Earthquake Report: M 4.9 Barstow, California

Well, as I was driving to town to pay a bill (as we all do), I got my alert of a M 4.5 (later changed to 4.9) earthquake in southern California.

I immediately drove back to the office to prepare a report for my organization. We have set up a webform for preparing these reports. So, instead of spending about an hour on these, they only take about 10 minutes.

I thought about how a M 4.9 is not a large magnitude and it happened in an area with a low density population (in the Mojave Desert). So I probably would not do an Earthquake Report for earthjay.

There was a magnitude M 4.9 earthquake east of Barstow, southern California. The tectonics of this region is mostly controlled by the Pacific-North America plate boundary.

https://earthquake.usgs.gov/earthquakes/eventpage/ci40675215/executive

The main fault related to this plate boundary is the San Andreas fault, where the Pacific plate on the west moves north relative to the North America plate on the east.

In southeastern California, there are a bunch of roughly North-South oriented faults that are all right-lateral strike-slip faults (just like the San Andreas fault). These faults in the Mojave Desert are called the Eastern California shear zone (ECSZ). The ECSZ trends from the bend in the San Andreas to the south, northwards, to the east side of the Sierra Nevada, via a tectonic system called the Walker Lane.

The epicenter (the location of the earthquake on a map) showed that this earthquake happened near the Calico fault. The Calico fault is a right-lateral strike-slip fault, part of the Eastern California shear zone.

These types of faults are where the Earth’s crust moves side by side. Right-lateral means that when one is standing on one side of the fault, the other side of the fault moves to the right.

There is also a major fault system called the Garlock fault (GF). The GF is a roughly East-West oriented left-lateral strike-slip fault. Left-lateral means that when one is standing on one side of the fault, the other side of the fault moves to the left.

The earthquake mechanism (focal mechanism and moment tensor) showed that the M 4.9 earthquake could be a North-South oriented (“striking”) right-lateral strike-slip fault or an East-West oriented left-lateral strike-slip fault.

Given the proximity to the Calico fault (CF), I originally thought this earthquake was on the Calico fault (or nearby fault related to the Calico fault).

But, last night my friend Paul Hancock emailed me with some screenshots of the USGS earthquake page.

Paul noticed that the mainshock and aftershocks aligned with an approximately East-West trend. This was interesting. He asked me what I thought.

I told him that, presuming that the earthquake locations are good (they probably are), then this may be a cross fault. A cross fault is a fault that is about perpendicular (+-) to the main fault system and may connect two other strike-slip faults.

Then I looked at the USGS Quaternary fault and fold database and the CGS fault activity map. There is actually an East-West striking (oriented) strike-slip fault that points right to the M 4.9 earthquake.

The Manix fault is a left-lateral strike-slip fault, similar orientation and fault type as the Garlock fault.

Here is a photo showing the Manix fault (photo credit: Andrew Cyr, USGS).


This made me think of the 2007 Pacific Cell Friends of the Pleistocene field trip, where we reviewed the ongoing research into the Pleistocene (from 2.56 million years ago until about 12 thousand years ago) sedimentary history of the Lake Manix Basin.

Then I looked at the recent papers by people like Marith Reheis and Mike Oskin (as well as some older papers from Richter and Doser). These papers all have different fault maps that show how these faults are quite complex.

Though, after I plotted up the earthquakes, and used the USGS QFFDB, I am sticking with the hypothesis that this M 4.9 earthquake sequence is a left-lateral strike-slip earthquake on a fault related to the Manix fault system.

This is an interesting earthquake sequence, well worthy of an Earthquake Report.

UPDATE

My friend Ken Hudnut sent me a message suggesting I modify this Earthquake Report a bit.

While I wrote that these faults strike in the North-South and East-West directions, they actually strike a little differently.

Most of the San Andreas oriented faults strike north-northwest/south-southeast (N-NW/S-SE) and most of the faults that are similar to the Garlock fault strike east-northeast/west-southwest (E-NE/S-SW).

