Earthquake Report: M 7.0 northern California

My Experience for this Earthquake

I was attending a meeting for work where we were discussing the ongoing development of a tool that we (the California Tsunami Program – the CA Governor’s Office of Emergency Services and the California Geological Survey) use with the National Weather Service to provide recommendations to first responders (e.g., those with authority to evacuate the public) on what level of response they might consider.

We use this tool during an annual exercise with each of the 20 local counties where we walk through the steps of a tsunami event.

During this meeting, I got an Earthquake Early Warning alert on my mobile phone. A moment later, i felt the P-wave of the earthquake (it comes first because it travels faster than the S-wave).

I thought, time to drop, cover, and hold on. Then the stronger S-wave hit and i was definitely headed for the floor. i informed my colleagues and they started getting their EEW notices. They were in central-northern CA.

The shaking lessened but continued for a long time. Maybe more than 20 seconds.

Needless to say, the meeting was over as it was time for all of us to get to work with tsunami and earthquake event response. CGS leadership contacted me to discuss a meeting we would hold to consider the scope of our field response. We would later decide to send some engineering geologists into the field to make observations of perishable features left by the earthquake.

https://earthquake.usgs.gov/earthquakes/eventpage/nc75095651/executive

My power was out (planned outage) so i continued on my laptop and cellular hotspot to generate an Earthquake Quick Report that CGS provides Cal OES. Then i grabbed some snacks, my laptops, water bottle, and jumped in my truck (in case i needed to head to the field) and drove to my office in the National Weather Service building on Woodley Island.

There is redundant power and internet there, where i would need to be able to attend virtual meetings for the rest of the day. Troy Nicolini and Ryan Aylward (NWS tsunami team members in Eureka) have been key tsunami partners with the Redwood Coast Tsunami Work Group for many years.

I share space with a colleague (Todd Becker) from Cal OES and a colleague (Sherry Constancio) from the Dept. of Water Resources. We have all been working with the RCTWG for decades. So, it is especially good that Todd and i are in the same office during a tsunami event.

I won’t go into all the details of event response. But we (the CTP) participated in calls with the National Tsunami Warning Center (the authoritative organization for tsunami alerts on the US/Canada west coast).

The NTWC placed some of the west coast into a tsunami “Warning.” The different tsunami alert levels (displayed in graphic below) are explained here.

The NTWC follows operating procedures and these procedures are in a constant flux towards improving them. We learn something new during each tsunami event and the NTWC incorporates this new knowledge into their improved procedures. They are very receptive to feedback!

We typically have hourly calls with the NTWC and hourly calls (on the opposite part of the hour) with coastal counties. During the first call with the NTWC, the Tsunami Warning was cancelled. We did not need to hold a call with the local counties.

I went to get lunch (wanted more than roasted nuts for the long day) and both the coop and the natural foods stores were closed (they are both in the Tsunami Hazard Area, THA). Find out where the THA is on your part of the California coastline here.

More meetings, following up on communications efforts, and planning for the rest of the event response.

Tectonic Background for this Earthquake

Today’s M 7.0 earthquake has a strike-slip mechanism. Because of the location along the Mendocino fault (MF, a right-lateral strike-slip earthquake fault) and the aftershocks, it is straightforward to interpret this as a right-lateral strike-slip earthquake.

Yesterday morning (early, i remember) there were a couple M 4+ earthquakes also along the MF. They seemed to be east of the last M7+ MF earthquake, a M 7.1 earthquake on 1 September 1994. But upon further inspection, these earthquakes were west of the 1994 earthquake. it is always better to have a second or third look at things.

The MF is a plate boundary fault between the Pacific plate to the south and the Gorda plate (part of the Juan de Fuca plate system).

To the north, the Gorda oceanic plate dives down into the Earth, beneath the North America continental plate. Where these plates meet is called the Cascadia subduction zone, a convergent plate boundary where plates move towards each other.

The Cascadia subduction zone (CSZ) has never had an historic earthquake but there is a history of prehistoric earthquakes (going back about 10,000 years in places). The CSZ is a source of tsunami for the northeast Pacific, from northern California, through Oregon and Washington, up to Canada.

