalized regional motion (in mm a21) and errors (recompiled after McClusky et al. (2000, 2003). NAF, North Anatolian Fault; EAF, East Anatolian Fault; DSF, Dead Sea Fault; NEAF, North East Anatolian Fault; EPF, Ezinepazarı Fault; CTF, Cephalonia Transform Fault; PTF, Paphos Transform Fault.
The main fault systems of the AN–AR and TR–AF plate boundaries (modified from Sengor & Yılmaz 1981; Saroglu et al. 1992a, b; Westaway 2003; Emre et al. 2011a, b, c). Arrows indicate relative plate motions (McClusky et al. 2000). Abbreviations: AN, Anatolian microplate; AF, African plate; AR, Arabian plate; EU, Eurasian plate; NAFZ, North Anatolian Fault Zone; EAFZ, East Anatolian Fault Zone; DSFZ, Dead Sea Fault Zone; MF; Malatya Fault, TF, Tuzgo¨lu¨ fault; EF, Ecemis¸ fault; SATZ, Southeast Anatolian Thrust Zone; SS, southern strand of the EAFZ; NS, northern strand of the EAFZ.
Map of the East Anatolian strike-slip fault system showing strands, segments and fault jogs. Abbreviations: FS, fault Segment; RB, releasing bend; RS, releasing stepover; RDB, restraining double bend; RSB, restraining bend; PB, paired bend; (1) Du¨zic¸i–Osmaniye fault segment; (2) Erzin fault segment; (3) Payas fault segment; (4) Yakapınar fault segment; (5) C¸ okak fault segment; (6) Islahiye releasing bend; (7) Demrek restraining stepover; (8) Engizek fault zone; (9) Maras¸ fault zone.
Map of the (a) Palu and (b) Puturge segments of the East Anatolian fault. Abbreviations: LHRB, Lake Hazar releasing bend; PS, Palu segment; ES, Erkenek segment; H, hill; M, mountain; C, creek; (1) left lateral strike-slip fault; (2) normal fault; (3) reverse or thrust fault; (4) East Anatolian Fault; (5) Southeastern Anatolian Thrust Zone; (6) syncline;(7) anticline; (8) undifferentiated Holocene deposits; (9) undifferentiated Quaternary deposits; (10) landslide.
Surface ruptures produced by large earthquakes during the 19th and 20th centuries along the EAF. Data from Arpat (1971), Arpat and S¸arog˘lu (1972), Seymen and Aydın (1972), Ambraseys (1988), Ambraseys and Jackson (1998), Cetin et al. (2003), Herece (2008), Karabacak et al. (2011) and this study. Ruptured fault segments are highlighted.
The Global Seismic Hazard Map. Peak ground acceleration (pga) with a 10% chance of exceedance in 50 years is depicted in m/s2. The site classification is rock everywhere except Canada and the United States, which assume rock/firm soil site classifications. White and green correspond to low seismicity hazard (0%-8%g), yellow and orange correspond to moderate seismic hazard (8%-24%g), pink and dark pink correspond to high seismicity hazard (24%-40%g), and red and brown correspond to very high seismic hazard (greater than 40%g).
#EarthquakeReport for #depremElazig #Deprem #Earthquake in #Turkey Posters here I have tweeted before, now there is a report to explain them. I will update this report over time — Jason "Jay" R. Patton (@patton_cascadia) January 25, 2020 #EarthquakeReport pages can now be translated on https://t.co/fGEEJoACJA by simply clicking the language on the upper right. Uses Google Translate plugin "GTranslate: for WordPress" pic.twitter.com/hkLvy8VlAq — Jason "Jay" R. Patton (@patton_cascadia) January 26, 2020 Mw=6.7, TURKEY (Depth: 23 km), 2020/01/24 17:55:14 UTC – Full details here: https://t.co/rL50XD3kRs pic.twitter.com/uBFWy5q1hN — Earthquakes (@geoscope_ipgp) January 24, 2020 very strong and dangerous #earthquake #deprem along border of #Turkey and #Syria near #Elazig and #Malatya, felt widely including as far as #Istanbul and all over the Middle East Due to crisis situation in this region, impact estimates are difficult@ShakingEarth pic.twitter.com/Z1EPX0byHi — CATnews | Andreas M. Schäfer (@CATnewsDE) January 24, 2020 Map of felt reports received so far following the #earthquake M6.9 in Eastern Turkey 40 min ago pic.twitter.com/RXQx9Vkbw3 — EMSC (@LastQuake) January 24, 2020 Updated aftershock map of Jan 24 Mw6.8 #earthquake near Sivrice, Elazığ (eastern Turkey); >60km rupture along the Pütürge Segment of East Anatolia Fault Zone. Epicenters & focal mechanism from AFAD, active fault traces from MTA. Latest #Landsat8 image from Jan 22. pic.twitter.com/YR45rY6C1z — Sotiris Valkaniotis (@SotisValkan) January 25, 2020 Watch the waves from the M6.7 Turkey #earthquake roll across the USArray Transportable Array seismic network (https://t.co/RIcNz4bgWq ). #TurkeyEarthquake (THREAD) pic.twitter.com/UoxtaFVOQ6 — IRIS Earthquake Sci (@IRIS_EPO) January 24, 2020 Mw6.9 #earthquake in eastern #Turkey. Possible activation of Pütürge Segment, East Anatolia Fault. Preliminary locations of the epicenter, and GFZ focal mech. Fault map from Duman & Emre (2013) pic.twitter.com/iot7Rb58EA — Sotiris Valkaniotis (@SotisValkan) January 24, 2020 The @USGS generates finite fault models for larger EQs, where they try to reconstruct the quake. For the #TurkeyEarthquake, their prelim estimate is ~20 seconds of rupture, or 20 seconds just for the fault(s) to break. This is different from how long the earth shook. https://t.co/ln4bqol3OU — Alka Tripathy-Lang, PhD (@DrAlkaTrip) January 25, 2020 🗺 New map: [#EMSR423] Elazig: Grading Product, version 1, release 1, RTP Map #01 [v1, 1:30000] — Copernicus EMS (@CopernicusEMS) January 25, 2020 29 dead, 1,466 injured as massive quake of magnitude 6.8 rocks Turkey's Elazığ https://t.co/HaUzX5C8hR — Jason "Jay" R. Patton (@patton_cascadia) January 25, 2020 The Elazig earthquake from a 6-day Sentinel-1 pair (@ESA_EO @CopernicusData), processed using ISCE. The colour gradient from red to blue (instead of a sharp discontinuity) suggests that most of the slip occurred at depth and did not make it to the surface (intriguing…) pic.twitter.com/gZcqhs1wsq — Gareth Funning (@gfun) January 28, 2020
Welcome to the next decade of the 21st century. We may look back a decade to review the second most deadly earthquake in the 21st century, from the magnitude M 7.0 Haiti Earthquake on 12 Jan 2010. I put together an overview of this event sequence here. The latest aftershock forecast was tweeted here. I hope people follow this link to stay up to date on these forecasts. Aftershocks have continued in #PuertoRico, with 144 magnitude 3.0 and greater aftershocks recorded since the M6.4 quake on Jan 7. Current models estimate about an 11% chance for future aftershocks of M6.0 or greater. Daily updates can be found at: https://t.co/WFthaXL9vp — USGS (@USGS) January 12, 2020
In so-called ‘earthquake swarms’, numerous earthquakes occur locally over an extended period without a clear sequence of foreshocks, main quakes and aftershocks. The Swiss Seismological Service (SED) registers several of earthquakes swarms every year. They are therefore nothing extraordinary. Swarms usually end after a few days or months. Only seldom does the strength and number of earthquakes increase over time or do occur single, damaging events. How an earthquake swarm develops over time is just as difficult to predict as earthquakes are in general.