The orientation of the relative motion between the Pacific and North America plates is close to N35W (35 degrees counterclockwise from North) as determined by DeMets and Merkouriev (2016).

Here is a figure from DeMets and Merkouriev (2016) that shows the relative plate motion rates through time. See the lower panel and look at the blue line, how it plots at 35 degrees.


Pacific–North America interval rates (a) and slip directions (b) since 8 Ma estimated at 36.0◦N, 120.6◦W along the San Andreas Fault of central California (star in insetmap). The best-fitting interval velocitieswere derived from finite rotations in Table 4 as described in Section 4.3.1. Other sources for the interval velocities are listed in the legend. Horizontal dashed lines show the time intervals spanned by the best-fitting interval rates and directions. Where shown, the uncertainties are 1σ and are propagated from the angular velocity covariances. Some uncertainties are omitted for clarity.

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 that shows the earthquake faults and historic earthquake locations (epicenters) in the western US. Historic earthquake fault ruptures are mapped as red lines and labeled with their year and magnitude.
  • In the lower right corner is a map that shows a comparison of the US Geological Survey Shakemap (a model of how strong the ground might shake during the M 5.8 earthquake) and results from online web surveys from peoples’ real observations (i.e. “Did You Feel It?” reports. The colored lines show the boundary between different levels of intensity using the Modified Mercalli Intensity (NNI) scale. The areas are colored relative to the DYFI reports, using the same MMI scale and colors shown on the legend).
  • In the upper right corner is a map that shows the aftershocks relative to the USGS Quaternary Active Fault and Fold Database.
  • Here is the map with a month’s seismicity plotted.


Other Report Pages

Some Relevant Discussion and Figures

    • Here is a figure from Rinke et al. (2012) that shows the global and regional tectonics here. I include the figure captions below as blockquotes. The first map shows the plate boundary scale tectonic regions. This is a generalized map (e.g. don’t pay attention to where the San Andreas and Cascadia faults are located).


      • Simplified tectonic map of the western U.S. Cordillera showing the modern plate boundaries and tectonic provinces. Basin and Range Province is in medium gray; Central Nevada seismic belt (CNSB), eastern California shear zone (ECSZ), Intermountain seismic belt (ISB), and Walker Lane belt (WLB) are in light gray; Mina deflection (MD) is in dark gray.

    • Here is the Amos et al. (2013) plate tectonic map. Check out the location of the historic surface rupturing earthquakes. Their figure caption is below (as for other figures here).


      • Overview of active faults and regional topography of the Eastern California shear zone (ECSZ) and southern Walker Lane belt. Labeled faults are abbreviated as follows: ALF—Airport Lake fault, BF—Blackwater fault, GF—Garlock fault, KCF—Kern Canyon fault, LLF—Little Lake fault, OVF—Owens Valley fault, SNFF—Sierra Nevada frontal fault. OL—Owens Lake, IWV—Indian Wells Valley. Major historical earthquake surface ruptures in the Eastern California shear zone and Walker Lane belt are outlined in white, with stars denoting epicentral locations: OV—1872 Owens Valley, L—Landers 1992, HM—1999 Hector Mine. Active fault traces are taken from the U.S. Geological Survey Quaternary fault and fold database, with the exception of the Kern Canyon fault, taken from Brossy et al. (2012).

    • This map extends a little farther to the east (Frankel et al., 2008). This map shows nicely how the Sierra Nevada and Owens Valley faults (the Pacific-North America plate boundary) and Eastern California Shear Zone, aka ECSZ (the maps south of the Garlock fault, 35.5N°) interact with east-west trending left-lateral strike-slip faults like the Garlock fault. The ’92 Landers and ’99 Hector Mine Earthquakes are on faults in the ECSZ.