Prehistoric CSZ tsunami have even travelled across the Pacific Basin to inundate in places like Japan!

The MF, that forms the southern boundary of the Gorda plate, follows the Gorda plate beneath North America. Historic seismicity shows where the southern edge of the Gorda plate (aka the MF) is located.

There was a MF earthquake in 1994 that had an epicenter about 50 km to the west of today’s M 7.0. Aftershocks from the 1994 earthquake spanned across the shoreline.

Today’s M 7.0 earthquake spanned the eastern part of the 1994 rupture. Perhaps the 1994 earthquake had less slip in this eastern part of the fault?

Below I explore the ground shaking and ground failure models from the USGS. All the data that i plot in this report is freely available from the USGS.

[NOTE] Mendocino fault:

Earlier studies, from the late 20th century (e.g., Jachens and Griscomb, 1983) used geophysical data to locate the southern edge of the Gorda plate. But there were just as many papers that suggested it was not as far south as the Jachens and Griscomb model.

While there was strong evidence for both interpretations (in the 1980s), most models of the CSZ chose the southern edge, the Jachens and Griscomb southern edge.

It is clear, however, that Jachens and Griscomb are most likely incorrect. There must be other explanations for their crude geophysical observations. (these types of observations are indirect and difficult to interpret in an unequivocal way).

Wwe are trying to get all new updated slab models to abandon the Jachens and Griscom model. All earthquake catalogs with relocated seismicity show a knife edge southern edge of the Gorda plate.

Earthquake Triggering

Perhaps one of the most common questions about earthquakes of most any magnitude is, “what are the chances that this earthquake will cause an earthquake on a different fault?”

Or, “will this earthquake cause an earthquake on the Cascadia subduction zone?”

I have addressed this question for earthquakes along the Blanco transform fault. a right-lateral strike-slip fault to the north of the Gorda plate.

When earthquake faults slip, the surrounding crust and faults change shape and this causes areas of the faults to get imparted increased or decreased amounts of stress. If these faults are almost ready to slip and the change of stress is increased sufficiently, those source earthquakes may trigger earthquakes on the receiver fault (the one with increased stress). This is termed “static coulomb stress triggering.”

Typically the maximum distance from an earthquake that these stress changes can trigger an earthquake is about twice the length of the source earthquake.

If we use data from historic earthquakes to correlate earthquake fault slip length to magnitude, we can estimate the length of the Mendocino fault that slipped during the M 7.0 temblor (Wells and Coppersmith, 1994).

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.

* note, i corrected this caption by changing the word “relationships” to “relations.”
(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.

We don’t really know what the SRL for the M 7.0, but using these empirical relations, the length of the M 7.0 fault is probably about 50 km (which matches the USGS finite fault slip model). So, the distance that the M 7.0 could probably trigger another quake is limited to 80 km or so. The part of the megathrust that might slip during an earthquake is within this distance.

To give us an idea about this stress triggering stuff, below is a figure from Rollins and Stein (2010). This figure shows the results from their model. This model shows the change in stress imparted upon the crust surrounding the 1994 earthquake. Note that the Mendocino fault to the east of the 1994 earthquake had an increase in stress following the 1994 earthquake. Imagine that this region of increased stress is similarly located east of the 5 December 2024 M 7.0 earthquake, and may extend beneath the North America plate.

The red areas show areas of increased stress, blue areas show decreased stress. This is based on a left-lateral strike-slip fault (so a right-lateral quake would produce changes in stress the opposite as this, red regions would be blue and blue regions would be red, generally).

Coulomb stress changes imparted by our models of (a) a bilateral rupture and (b) a unilateral eastward rupture for the 1994 Mw = 7.0 Mendocino Fault Zone earthquake to the epicenters of the 1995 Mw = 6.6 southern Gorda zone earthquake (N) and the 2000 Mw = 5.9 Mendocino Fault Zone earthquake (O). Calculation depth is 5 km.(con’t)

While earthquake faults are unpredictable, it is possible that the M 7.0 earthquake increased the stress along the faults to the east (and west) of the rupture. This includes the faults in the North America plate as well as the Cascadia subduction zone. In the aftershocks interpretive poster below, I label some of these crustal faults capable of generating earthquakes.