Many earthquake swarms occur in regions with complex contiguous fracture systems. The theory is that they are related to the movement of fluid gases and liquids in the Earth’s crust.
Seismotectonic setting of the Caribbean region. Black lines show the major active plate boundary faults. Colored circles are precisely relocated seismicity [1960–2008, Engdahl et al., 1998] color coded as a function of depth. Earthquake focal mechanism are from the Global CMT Catalog (1976–2014) [Ekstrom et al., 2012], thrust focal mechanisms are shown in blue, others in red. H = Haiti, DR = Dominican Republic, MCS = mid-Cayman spreading center, WP = Windward Passage, EPGF = Enriquillo Plaintain Garden fault
Seismicity and kinematics of the NE Caribbean. The inset shows Caribbean and surrounding plates, red arrows show relative motions in cm/yr: a: NEIC seismicity 1974–2015 is shown with circles colored as a function of depth, stars show large (M > 7) instrumental and historical earthquakes; b: red and blue bars show earthquake slip vector directions derived from the gCMT database [www.globalcmt.org], black arrows show the present-day relative motion of the NA plate with respect to the Caribbean.
Contoured bathymetry map of the northeastern Caribbean showing a summarized tectonic setting. Isobaths based on satellite-derived bathymetry gridded at 1 arcminute intervals (Smith and Sandwell, 1997) using the free software Generic Mapping Tools (GMT; Wessel and Smith, 1998). The purple dashed rectangle marks the study area. Thick green arrows show the relative convergence motion between the North American and the Caribbean plates. GPS-derived velocities with respect to the North American plate are shown with thin red arrows, the arrow length being proportional to the displacement rate (Manaker et al., 2008). Error ellipse for each vector represents two-dimensional error, 95% confidence limit. The thick blue dashed line marks the Hispaniola-PRVI block boundary as suggested by ten Brink and Lopez-Venegas (2012). The green area shows the extension of the Muertos thrust belt (Granja Bru~na et al., 2009, 2014, this study). NOAM ¼ North American. CARIB ¼ Caribbean. EPGFZ ¼ Enriquillo-Plantain Garden fault zone. SFZ ¼ Septentrional fault zone. BF ¼ Bunce fault. SB ¼ Sombrero basin. PRVI BLOCK ¼ Puerto RicoeVirgin Islands block. VIB ¼ Virgin Islands basin. MR ¼ Mona rift. IFZ ¼ Investigator fault zone. JS ¼ Jaguey spur. SCR ¼ St. Croix rise. SCI ¼ St. Croix Island. The inset map shows GPS-derived velocities with respect to St. Croix Island (SCI), the arrow length being proportional to the displacement rate (ten Brink and Lopez-Venegas, 2012). Error ellipse for each vector represents two-dimensional error, 95% confidence limit. MI ¼ Mona Island. CI ¼ Culebra Island. STI ¼ St. Thomas Island. AI ¼ Anegada Island. SCI ¼ St. Croix Island. IFZ ¼ Investigator fault zone.
Map of Puerto Rico showing known and possible Quaternary-active faults. Well-located faults are shown by solid lines; inferred fault locations are shown by dashed lines. The northwest end of the Great Southern Puerto Rico fault zone (GSPRFZ) likely follows the Cerro Goden fault, but an alternative location shown by Jansma et al. (2000) and Jansma and Mattioli (2005) is indicated by the dashed lines. The GSPRFZ is shown by double lines because the fault zone mapped in bedrock is up to 2 km wide. Map base is a digital elevation model (DEM) created from 30-m (∼1 arcsec) National Elevation Dataset (NED) (see Data and Resources). Bathymetric contours are from ten Brink et al. (2004).
Regional morphotectonic interpretation. Faults picked from the seismic data and correlated along strike with the aid of swath bathymetry data. Thick orange lines mark the major onshore structures (GSPRFZ ¼ Great Southern Puerto Rico fault zone; LVF ¼ Lajas Valley fault). Thin orange lines show the faults mapped by Bawiec (1999). FC ¼ Frederickted canyon. WIFZ ¼ Western sector of the Investigator fault zone. CIFZ ¼ Central sector of the Investigator fault zone. EIFZ ¼ Eastern sector of the Investigator fault zone. PF ¼ Ponce fault. BTF ¼ Bajo Tasmanian fault. CMF ¼ Caja de Muertos fault. CF ¼ Central fault. MPC ¼ Mona passage canyon. R ¼ Recess. S ¼ Salient in the deformation front. Ss ¼ Salient in the deformation front referred in Section 4.1. JP ¼ Jungfern passage. WC ¼ Whiting canyon. VC ¼ Vieques canyon. Z ¼ Bench in the northern flank of St. Croix rise. PRSBF ¼ Puerto Rican sub-basin fault. RR ¼ Relay ramp.W¼ Canyon referred to in Section 4.4.3. Q ¼ 080-oriented fault in Section 4.4.3. T ¼ possible source of the 1867 earthquake (Barkan and ten Brink, 2010) referred in Section 5.2.
(top) GPS velocities used in the model shown with respect to the North American plate defined by the velocity of 25 GPS sites located in the stable interior of the plate [Calais et al., 2006]. (bottom) GPS velocities shown with respect to the Caribbean plate as defined in the best fit block model described in the text. Error ellipses are 95% confidence. Blue arrows show GPS velocities from Pérez et al. [2001] in Venezuela because of their large uncertainty and the lack of common sites with our solution, which prevents us from rigorously combining them to our solution. They are not used in the model but used to show that they are consistent with the rest of the velocity field.