      • Shaded relief index map of Quaternary faults, roads, towns, and fi eld trip stops in the eastern California shear zone. Most faults are from the U.S. Geological Survey Quaternary fault and fold database (http://earthquake.usgs.gov/regional/qfaults). Arrows indicate relative fault motion for strike slip faults. Bar and circle indicates the hanging wall of normal faults. Field trip stop location numbers are tied to site descriptions in the fi eld guide section. AHF—Ash Hill fault; ALF—Airport Lake fault; B—Bishop; BF—Blackwater fault; BLF—Bicycle Lake fault; BM—Black Mountains; BP—Big Pine; Br—Baker; Bw—Barstow; By—Beatty; CA—California; CF—Cady fault; CLF—Coyote Lake fault; CoF—Calico fault; CRF—Camp Rock fault; DSF—Deep Springs fault; DV-FLVF—Death Valley–Fish Lake Valley fault; EPF—Emigrant Peak fault; EV— Eureka Valley; FIF—Fort Irwin fault; FM—Funeral Mountains; GF—Garlock fault; GFL—Goldstone Lake fault; GM—Grapevine Mountains; HF—Helendale fault; HLF—Harper Lake fault; HMSVF—Hunter Mountain–Saline Valley fault; I—Independence; LF—Lenwood fault; LLF— Lavic Lake fault; LoF—Lockhart fault; LP—Lone Pine; LuF—Ludlow fault; LV—Las Vegas; M—Mojave; MF—Manix fault; NV—Nevada; O—Olancha; OL—Owens Lake; OVF—Owens Valley fault; P—Pahrump; PF—Pisgah fault; PV—Panamint Valley; PVF—Panamint Valley fault; R—Ridgecrest; S—Shoshone; SAF—San Andreas fault; SDVF—southern Death Valley fault; SLF—Stateline fault; SPLM—Silver Peak–Lone Mountain extensional complex; SNF—Sierra Nevada frontal fault; SP—Silver Peak Range; T—Tonopah; TF—Tiefort Mountain fault; TMF—Tin Mountain fault; TPF—Towne Pass fault; WMF—White Mountains fault; YM—Yucca Mountain.

    • Here is a great overview map of the faults in the region from Oskin et al. (2008). Their paper is about their research to quantify the tectonic loading of faults in the Eastern California shear zone. Note that they use about 12 mm per year of Pacific-North America relative plate motion across this region.


      • A: Index map of southwest North America showing geodetic provinces from Bennett et al. (2003) and location of Mojave block. Velocities of geodetically stable regions are shown relative to Colorado Plateau. ECSZ—eastern California shear zone in Mojave block. Shear zone continues northward into western Great Basin province. GF—Garlock fault. B: Index map of the Mojave block with active faults and locations of recent earthquake ruptures. Circles show localities of slip-rate measurements that sum to ≤6.2 ± 1.9 mm/yr across the ECSZ. GPS—global positioning system.

    • Here is another good overview map, showing the faults for which Petersen and Wesnousky (1994) reviewed slip rates in that publication. They present an excellent review of all slip rate and paleoseismic investigations at the time that paper was published.


      • Map showing sites of slip rate studies in southern California for the San Andreas (SAI-14), San Jacinto (SJI-13), Elsinore-Whittier (El-8), Newport- Inglewood (N1-3), Palos Verdes (N4-6), Rose Canyon (N7), Transverse Ranges (T1-50), Mojave (MI-6), and Garlock (G1-9) faults.

    • Oskin and Iriondo studied the Blackwater fault, the right-lateral strike-slip fault system that extends from the south into the region of the Ridgecrest Earthquake Sequence. The Blackwater fault is connected to the south with the Calico fault (a fault between the 1992 and 1999 earthquakes). This appears to be the major Eastern California Shear zone fault that extends towards the Airport Valley and Little Lake faults (which ruptured during the Ridgecrest Earthquake Sequence).