We won’t know until that happens. Thus it is smartest if those who are in Earthquake Country learn how to be Earthquake Prepared. Here are two resources:

Living on Shaky Ground from the Redwood Coast Tsunami Workgroup
Seven Steps to Earthquake Safety from the Earthquake Country Alliance

To investigate this, i overlaid the Rollins and Stein (2010) static coulomb stress modeling results for the 1994 earthquake. The 2024 M 7.0 earthquake is different in several ways. So, this is just a crude comparison.

In the map below I show an inset in the lower right that shows the Rollins and Stein (2010) figure 4 A overlain on the 1994 rupture, the earthquake that they analyzed.

In the main map, i shifted their figure to align with the 2024 M 7.0 epicenter. We can see that the increased stress regions extend towards the Cascadia megathrust. Also, we can see increased stress for left lateral strike-slip faults in the Gorda plate (like the 1980, 1991, and 2005 earthquakes shown on the map).

UPDATE: Temblor has published the results from their specific analysis for this earthquake (which is far better than my crude comparison): https://temblor.net/earthquake-insights/did-2024-magnitude-7-0-cape-mendocino-earthquake-trigger-aftershocks-on-san-andreas-16506/

Tsunami?

I will write more about this observation. There was a tsunami recorded on the Arena Cove tide gage.

There does not appear to be a tsunami recorded at the North Spit tide gage. But there is a long period (1 hour-ish) wave recorded on that gage. Plus there are observations that the Arcata Bay drained and filled up about 3 times on a uith a 30 minute period. We are working on this. Was it a seiche? (generated by the interaction between seismic surface waves and the geometry of the bay (causing resonance).

Here is the plot from the Arena Cove tide gage.

The water levels before the tsunami show considerable background noise. So, it is difficult to know how much of the wave size is attributable solely to the tsunami.

The official wave size is 9 cm. But i get different values.

Key Take Away Lessons

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 1924-2024 with magnitudes M ≥ 3.0 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.

I include some inset figures. Some of the same figures are located in different places on the larger scale map below.

In the upper left corner is a map showing the plate tectonic boundaries (from the GEM).
In the upper right corner is a map that shows the M 6.8 earthquake intensity using the modified Mercalli intensity scale. Earthquake intensity is a measure of how strongly the Earth shakes during an earthquake, so gets smaller the further away one is from the earthquake epicenter. The map colors represent a model of what the intensity may be. The USGS has a system called “Did You Feel It?” (DYFI) where people enter their observations from the earthquake and the USGS calculates what the intensity was for that person. The dots with yellow labels show what people actually felt in those different locations.
To the left of the intensity map is a plot that shows the same intensity (both modeled and reported) data as displayed on the map. Note how the intensity gets smaller with distance from the earthquake.
In the upper right corner are two maps showing the possibility of earthquake induced liquefaction for these two earthquakes. I discuss these phenomena in more detail later in the report.
In the upper left center is a map that shows the displacement of benchmarks as measured by GNSS (used to be called GPS) observations. The displacement is represented by an arrow. The blue arrows show the direction and distance each benchmark moved (the arrow is called a vector). The USGS uses observations from seismometers and from these displacements to model the amount that the fault slipped during the earthquake. The red vectors show how their slip model generates displacement at these benchmark locations. The model is imperfect as we see that the red and blue vectors are all a little different (though they are all very close).
In the lower left center is the USGS finite fault slip model. This rectangle represents the fault that slipped during the earthquake (see the location of this fault model on the map, the orange line). The color represents the amount of fault slip in different parts of the fault. I used the USGS coordinates to plot the fault slip model on the map, but it is clear that this is incorrect. I will try to update this manually later.

Here is the map with a month’s seismicity plotted.
Note that i outlined the regions of the aftershocks for both the 1994 (in green) and the 2024 (in orange/white) earthquake sequence. This interpretation is consistent with the figure from Dengler showing mechanisms for the earthquakes in 1994 (see below).
The rupture length for the 1994 earthquake was much longer than that for the 2024 earthquake. Why do you think this is?

Here is the map with 2.5 day’s worth of seismicity plotted.

Other Report Pages

Earthquake Insights

Here is a video from Thomas Dunklin, a geologist that lives in the Petrolia area who has felt and observed more earthquakes in the region than most people.