Earthquake focal mechanisms [Ekstrom et al., 2012] and locations [Engdahl et al., 1998] along the subduction interface and cross sections showing with a thick black line the position of the Caribbean-North America plate interface used in the model. Other faults are shown with thick dashed black lines. SF = Septentrional fault, PRT = Puerto Rico trench, MT = Muertos trench, LAT = Lesser Antilles trench, NHT = Northern Hispaniola trench. White dots on the map (top) show the vertices of the triangles used to discretize the subduction interface. Grey lines on cross section show the bathymetry with significant vertical exaggeration compared to the earthquake depth scale. The area used for each cross
Hypothesized model of the tectonic relationships. The PRVI sits between two subducting slabs; the dip angles of the two subducting slabs increase from east to west. The North American Plate splits in the eastern PRVI (modified after ten Brink, 2005). North arrow is black. Red arrows show the directions of movement for the PRVI and Hispaniola microplate with respect to the North American Plate. The light grey area at the centre is above 2 km bathymetry line. PRVI, Puerto Rico Virgin Islands; AP, Anegada Passage
Sections across the Lesser and Greater Antilles subduction showing topography (grey line), earthquake hypocenter [Engdahl et al., 1998], velocity magnitude at the GPS sites (red circles with 95% confidence error bar), velocity predicted by the best fit model (solid red line), and velocity predicted by a forward model where we impose full coupling on the subduction interface (dashed blue line). The misfit of the data to a fully locked plate interface is apparent on the three Lesser Antilles cross sections.
Velocities at selected GPS sites in the NE Caribbean shown with respect to the Caribbean plate (a) and to the North American plate (b). Error ellipses are 95% confidence.
Block geometry used in the models tested. Solid black lines show the block boundaries for the best fit model, thick dashed lines show other tested block boundaries. NHIS = North Hispaniola, PRVI = Puerto Rico and Virgin Islands, GONA = Gonave, HISP = Hispaniola, NLAB = North Lesser Antilles Block, SJAM = South Jamaica. CARW = Caribbean West, CARE = Caribbean East, NVEN = North Venezuela, MARA = Maracaibo, ANDE = Andes, HFBT = Hispaniola fault and thrust belt, NMF = Neiba-Matheux thrust, SJF = South Jamaica fault. Thin dashed lines are depth contours of the subduction interface used in the model, derived from the earthquake hypocenters cross sections shown in Figure 4.
Coupling ratio estimated along the Greater-Lesser Antilles subduction interface estimated on the discretized plate interface also shown in Figure 4. Residual velocities are shown with black arrows. We omitted their error ellipses for a sake of readability. The thin dashed line indicates the boundary of the Bahamas Platform. Note the coincidence between the transition from coupled to uncoupled plate interface with the transition from Bahamas Platform collision to oceanic subduction at the Puerto Rico trench.
Fault slip rates and slip rate deficit from the best-fit model. Open circles represent the surface projection of fault nodes. Heavy black lines show the model block boundaries. Vertical faults are shown to the right of each main figure. (a) Fault slip rates (mm yr−1). (b) Slip rate deficit (mm yr−1).
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 (so far) the mainshock M6.4 #Earthquake in #PuertoRico #PuertoRicoEarthquake #terremoto #TremblementDeTerre #temblor minor #tsunami 5cm at Magueyes Island tide gagehttps://t.co/J5jfn8LJWvhttps://t.co/Vh4RcbVMCN EQ history here https://t.co/eH5gBgIkYT pic.twitter.com/CXuTjdDU1y — Jason "Jay" R. Patton (@patton_cascadia) January 7, 2020 "In so-called 'earthquake swarms', numerous earthquakes occur locally over an extended period without a clear sequence of foreshocks, main quakes and aftershocks", from @seismoCH_E: https://t.co/wZqNJd1YFS pic.twitter.com/qBXfB0TQ1i — Dr. Kasey Aderhold (@kaseyaderhold) January 11, 2020 Puerto Rico has been hit by spate of damaging M5-6 earthquakes over the past few days. All this shaking is due to Puerto Rico’s location along the edge of the Caribbean plate. This adds to the damage still present from Hurricane Maria: https://t.co/cQ82kTD7g0 @DiscoverMag pic.twitter.com/v2fTav0oYe — Dr. Erik Klemetti (@eruptionsblog) January 7, 2020 Animation from the Interactive Earthquake Browser showing #earthquakes near #PuertoRico between Nov 1, 2019 and Jan 7, 2020 (8 am). The color of the dots indicates the depth (purple means shallow) and the size of the dot indicates the magnitude. https://t.co/Gs3ykBEp0y pic.twitter.com/EBzkXgzumD — IRIS Earthquake Sci (@IRIS_EPO) January 7, 2020 Auto solution FMNEAR (Géoazur/OCA) with regional records for the 2020-01-07 08:24:26 UTC M6.5 PUERTO RICO 17.87N 66.79W 10km depth (Loc EMSC used to trigger inversion).https://t.co/UHDsc1hVXA (not on mobile version) — Bertrand Delouis (@BertrandDelouis) January 7, 2020 Backprojection of the M6.4 #PuertoRicoEarthquake pic.twitter.com/FaACUzK9ks — IRIS Earthquake Sci (@IRIS_EPO) January 7, 2020 The movie. Perspective view from SE rotating to NE. Swarm seismicity suggests steeply NNE dipping structures above ~12km, and deeper, N-S & WNW-ESE vertical faulting within a gently N dipping structure which continue northwards under Puerto Rico at base of background seismicity. pic.twitter.com/a3sA5C5JF2 — Anthony Lomax 🌍🇪🇺 (@ALomaxNet) January 12, 2020 NASA JPL image release of displacement map for Puerto Rico earthquake, from #InSAR processing of Copernicus Sentinel-1 data. https://t.co/wEJQ8tQ4dm@NASAJPL pic.twitter.com/dVURwkBawQ — Eric Fielding (@EricFielding) January 11, 2020 PR is more used to dealing with hurricanes than earthquakes. Due of this, housing is mostly concrete and worse, elevated on piers (carports/flooding). Both aspects make them more vulnerable to EQs. These pics are from a few days ago from smaller eqs on PR #PuertoRicoEarthquake pic.twitter.com/IXRdP0mBNP — Forrest Lanning (@rabidmarmot) January 7, 2020 #EarthquakeReport Shaking Intensity from @USGSBigQuakes for M 6.4 #Earthquake in #PuertoRico #PuertoRicoEarthquake #Terremoto #TremblementDeTerre #Temblor #TemblorPuertoRico #TemblorPR #TemblorEnPuertoRico pic.twitter.com/RfJpjoUVmF — Jason "Jay" R. Patton (@patton_cascadia) January 7, 2020 — Jason "Jay" R. Patton (@patton_cascadia) January 7, 2020 Dozens of earthquakes, some as large as M5-6, have struck the southern coast of Puerto Rico over the