      • A: Index map of Pacific–North America plate boundary through southwest North America. Principal faults are shown as thick black lines. Tectonically stable areas are outlined by dotted lines. Walker Lane and Eastern California shear zone, shown as dark gray band encompassing network of active faults, together absorb 9%–23% of total plate boundary shear (Dixon et al., 2000; Dokka and Travis, 1990a). JDF—Juan de Fuca; MTJ— Mendocino triple junction. B: Index map of Eastern California shear zone showing fault slip rates (in parentheses, mm/yr) determined by paleoseismic studies (Klinger and Piety, 2000; Lee et al., 2001; McGill and Sieh, 1993; Rockwell et al., 2000; Zhang et al., 1990). Heavy dark gray lines outline historic earthquake ruptures (Beanland and Clark, 1994; Sieh et al., 1993; Treiman et al., 2002). Heavy, medium gray band highlights Blackwater–Calico fault system. Light gray band surrounding Blackwater fault and passing north of Garlock fault is zone of localized 1.2 6 0.5 mm/yr strain accumulation documented by radar interferometry (Peltzer et al., 2001). C: Neotectonic map of Blackwater fault, showing type and orientation of fault line scarps with ticks on downthrown side. Dark patterned areas are lava flows cut by Blackwater fault (Dibblee, 1968, 1967; Smith, 1964)

    • Peltzer et al. (2001) evaluate the amount of tectonic strain that has accumulated over time (see geodesy section to learn more about strain). First I present their tectonic map.


      • Tectonic map of southern California. Solid lines are active faults (Jennings, 1975). Yellow dots are relocated earthquakes between 1981 and 2000 (Hauksson, 2000). Dashed-line box is area covered by Earth Resource Satellite (ERS) data used in this study. White dashed line shows location of concentrated shear observed in synthetic aperture radar (SAR) data. Black stars indicate epicenters of recent earthquakes: OV—1872 Owens Valley, JT—1992 Joshua Tree, L—1992 Landers, BB—1992 Big Bear, N—1994 Northridge, RC—1994 and 1995 Ridgecrest, HM—1999 Hector Mine. Heavy solid lines depict surface ruptures of Landers (Sieh et al., 1993), Hector Mine (U.S. Geological Survey and California Division of Mines and
      Geology, 2000; Peltzer et al., 2001), and Owens Valley (Beanland and Clark, 1994; only southern half of rupture is shown) earthquakes. Black dots and arrows show locations and observed velocities of 11 stations of Yucca GPS array (Gan et al., 2000).
      * Faults are listed in the paper

  • Here is a map from Oskin et al. (2007) that shows the main faults and their senses of motion. Their paper is about the slip rate of the Calico fault.
  • Note that the Calico fault is the main fault between the Pisgah and Camp Rock faults that ruptured in 1999 and 1992 respectively.
  • Here is a California Geological Survey website for the 1992 Landers Earthquake.
  • Also note how the Calico fault trends towards the Blackwater fault. This is one fault that we suspect may host an earthquake to link the 1992/1999 earthquakes with the 2019 Ridgecrest earthquake sequence to the north.


    • (a) Index map of the Pacific–North America plate boundary through southwestern North America. Principal faults are shown as thick black lines. Walker Lane and Eastern California Shear Zone, shown as dark gray band encompassing network of active faults, together absorb 9–23% of total Pacific–North America plate boundary shear [Dixon et al., 2000; Dokka and Travis, 1990b]. JDF, Juan de Fuca; MTJ, Mendocino triple junction. Area of Figure 1b enclosed by dashed line. (b) Index map of Eastern California Shear Zone showing fault slip rates (in parentheses, mm/yr) determined from paleoseismic studies [Bryan and Rockwell, 1995; Cadena et al., 2004; Padgett and Rockwell, 1993; Rubin and Sieh, 1997], offset alluvial terraces and fans [McGill and Sieh, 1993; Weldon and Sieh, 1985; Zhang et al., 1990], and offset basalt flows [Hart et al., 1988; Oskin and Iriondo, 2004]. Dark gray bands outline historic earthquake ruptures [Sieh et al., 1993; Treiman et al., 2002]. Medium gray band highlights Calico-Blackwater fault system.