Shaking Intensity

Here is a figure that shows a more detailed comparison between the modeled intensity and the reported intensity. Both data use the same color scale, the Modified Mercalli Intensity Scale (MMI). More about this can be found here. The colors and contours on the map are results from the USGS modeled intensity. The DYFI data are plotted as colored dots (color = MMI, diameter = number of reports).
In the upper panel is the USGS Did You Feel It reports map, showing reports as colored dots using the MMI color scale. Underlain on this map are colored areas showing the USGS modeled estimate for shaking intensity (MMI scale).
In the lower panel is a plot showing MMI intensity (vertical axis) relative to distance from the earthquake (horizontal axis). The models are represented by the green and orange lines. The DYFI data are plotted as light blue dots. The mean and median (different types of “average”) are plotted as orange and purple dots. Note how well the reports fit the green line (the model that represents how MMI works based on quakes in California).
Below the map and the lower plot is the USGS MMI Intensity scale, which lists the level of damage for each level of intensity, along with approximate measures of how strongly the ground shakes at these intensities, showing levels in acceleration (Peak Ground Acceleration, PGA) and velocity (Peak Ground Velocity, PGV).

Shaking Intensity and Potential for Ground Failure

Below are a series of maps that show the shaking intensity and potential for landslides and liquefaction. These are all USGS data products.

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.

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.

Below is the liquefaction susceptibility and landslide probability map (Jessee et al., 2017; Zhu et al., 2017). Please head over to that report for more information about the USGS Ground Failure products (landslides and liquefaction). Basically, earthquakes shake the ground and this ground shaking can cause landslides. We can see that there is a low probability for landslides. However, we have already seen photographic evidence for landslides and the lower limit for earthquake triggered landslides is magnitude M 5.5 (from Keefer 1984)
I use the same color scheme that the USGS uses on their website. Note how the areas that are more likely to have experienced earthquake induced liquefaction are in the valleys. Learn more about how the USGS prepares these model results here.

Some Relevant Discussion and Figures

Here is a map of the Cascadia subduction zone, modified from Nelson et al. (2006). The Juan de Fuca and Gorda plates subduct norteastwardly beneath the North America plate at rates ranging from 29- to 45-mm/yr. Sites where evidence of past earthquakes (paleoseismology) are denoted by white dots. Where there is also evidence for past CSZ tsunami, there are black dots. These paleoseismology sites are labeled (e.g. Humboldt Bay). Some submarine paleoseismology core sites are also shown as grey dots. The two main spreading ridges are not labeled, but the northern one is the Juan de Fuca ridge (where oceanic crust is formed for the Juan de Fuca plate) and the southern one is the Gorda rise (where the oceanic crust is formed for the Gorda plate).

Here is a version of the CSZ cross section alone (Plafker, 1972). This shows two parts of the earthquake cycle: the interseismic part (between earthquakes) and the coseismic part (during earthquakes). Regions that experience uplift during the interseismic period tend to experience subsidence during the coseismic period.

This poster includes seismicity from the past ~5 decades, for temblors M > 3.0. I also include the map and cross section as explained above. On the left is a map that shows the possible shaking intensity from a future CSZ earthquake.

More about the materials on this poster can be found on this page.

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.

Hemphill-Haley, E., 1995. Diatom evidence for earthquake-induced subsidence and tsunami 300 yr ago in southern coastal Washington in GSA Bulletin, v. 107, p. 367-378.
Nelson, A.R., Shennan, I., and Long, A.J., 1996. Identifying coseismic subsidence in tidal-wetland stratigraphic sequences at the Cascadia subduction zone of western North America in Journal of Geophysical Research, v. 101, p. 6115-6135.
Atwater, B.F. and Hemphill-Haley, E., 1997. Recurrence Intervals for Great Earthquakes of the Past 3,500 Years at Northeastern Willapa Bay, Washington in U.S. Geological Survey Professional Paper 1576, Washington D.C., 119 pp.

This figure shows how a subduction zone deforms between (interseismic) and during (coseismic) earthquakes. We also can see how a subduction zone generates a tsunami. Atwater et al., 2005.