past few days. After Hurricane Maria, these quakes add to the challenge of recovery on the Carribbean island (Image: USGS) https://t.co/cQ82kTUIEA @DiscoverMag pic.twitter.com/zFPcAN77We — Dr. Erik Klemetti (@eruptionsblog) January 7, 2020 No todos los heroes tienen capa pic.twitter.com/07WqFgXeh6 — htj (@htjlaw) January 7, 2020 Seismo Blog: Deadly Earthquakes in the Muertos Trough — Berkeley Seismo Lab (@BerkeleySeismo) January 7, 2020 Watch the waves from the M6.4 #PuertoRicoEarthquake roll across the USArray Transportable Array seismic network (https://t.co/RIcNz4sRNY )! pic.twitter.com/0bWbX3SgTS — IRIS Earthquake Sci (@IRIS_EPO) January 7, 2020 #PuertoRico 🇵🇷 en estado de emergencia, tras los fuertes sismos de hoy. — Geól. Sergio Almazán (@chematierra) January 7, 2020 Central Meteorológica y Geológica del Caribe pública las siguientes fotos en Facebook de la escuela Agripina Seda en Guanica. pic.twitter.com/y3CkkGuHVV — Nuria Sebazco (@nsebazco) January 7, 2020 https://t.co/ikNyzpw9xJ #TemblorPR #TemblorEnPuertoRico #earthquakes pic.twitter.com/mJT89HqyLl — temblor (@temblor) January 8, 2020 https://t.co/ikNyzpNKph #TemblorPR #TemblorEnPuertoRico #earthquakes pic.twitter.com/867UGoTgcw — temblor (@temblor) January 8, 2020 #EarthquakeReport interpretive poster showing potential for earthquake induced liquefaction from M6.4 #PuertoRicoEarthquake #PuertoRico #EarthquakePR #EarthquakePuertoRico from @USGSBigQuakes modeling here https://t.co/IszgHm9rL4 — Jason "Jay" R. Patton (@patton_cascadia) January 8, 2020 — Jason "Jay" R. Patton (@patton_cascadia) January 8, 2020 A few #landslides triggered by the recent Puerto Rico #earthquake, near the Mw 6.4 epicenter area. #Sentinel2 upscaled image comparison for Dec 29 and Jan 8. Location ~10km east of Guánica, along the southern coast. pic.twitter.com/c0OuhGu3OK — Sotiris Valkaniotis (@SotisValkan) January 8, 2020 Quickly drawn idea. Turns out that the Great Southern Puerto Rico Fault is further east of Ponce, following the Rio Grande de Anasco north of the current sequence – I have found few detailed or helpful fault maps for Puerto Rico, hence my error. pic.twitter.com/bQNYFmF4kT — Jamie Gurney (@UKEQ_Bulletin) January 9, 2020 USGS forecasts a 3 percent chance of one or more aftershocks larger than a magnitude 6.4 in Puerto Rico in the next week and that smaller earthquakes are likely to occur. Forecasts are updated periodically and official information can be found here: https://t.co/YpNeR6rxQd pic.twitter.com/ainSKWbjMU — USGS (@USGS) January 9, 2020 Watching earthquakes roll in on the real time monitor 😮 Video taken by Alena Leeds and Elizabeth Vanacore, two of the folks on the @USGS+@redsismica field crew installing @usgs_seismic stations pic.twitter.com/VFiwtDZY8t — Emily Wolin (@GeoGinger) January 11, 2020 En Puerto Rico, muchos se preguntan ansiosamente ¿y ahora, qué viene? Nadie puede predecir terremotos, pero la sismología puede dar pronósticos: estimar probabilidades de que ocurran más sismos, pequeños o grandes. Lo hace @USGS https://t.co/tVUXGWrqXY Explicación 👇 pic.twitter.com/Uvt7VWJMOK — Pablo Ampuero (@DocTerremoto) January 11, 2020 The GS-PR01 station was the closest to this morning's M5.9, providing valuable strong motion recordings. pic.twitter.com/SgD4FucQCg — USGS_Seismic (@usgs_seismic) January 11, 2020 #EarthquakeReport #Earthquake #Aftershocks in #PuertoRico interpretive posters with mechanisms and comparisons (6.4 v 5.9) intensity and liquefaction susceptibility (6.4 v 5.9)#PuertoRicoEarthquakes #TerremotoPR #TerremotosPR #terremoto #terremotopuertorico #Terremotos pic.twitter.com/YANM7Uze8i — Jason "Jay" R. Patton (@patton_cascadia) January 12, 2020 Time progression of Puerto Rico earthquake sequence based on local network catalog — Jascha Polet (@CPPGeophysics) January 11, 2020 NASA JPL ARIA processing of new Copernicus Sentinel-1 #InSAR for Puerto Rico earthquakes, using data from 2020/01/02–2020/01/14 shows displacement of the land surface. The coast centered on Guayanilla Bay moved 14 cm (5.5 inches) downward in radar line-of-sight. Quakes from USGS pic.twitter.com/iwi69RHuez — Eric Fielding (@EricFielding) January 15, 2020 Update on the Southern #PuertoRico Seismic Sequence since December 27 until January 25th 00:26 am. — Janira Irizarry (@jany_ip) January 25, 2020
On 10 February 2010 there was an earthquake with a magnitude of M 6.5, within the Gorda plate. This event was feld widely in the region, as well as statewide. In Humboldt County, we even made t-shirts about this quake. I write this report after ten years of reflection. 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.
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.
Source models for earthquakes S and T, 10 January 2010, M = 6.5, and 4 February 2010, Mw = 5.9.
Coulomb stress changes imparted by the 1980 Mw = 7.3 earthquake (B) to a matrix of faults representing the Mendocino Fault Zone, the Cascadia subduction zone, and NE striking left‐lateral faults in the Gorda zone. The Mendocino Fault Zone is represented by right‐lateral faults whose strike rotates from 285° in the east to 270° in the west; Cascadia is represented by reverse faults striking 350° and dipping 9°; faults in the Gorda zone are represented by vertical left‐lateral faults striking 45°. The boundary between the left‐lateral “zone” and the reverse “zone” in the fault matrix is placed at the 6 km depth contour on Cascadia, approximated by extending the top edge of the Oppenheimer et al.
Coulomb stress changes imparted by the Shao and Ji (2005) variable slip model for the 15 June 2005 Mw = 7.2 earthquake (P) to the epicenter of the 17 June 2005 Mw = 6.6 earthquake (Q). Calculation depth is 10 km.
Coulomb stress changes imparted by the D. Dreger (unpublished report, 2010, [no longer] available at http://seismo.berkeley.edu/∼dreger/jan10210_ff_summary.pdf) model for the January 2010 M = 6.5 shock (S) to nearby faults. East of the dashed line, stress changes are resolved on the Cascadia subduction zone, represented by a northward extension of the Oppenheimer et al. [1993] rupture plane for the 1992 Mw = 6.9 Cape Mendocino earthquake. West of the dashed line, stress changes are resolved on the NW striking nodal plane for the February 2010 Mw = 5.9 earthquake (T) at a depth of 23.6 km.
This is the ten year commemoration of the 2010 magnitude 7 earthquake in Haiti that caused widespread damage and casualties, triggered thousands of landslides, caused tsunami, triggered a turbidity current, and caused thousands to be internally displaced.