  • This map shows more details about the faults in the region. The Manix fault and Calico fault come near to meeting each other in the upper center part of the upper map (A).
  • See how the Calico fault turns into a reverse fault (faults formed from compression) to the north of the Manix fault. Do you think that this change in fault motion on the Calico fault may be related to the termination of the Manix fault?


    • Neotectonic map of the Calico fault and related structural features. (a) Northwestern part. (b) Southeastern part. Strands of the Calico fault shown as black lines, recent earthquake ruptures as white lines, and other active faults as gray lines. Arrows represent strike-slip motion; tics indicate hanging wall of reverse fault. Basement arches are inferred basement-involved folds. Other anticline axes indicate folding of Miocene and younger sedimentary deposits. Synclines are not shown for clarity, except for the axes of the displaced Silver Bell syncline in the Rodman Mountains and the displaced Barstow syncline in the Mud Hills and Calico Mountains. Cross marks tributary of Kane Wash that was filled by Pipkin basalt. Upper part of this tributary was subsequently diverted into Sheep Springs Wash. Sum displacement of markers by the Calico fault diminishes from 9.6 km in the Rodman Mountains [Garfunkel, 1974] to 3 km in the Calico Mountains and the Mud Hills [Dibblee, 1968; McCulloh, 1952; Singleton and Gans, 2005].

  • Here is a map from Reheis et al. (2014) that shows the lake and river systems of this region.


    • Mojave River drainage basin in southern California (modified from Enzel and others, 2003). During historic high-precipitation years, most recently in early 2005 and late 2010, storms in the headwaters of the San Bernardino Mountains generated riverflow into Silver Lake playa and Cronese Lakes. Red line shows approximate map area.

  • This map shows the region of the 2007 Friends of Pleistocene field trip led by Reheis et al. (2007).


    • Map of principal Quaternary faults in the Lake Manix region, based on unpublished mapping of J.L. Redwine, D.M. Miller, and D.J. Lidke (U.S. Geological Survey) and Phelps and others (in press). Dashed faults are poorly exposed or covered. Field trip stops where faults will be discussed are shown. Background image is from Landsat 7.

  • Here is a larger scale map showing more detail about the prehistoric Manix Lake basin extent, the area where Reheis et al. (2014) mapped the geology and stratigraphy of the Manix Basin, and more detailed fault mapping.


    • Index map superimposed on digital orthophoto map showing Pleistocene Lake Manix, surficial geologic map area (red dashed line), and boundaries of 7.5′ USGS quadrangles. Green line is the 543-meters above sea level (masl) highstand level that depicts the minimum extent of Lake Manix during the late
    Pleistocene; western margin is not known due to progradation during highstands and later burial by Mojave River alluvium. Purple line is the 558-m lake limit projected from highest unfaulted shoreline features recognized during mapping (Reheis and Redwine, 2008). CMF, Cave Mountain fault; DLF, Dolores Lake fault; MF, Manix fault; PF, Pisgah fault; TCAF, Tin Can Alley fault.

  • There was a magnitude M 6.5 earthquake further to the east of Barstow in 1947. Charles Richter worked on this earthquake.
  • I present the first motion focal mechanism (Dosser, 1990) for this M 6.5 earthquake in the poster.
  • This M 6.5 earthquake is associated with the Manix fault and is interpreted as a left-lateral strike-slip earthquake.
  • Here is a map from Doser (1990) showing the regional faults and earthquake epicenters.


    • Quaternary faults within the Mojave Block (modified from Jennings et al., 1975) and earthquakes of ML => 5.0 (dots) occurring between 1932 and 1989. CF is the Calico fault, and CRF is the Camp Rock fault. Dots labeled NV, GL, and M denote the locations of the Homestead Valley, Galway Lake, and Manix sequences.