Here is an animation produced by the folks at Cal Tech following the 2004 Sumatra-Andaman subduction zone earthquake. I have several posts about that earthquake here and here. One may learn more about this animation, as well as download this animation here.

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.

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.

Here is a link to the embedded video below, showing the week-long seismicity in April 1992.

This is the map used in the animation below. Earthquake epicenters are plotted (some with USGS moment tensors) for this region from 1917-2017 with M ≥ 6.5. I labeled the plates and shaded their general location in different colors.
I include some inset maps.

In the upper right corner is a map of the Cascadia subduction zone (Chaytor et al., 2004; Nelson et al., 2004).
In the upper left corner is a map from Rollins and Stein (2010). They plot epicenters and fault lines involved in earthquakes between 1976 and 2010.

Here is a map from Rollins and Stein, showing their interpretations of different historic earthquakes in the region. This was published in response to the Januray 2010 Gorda plate earthquake. The faults are from Chaytor et al. (2004).

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.

Here is a large scale map of the 1994 earthquake swarm. The mainshock epicenter is a black star and epicenters are denoted as white circles.

Here is a plot of focal mechanisms from the Dengler et al. (1995) paper in California Geology.

In this map below, I label a number of other significant earthquakes in this Mendocino triple junction region. Another historic right-lateral earthquake on the Mendocino fault system was in 1994. There was a series of earthquakes possibly along the easternmost section of the Mendocino fault system in late January 2015, here is my post about that earthquake series.

Here is a map from Chaytor et al. (2004) that shows some details of the faulting in the region. The moment tensor (at the moment i write this) shows a north-south striking fault with a reverse or thrust faulting mechanism. While this region of faulting is dominated by strike slip faults (and most all prior earthquake moment tensors showed strike slip earthquakes), when strike slip faults bend, they can create compression (transpression) and extension (transtension). This transpressive or transtentional deformation may produce thrust/reverse earthquakes or normal fault earthquakes, respectively. The transverse ranges north of Los Angeles are an example of uplift/transpression due to the bend in the San Andreas fault in that region.

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.

These are the models for tectonic deformation within the Gorda plate as presented by Jason Chaytor in 2004.

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.

Cascadia subduction zone

General Overview

1700.09.26 M 9.0 Cascadia’s 315th Anniversary 2015.01.26
1700.09.26 M 9.0 Cascadia’s 316th Anniversary 2016.01.26 updated in 2017 and 2018
1992.04.25 M 7.2 Cape Mendocino 25 year remembrance
1992.04.25 M 7.2 Cape Mendocino 25 Year Remembrance Event Page
Earthquake Information about the CSZ 2015.10.08

Earthquake Reports

North America plate

2024.10.24 M 4.4 NAP

2016.11.02 M 3.6 Oregon
2016.01.07 M 4.2 NAP(?)

2015.10.29 M 3.4 Bayside

Explorer plate

Uncertain

2017.06.11 M 3.5 Gorda or NAP?

2016.07.21 M 4.7 Gorda or NAP? p-1
2016.07.21 M 4.7 Gorda or NAP? p-2

Social Media

References:

Basic & General References

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
Storchak, D. A., D. Di Giacomo, I. Bondár, E. R. Engdahl, J. Harris, W. H. K. Lee, A. Villaseñor, and P. Bormann (2013), Public release of the ISC-GEM global instrumental earthquake catalogue (1900–2009), Seismol. Res. Lett., 84(5), 810–815, doi:10.1785/0220130034.
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Specific References

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Chaytor, J.D., Goldfinger, C., Dziak, R.P., and Fox, C.G., 2004. Active deformation of the Gorda plate: Constraining deformation models with new geophysical data: Geology v. 32, p. 353-356.
Dengler, L.A., Moley, K.M., McPherson, R.C., Pasyanos, M., Dewey, J.W., and Murray, M., 1995. The September 1, 1994 Mendocino Fault Earthquake, California Geology, Marc/April 1995, p. 43-53.
Geist, E.L. and Andrews D.J., 2000. Slip rates on San Francisco Bay area faults from anelastic deformation of the continental lithosphere, Journal of Geophysical Research, v. 105, no. B11, p. 25,543-25,552.
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