Deaths from earthquakes since 1900. The toll of the Haiti quake is more than twice that of any previous magnitude-7.0 event, and the fourth worst since 1900.
Seismotectonic setting of the Caribbean region. Black lines show the major active plate boundary faults. Colored circles are precisely relocated seismicity [1960–2008, Engdahl et al., 1998] color coded as a function of depth. Earthquake focal mechanism are from the Global CMT Catalog (1976–2014) [Ekstrom et al., 2012], thrust focal mechanisms are shown in blue, others in red. H = Haiti, DR = Dominican Republic, MCS = mid-Cayman spreading center, WP = Windward Passage, EPGF = Enriquillo Plaintain Garden fault.
Hazard maps using grid of VS30 values shown in Figure 7: (top) PGA (%g) with 10% probability of exceedance, (bottom) PGA (%g) with 2% probability of exceedance in 50 years.
Tectonic setting of the northeastern Caribbean and Hispaniola. a, Major active plate-boundary faults (black lines), instrumental seismicity (National Earthquake Information Center database, 1974–present) and Caribbean–North America relative motion (arrow). P.R. Puerto Rico; D.R. Dominican Republic. b, Summary of the present-day tectonic setting of Hispaniola. Estimated historical rupture areas are derived from archives. 1860, 1953 and 1701 are the dates of smaller magnitude, poorly located events. Vertical strike-slip events are shown as lines; dip-slip events are shown as projected surface areas. The red arrows show geodetically inferred long-term slip rates (labelled in mmyr-1) of active faults in the region from the block model discussed here (the arrows show motion of the southern with respect to the northern block).
Tectonic setting and active faulting in Haiti. (a) Major anticlines (lines with arrows, dashed white: growing and grey: older), active thrusts (black), and strike-slip faults (EPGF and SF: in red) from this study [Mann et al., 1995; Pubellier et al., 2000; Mauffret and Leroy, 1997; Granja Bruña et al., 2014]. Blue (1): rigid Beata oceanic crust block. Dark purples: toleitic complex oceanic crust outcrops. Orange: Cul-de-Sac and Enriquillo (CSE) ramp basins; brown (2): Hispaniola volcanic arc. Black crosses: metamorphic Cretaceous basement; yellow: rigid Bahamas bank. Haiti FTB: Haiti fold and thrust belt. Grey line: trench. Double black arrows: regional compression deduced from mean orientations of folds and thrusts. (b) Active faulting in southern Haiti. Topography and bathymetry (contours each 200 m) from Global Multi-Resolution Topography (GMRT) synthesis (http://www.geomapapp.org). Faults, folds, and symbols as in Figure 1a. Simple red and black arrows: strike-slip motion. In orange: push-down troughs of Port-au-Prince Bay and Azuei and Enriquillo Lakes in the CSE ramp basin. Inset (bottom left): fault geometry and kinematics. Grey ellipse: zone with en echelon troughs in N100°E direction. Inset (top right): simplified strain ellipse in southern Haiti.
(a) Active faulting and seismicity in the southeastern part of Haiti. Topography and bathymetry (contours each 100 m), from Advanced Spaceborne Thermal Emission and Reflection (http://asterweb.jpl.nasa.gov/) and Shuttle Radar Topography Mission 30+ (http://www2.jpl.nasa.gov/srtm/), respectively, and the 1:25000 bathymetric chart of the Hydrographic and Oceanographic Department of the French Navy (contours at 2, 5, 10, 20, 30, 50, 100, and 130m) in the Port-au-Prince Bay. Faults, folds, and symbols as in Figure 1. Red star: 2010 main shock epicenter from Mercier de Lépinay et al. [2011] with the centroid moment tensor from Harvard University (http://www.globalcmt.org); seismicity from Douilly et al. [2013], and focal mechanisms from Nettles and Hjörleifsdóttir [2010]. Location of Figure 3a is indicated. PAP, Port-au-Prince. Folds in CSE ramp basin with locations of Figures 4a and 4b are indicated: PaPT: Port-au-Prince thrust; DT: Dumay thrust; NaC: Nan Cadastre thrust (see Figure 4b); Jac: Jacquet thrust; Gan: Ganthier thrust (see figure 4a). Red and white star near DT: location of Figure 4d. (b) NNE-SSW geological cross section across the Cul-de-Sac-Enriquillo plain. Geology from www.bme.gouv.ht and Mann et al. [1991b] (supporting information Figure S5) with colors of units as in Figure 2c. Profile location shown in Figure 2a; topography as in Figure 1. No vertical exaggeration. (c) Three-dimensional block diagram showing the geology, the aftershocks [from Douilly et al., 2013], and the fault system along a N-S cross section (location in Figure 2a). The block highlighted in red is uplifting in between the LT and the EPGF.
(a) Active faulting in the 2010 earthquake epicentral area. Active faults, symbols, topography, and bathymetry as in Figure 2a. Location of Figure 3b is indicated. SSW-NNE topographic profiles are shown in the inset. ΔR: fault throw at the seafloor. Vertical exaggeration (VE): 20X; α: slope of the Léogâne delta fan. (b) The Lamentin thrust in Carrefour. Topography from lidar data (contours at 5m vertical interval). Rivers in blue, with thicker traces for larger ones. Inset in the lower left corner: topographic profile BB′ along of the Lamentin fold crest (VE: 5X). Inset in the upper right corner: topographic profile AA′ perpendicular to the Lamentin thrust system (VE: 2.5X) and the most plausible geometry of the thrusts (with no vertical exaggeration). In yellow: upper Miocene limestone; in grey: Quaternary conglomerates. MT:main thrust. The width of the fold and the slope of the fan surface constrain the rooting depth of the emergent ramp to the décollement [e.g.,Meyer et al., 1998].
Active folding in the Cul-de-Sac-Enriquillo ramp basin. (a) Aerial photograph of the 8 km long Ganthier Quaternary fold. (b) Lidar topography of the Nan Cadastre Quaternary thrust folding. Inset: topographic profile AA′ and possible interpretation at depth. (c) Field photograph along the eastern flank of the Bois Galette River (location in Figure 4a) showing the folded alluvial sediments of the Ganthier fold dipping ~30°N. (d) Field photograph and interpretation of the 50 ± 15° southward dipping Dumay thrusts (in red) exposed in cross section on the eastern bank of the Rivière Grise (location in Figure 2a). The fault offsets by several tens of centimeters Quaternary sediments (lacustrine and conglomerates) incised by the river.
Interseismic GPS velocities. The GPS velocity field is determined from GPS campaigns before the 12 January 2010 earthquake. The ellipses and error bars are 95% confidence. a, Velocities with respect to the North American plate. b, Velocities with respect to the Caribbean plate. c, Velocity profile perpendicular to the plate boundary (coloured circles and one-sigma error bars) and best-fit elastic block model (solid lines). Blue D profile-perpendicular (‘strike-slip’) velocity components; orange D profile-parallel (‘shortening’) velocity components. The profile trace and width are indicated by dashed lines in a and b.
GPS velocities shown with respect to the North American plate (A) and to the Caribbean plate (B). Error ellipses are 95% confidence. (C) North–south profile including GPS sites shown with the dashed box shown on panels A and B. Velocities are projected onto directions parallel (blue) and normal (red) to the EPGF direction. MS = Massif de la Selle, CdS = Cul-de-Sac basin, MN= Matheux-Neiba range, PC= Plateau Central, PN= Plaine du Nord, EF= Enriquillo fault, SF= Septentrional fault.
Top and middle: comparison between the best-fit model (solid lines) and GPS observations for the strike-slip (blue) and shortening (red) components for the one– fault model, i.e. with oblique slip on the south-dipping fault. Bottom: interpretative geological cross-section using information from Saint Fleur et al. (2015). The red line indicates the model fault with its locked portion shown as solid. The surface trace of the fault in the best-fit model coincides with the northern limb of the Ganthier fold, indicated by the letter G. The gradient of GPS velocities coincides with the southern edge of the Cul-de-Sac basin, while the Matheux range appears devoid from present-day strain accumulation. D = Dumay locale where Terrier et al. (2014) report reverse faulting affecting Quaternary sediments. G = Ganthier fold (Mann et al., 1995).
Coseismic displacements from GPS measurements. a, Map of horizontal coseismic displacements. Note the significant component of shortening, similar to the interseismic velocity field (Fig. 2). The orange arrows have been shortened by 50% to fit within the map. Displacements at stations TROU and DFRT, cited in the text, are labelled. NR Can Natural
Deformation observations and rupture model. a, Interferogram (descending track, constructed from images acquired on 9 March 2009 and 25 January 2010), GPS observed (black) and model (red) coseismic displacements. The yellow circles show aftershocks. G D Greissier, L D Léogâne, PaP D Port-au-Prince. EF D Enriquillo–Plantain Garden fault. The black rectangle shows the surface projection of the modelled rupture; the black–white dashed line is the intersection with the surface. LOS displ:D line-of-sight displacement. b, Total slip distribution from a joint inversion of InSAR and GPS data, viewed from the northwest. c, Interpretative cross-section between points A and B indicated on a. The red line shows coseismic rupture.
Cross sections perpendicular to the Enriquillo fault illustrating possible fault structures. Hypocenters within the rectangular boxes are included in the corresponding cross section. The open triangles in the cross sections indicate the surface trace of the Enriquillo fault. The red line shows the main earthquake rupture on the Léogâne fault; blue lines show the Trois Baies thrust fault; green lines show south-dipping antithetic structures delineated by aftershocks possibly triggered by Coulomb stress changes following the mainshock. The black lines in the cross sections show the hypothesized location of the Enriquillo fault, which is believed to dip from 65° north (Prentice et al., 2010) to vertical.
Coulomb stress changes imparted by the January 12, 2010, Mw=7.0 rupture resolved on surrounding faults inferred from Mann and others (2002). Thrust faults dip 45°.
Coulomb stress changes imparted by the January 12, 2010, Mw=7.0 rupture to the Septentrional Fault, assuming a friction of 0.4 (a friction of 0.0 yields a similar result, with the peak stress shifted 25 km to the west). Stress changes are positive but very small. The two 1/26/10 aftershocks are the only events thus far to locate well off the source model; if they are left-lateral events on roughly E-W planes, then they would have been promoted by stress imparted by the January 12 mainshock rupture.
Newstatic slipmodel for the 2010 Haiti earthquake and induced Coulomb stress changes. (a) Axonometric view from SE showing the slip distribution on two faults (EPGF and LT) determined by modeling geodetic data (GPS and interferometry) and coastal uplift values recorded by coral (see supporting information). Arrows (white for EPGF and black for LT) indicate the motion of the hanging wall with respect to the footwall. Land surfaces in grey. Red lines: active faults. Blue bars: coastal uplift measured by using corals from Hayes et al. [2010]. Red bars: uplift predicted by our model. Focal mechanisms indicated the EPGF (dark yellow) and Lamentin fault (green) geometry. (b) Coulomb stress changes induced by the slip model we determined, in map view at 7.5 km depth. Black rectangles: modeled faults. Epicentral locations of aftershocks from Douilly et al. [2013]. Insets in the upper left corners: parameters of the receiver faults used for the Coulomb stress calculation. Calculated for receiver faults having the same geometry as the strike-slip EPGF (dark yellow lines) and as the Lamentin thrust (dark green lines), respectively (Figure 5b, left and right).
Calculated coseismic Coulomb stress change on the regional faults of southern Haiti based on coseismic slip associated with our preferred model (Fig. 5c) and two assumptions of apparent friction. The Enriquillo fault is assumed to dip 65° to the south with a rake of 20°. The Trois Baies fault is assumed to dip 55° to the north with a rake of 70°. All other faults are assumed to dip at 60° and a rake of 90° (pure
Overview of population movements. (A) Shows the geography of Haiti, with distances from PaP marked. The epicenter of the earthquake is marked by a cross. (B) Gives the proportion of individuals who traveled more than d km between day t − 1 and t. Distances are calculated by comparing the person’s current location with his or her latest observed location. In (C), we graph the change in the number of individuals in the various provinces in Haiti. (D) Gives a cumulative probability distribution of the daily travel distances d for people in PaP at the time of the earthquake. (E) Shows the cumulative probability distribution of d for people outside PaP at the time of the earthquake. Finally, (F) gives the exponent α of the power-law dependence of d—the probability of d is proportional to d−α. These are obtained by a maximum-likelihood method (33), and differ from the slopes of the lines in (D) and (E) by unity since these are the cumulative distributions.
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.
Tectonic setting and landslide distribution map of the study area. (a) Area surrounding the Mw 7.0 January 2010 Haiti earthquake epicenter; beach ball shows focal mechanism (earthquake.usgs.gov). (b) Tectonic setting of the Caribbean plate boundaries. Red star and the points are locations of main shock and major aftershock distributions, respectively. (c) Topographic setting and mean local relief (white circles with±1σ whiskers) of pre- and post-earthquake landslides: alluvial plains and fans (APF), coastal cliff (CSC), deeply incised valley (DIV), dissected hilly and mountainous terrain (HDHM), round crested slopes and hills (RLH), moderately steep slopes (MR), plateau escarpments (PE), and steep faulted hills (SFH).
Distribution of (a) coseismic and (b) aseismic landslides along a reach of the Momance River, Haiti; black star is location of 2010 earthquake epicenter; white arrow is flow direction. Old landslides may likely be of prehistoric origin.
Regional distribution of co- and aseismic landslides, and re-activated slope failures. (a) Normalized spatial density of pre-earthquake aseismic landslides within 1-km radius (see text). (b) Spatial density of coseismic landslides. (c) Spatial density of re-activated landslides. (d and e) Fraction of area affected by (d) aseismic and (e) coseismic
Distribution of coseismic deformation, slip, and landslide density. (a) Vertical-deformation signal from InSAR (after Hayes et al., 2010); black circles are mapped coseismic landslides; the black star is the epicenter. (b) Normalized landslide density map (cf. Fig. 4). (c) Rupture model and coseismic slip amplitudes from inversion of InSAR data, field based off-set measurements, and broadband teleseismic body-waveform data (after Hayes et al., 2010). (d) Block diagram of the Léogâne thrust and Enriquillo–Plantain Garden Fault blind rupture. Normalized landslide density superimposed on data by Mercier de Lépinay et al. (2011). Inset block diagram shows proposed fault geometry by Hayes et al., (2010) for Haiti earthquake ruptures. Thick solid lines are surface projections of each fault; PaP: Port-au-Prince.
Along-strike (W–E) distribution of (a) mean coseismic deformation (Hayes et al., 2010), (b) coseismic and re-activated normalized landslide density, (c) mean local relief, and (d)mean hillslope gradient in the uplifted section.N–S distribution of (e) mean coseismic deformation (Hayes et al., 2010), (f) coseismic and re-activated landslide density, (g)mean local relief, and (h) mean hillslope gradient in both uplifted and subsided parts. Inset maps show locations of the swaths. Black lines (c, d, g and h) and shadings are means and±1 σ in 60-m bins. Light and dark grey boxes delimit peaks in normalized landslide density (b), and sub-sections of differing dominant fault geometries in (e). Dashed grey lines are regional means; scale differs between panels (b and f) in coseismic and re-activated landslide density.
Summary of coseismic landslide inventory data from documented reverse or thrust-fault earthquakes. Left panel shows extent of faulting recorded in historical (grey bars) and recent earthquakes (black bars; modified after McCalpin, 2009). Thick and thin black bars are lengths of surface and blind fault ruptures; estimates of surface rupture lengths (grey bars) and maximum coseismic uplift (light grey arrows) from Wells and Coppersmith (1994); lower limits from Bonilla (1988). Maximum coseismic uplift (MCU, dark grey arrows) and surface/blind ruptures: (1)Wenchuan, China, Mw 7.9 (Liu-Zeng et al., 2009); (2) Chi-Chi, Taiwan, Mw 7.6 (Chen et al., 2003); (3) Haiti Mw 7.0 (Hayes et al., 2010); (4) Iwate-Miyagi, Japan, Mw 6.9 (Ohta et al., 2008); (5) Northridge, USA, Mw 6.7 (Shen et al., 1996); and (6) Lorca, Spain, Mw 5.2 (Martinez-Diaz et al., 2012). Right panel shows hanging wall and foot-wall areas affected by coseismic landsliding, and box-and-whisker plots of local relief. Box delimits lower and upper quartiles and median; whiskers are 5th and 95th percentiles; open circles are outliers. Landslide inventory data from Gorum et al. (2011), Liao and Lee (2000), Yagi et al. (2009), Harp and Jibson (1995), and Alfaro et al. (2012); landslide lower limits are from Keefer (1984).
A: Bulk density, magnetic suscep- GC-2 tibility, 234Th (dpm/g), and photo of GC2 recovered from Canal du Sud at 1753 m. The 12 January turbidite contains 5-cm-thick basal bed of black sand and 50 cm of mud above, forming turbidite-homogenite unit. Bulk density decreases upward to nearly seawater values, and magnetic susceptibility signal is higher near base, corresponding to sand rich in magnetic minerals analyzed at 55, 113, and 143 cm (plag—plagioclase; qtz—quartz). Boxes delineate 12 January and older events.
A: Semitransparent lens on Chirp profile is 12 January earthquake-generated turbidite. B: CTD (conductivity, temperature, depth) transmissometer measurements of water column obtained at 1750 m. Anomaly in beam attenuation in lower 600 m is interpreted as sediment plume that has remained in suspension since 12 January.
Tsunami flow depths and runup heights measured along coastlines in the Gulf of Gonaˆve and along Hispaniola’s south coast.
Earthquake Report: East Anatolia fault zone
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
(black lines), the main sutures zones (thick violet or blue lines), the main thrusts in the Hellenides where they have not been reworked by later extension (thin blue lines), the North Cycladic Detachment (NCDS, in red) and its extension in the Simav Detachment (SD), the main metamorphic units and their contacts; AlW: Almyropotamos window; BD: Bey Daglari; CB: Cycladic Basement; CBBT: Cycladic Basement basal thrust; CBS: Cycladic Blueschists; CHSZ: Central Hellenic Shear Zone; CR: Corinth Rift; CRMC: Central Rhodope Metamorphic Complex; GT: Gavrovo–Tripolitza Nappe; KD: Kazdag dome; KeD: Kerdylion Detachment; KKD: Kesebir–Kardamos dome; KT: Kephalonia Transform Fault; LN: Lycian Nappes; LNBT: Lycian Nappes Basal Thrust; MCC: Metamorphic Core Complex; MG: Menderes Grabens; NAT: North Aegean Trough; NCDS: North Cycladic Detachment System; NSZ: Nestos Shear Zone; OlW: Olympos Window; OsW: Ossa Window; OSZ: Ören Shear Zone; Pel.: Peloponnese; ÖU: Ören Unit; PQN: Phyllite–Quartzite Nappe; SiD: Simav Detachment; SRCC: South Rhodope Core Complex; StD: Strymon Detachment; WCDS: West Cycladic Detachment System; ZD: Zaroukla Detachment. B: Seismicity. Earthquakes are taken from the USGS-NEIC database. Colour of symbols gives the depth (blue for shallow depths) and size gives the magnitude (from 4.5 to 7.6).
Seismic Hazard and Seismic Risk
Europe Earthquake Reports
General Overview
Earthquake Reports
Middle East Earthquake Reports
General Overview
Earthquake Reports
Social Media
https://t.co/EuFXnSeqlc#TurkeyEarthquake #elazığdepremi #elazığdadeprem #Elazıg #Malatya #Ergani pic.twitter.com/OXwkvfjDJP
🔗 https://t.co/uJIGwWyfBc — #earthquake #grading in #Turkey#Copernicus #CEMS #RapidMapping #EUCivPro
References:
Basic & General References
Specific References
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Earthquake Report: Puerto Rico!
Since late December, southwestern Puerto Rico has seen a sequence of smaller (M3-5) earthquakes, culminating with the 29 Dec 2019 M 5 which later turned out to be a foreshock (there was also a M 4.7 that was a foreshock to the M5). Then on 6 Jan, there was a M 5.8, which was now the mainshock. Then, on the following day, there was the real mainshock, the M 6.4. Lots of other earthquakes too. The largest aftershock was the M 5.9 on 11 Jan. Below I include some comparisons for the M 6.4 and M 5.9 quakes.
Here is a plot showing the cumulative energy release from this sequence. I used the USGS NEIC earthquake catalog for events M≥0. Time is on the horizontal axis and energy release (in joules) on the vertical axis. For every earthquake, the plot steps up relative to the energy released by that quake.
These earthquakes in Puerto Rico have been deadly and damaging. Many structures there are constructed with soft stories on the ground level (the buildings are uplifted to mitigate hurricane flood hazards). Unfortunately, these soft story structures don’t perform well when subjected to earthquake shaking. Thus, there have been many structure collapses. Luckily, there have been only a few deaths. While we may all agree that having no deaths is best, there could have been more.
The M 6.4 even generated a small tsunami. This was localized and was observed clearly on only one tide gage (The Magueyes Island gage).
Here is the tsunami record, along with a map showing the location of the tide gage in southwestern Puerto Rico. These data are from a site that is my “go-to” website for looking for tsunami in tide gage data. I generally look here first.
USGS Earthquake Event Pages
Here is a screenshot of the forecast updated today (12 Jan 2020). Head to the USGS site to stay up to date.
UPDATE: 2020.02.02 -palindrome day!
Below is my interpretive poster for this earthquake
Background Information
section is shown by a black rectangle on the top map.
Tectonic Strain and Seismic Hazard
Earthquake Shaking Intensity
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.
Surface Deformation from Remote Sensing
Caribbean Earthquake Reports
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Earthquake Reports
Social Media
Thanks to the seismic network of Puerto Rico through IRIS pic.twitter.com/EZoJnIEozu
For the past 11 days, the US territory of Puerto Rico has been shaken by hundreds of earthquakes, culminating in a magnitude 5.8 temblor on Monday and a deadly magnitude 6.4…https://t.co/2FQ9tV8HlU #PuertoRicoEarthquake pic.twitter.com/21iIa6Tz8v
Video desde #Guánica justo que en el momento que un #sismo #réplica termina de colapsar la torre de una iglesia
Via Luis Alberto Románhttps://t.co/OZ2dztAA2x pic.twitter.com/GijFbTnayj
and doi: 0.1785/0120160198 pic.twitter.com/PBgrDlIrk5
(with the usual caveats for near real-time local catalog: changes in catalog completeness and network configuration with time are common when large quakes occur) pic.twitter.com/guhuUodobqUPDATE 2020.01.14
UPDATE 2020.01.25
Maximum magnitudes show a general decreasing tendency since January 07, 2020.
Data from @redsismica of PR! #TemblorPR @DavidBegnaud @adamonzon #EarthquakePR pic.twitter.com/Ag6xErR4My
References:
Basic & General References
Specific References
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Earthquake Report: Gorda plate
The Cascadia subduction zone is formed where the Gorda and Juan de Fuca plates subduct northeastward beneath the North America plate.
The Gorda is losing the battle between the JdF plate to the north and the Pacific plate to the south, both of which are colder, older, and more dense (basically, they form a vise that is squeezing Gorda so much that it deforms internally). This internal deformation results in the formation of left lateral strike slip faults in the southern GP that form on preexisting faults (originally formed at the Gorda rise, where the Gorda plate crust is created).
In the map below, I include a transparent overlay of the magnetic anomaly data from EMAG2 (Meyer et al., 2017). As oceanic crust is formed, it inherits the magnetic field at the time. At different points through time, the magnetic polarity (north vs. south) flips, the north pole becomes the south pole. These changes in polarity can be seen when measuring the magnetic field above oceanic plates. This is one of the fundamental evidences for plate spreading at oceanic spreading ridges (like the Gorda rise).
Regions with magnetic fields aligned like today’s magnetic polarity are colored red in the EMAG2 data, while reversed polarity regions are colored blue. Regions of intermediate magnetic field are colored light purple.
Note that along the Gorda rise, the magnetic anomaly is red, showing that the spreading ridge has a normal polarity, like that of today. Prior to about 780,000 years ago, the polarity was reversed. During the Bruhnes-Matuyama magnetic polarity reversal, the polarity flipped to the way it is today. Note how as one goes away from the Gorda rise (east or west), the magnetic anomaly changes color to blue. At the boundary between red and blue is the Bruhnes-Matuyama magnetic polarity reversal. The earthquakes from today occurred within this blue region, so the oceanic crust is older than about 780,000 years old, probably older than a million years old.
The structures in the Gorda plate in this region are largely inherited from the extensional tectonic and volcanic processes at the Gorda rise. However, the Gorda plate is being pulverized by the surrounding tectonic plates. There are several interpretations about how the plate is deforming and some debate about whether the Gorda plate is even behaving like a plate. These normal fault (extensional) structures have been reactivating as left-lateral strike-slip faults as a result of this deformation. This region is called the Mendocino deformation zone (a.k.a. the Triangle of Doom).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.
Earthquake Shaking Intensity
Some Relevant Discussion and Figures
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.
Stress Triggering
[1993] model for the 1992 Cape Mendocino earthquake (J). Calculation depth is 5 km. The numbered brackets are groups of aftershocks from Hill et al. [1990].
Cascadia subduction zone
General Overview
Earthquake Reports
Gorda plate
Blanco transform fault
Mendocino fault
Mendocino triple junction
North America plate
Explorer plate
Uncertain
References:
Basic & General References
Specific References
Return to the Earthquake Reports page.
Earthquake Report: 2010 Haiti M 7.0
https://earthquake.usgs.gov/earthquakes/eventpage/usp000h60h/executive
Here I review some of the earthquake related materials from this temblor.
The M 7 earthquake happened on a strike-slip fault system that accommodates relative plate motion between the North America and Caribbean plates. There is a history and prehistory of earthquakes on this fault system.
This event was quite deadly. Here is a comparison of this earthquake relative to other earthquakes (Billham, 2010).
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.
Resources Canada. b, Position time series at station DFRT (orange arrow labelled on a) showing four pre-earthquake measurement epochs and the post-earthquake epoch. Note the steady interseismic strain accumulation rate and the sudden coseismic displacement.
Earthquake Stress Triggering
thrust). Major cities are noted by green circles.
Earthquake Humanitarian Impact
Earthquake Shaking Intensity
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.
landslides per 0.01° latitude; circles are individual landslide locations scaled by area (see legend in panel g). Thin black dashed lines are areas affected by the landslides; thick black dashed lines are mean local relief of coseismically uplifted and subsided areas. (f and g) Histograms of (f) point density [km−2] and (g) rate [%] of re-activated landslides for 0.01° latitude bins; PaP: Port-au-Prince; PG: Petit Goave.
Earthquake Triggered Turbidity Currents
Earthquake Triggered Tsunami
Caribbean Earthquakes
General Overview
Earthquake Reports
Social Media
References:
Basic & General References
Specific References
during the 2010 Haiti earthquake in Nature Geoscience, http://www.nature.com/doifinder/10.1038/ngeo992Return to the Earthquake Reports page.