  • Here is a map from Richter (1947).
  • Note the epicenter is shown as a black circle labeled “instrumental epicenter.” Also, how the famous Route 66 is and that US 91 is located where Interstate 15 currently is.


    • I guess if one is Charles Richter, they don’t need to write a figure caption?

Background Literature – Geodesy

  • Gan et al. (2003) present a summary of geodetic data where they show that the Owens Valley, Little Lake, and Helendale faults form the generalized western boundary of the Eastern California shear zone (there are additional right-lateral faults to the west however).


    • Map showing the location of the ECSZ, the GPS arrays, the station velocities (relative to the fixed North America), and the principal faults in southern California (from Jennings [1992]). The thick dashed lines directed N23°W show the boundaries of the assumed parallel-sided ECSZ. The thin dashed lines extended from the segments of the Garlock fault show the trends of the segments.

  • One of the challenges with interpreting geodetic data is comparing earthquake fault slip rates inferred from geodetic methods with rates calculated using geologic data (either from long term offsets of bedrock, or from more recent rates using fault trenches).
  • Chuang and Johnson (2011) present their comparisons of GPS slip rates with geologic rates.
    • Blue = geologic rate
    • Black = geodetic rate
    • Magenta = block model rate from their analyses


    Comparison of geologic fault slip rates (blue, mm/yr) used in model, range of estimates from elastic block models (black) of Becker et al. (2005) and Meade and Hager (2005), and estimates from our block model (magenta) along major faults. Negative is left lateral. Light red lines are surface fault traces, and white thick lines are model blocks. Blue arrows are Southern California Earthquake Center (SCEC) crustal motion map 3 (Shen et al., 2003) velocities with respect to stable North America.
    *See their paper for fault abbreviations.

  • Here is an interesting figure showing their (Chuang and Johnson, 2011) estimate of the relative position in the earthquake cycle for these faults. This is based on published recurrence intervals for these faults (the average time between earthquakes given paleoseismic investigation data).


    • Summary of assumed geologic rates, recurrence interval (T), and time since last earthquake (teq) in Southern California. (For further discussion of sources of T and teq, see footnote 1). Blue numbers are expert opinion slip rates from Working Group on California Earthquake Probabilities (2008) and red numbers are rates from other paleoseismology data.
    Color of rupture segment represents ratio of time since last earthquake and recurrence interval. Hot (red) colors show segments are in early earthquake cycle, and cold (blue) colors show late earthquake cycle.

  • This is the summary of the Chuang and Johnson (2011) slip rate comparison.


    • A: Geologic fault slip rates versus slip rates inferred from geodetic data. Geologic rates are summarized in Table DR1 (see footnote 1). Blue bars are slip rate comparisons from Meade and Hager (2005) and red bars are from this study. B: Normalized velocity across Garlock fault (blue), Mojave segment of San Andreas fault (red), and eastern California shear zone (ECSZ, green) from our cycle model. Black line is normalized velocity derived from elastic model.

  • Here is an earlier analysis comparing geodetic rates with geologic rates (Dixon et al., 2003). First we see a map showing the faults from which the fault comparisons are shown.


    • Sketch map of study area, modified from Dixon et al. (1995). Bar marks approximate location of Global Positioning System transect (Gan et al., 2000). GF— Garlock fault. Labeled faults of Eastern California shear zone: ALF— Airport Lake fault zone; OVF—Owens Valley fault zone; HMF—Hunter Mountain–Panamint Valley fault zone; DVF— Death Valley–Furnace
    Creek fault zone; FLV— Fish Lake Valley fault zone.

  • Peltzer et al. (2001) use synthetic aperture radar interferometry (see my second update report for more on InSAR anslysis) to measure tectonic deformation that accumulated between 1992-2000.
  • The Coso Geothermal Field is the rainbow area in the northernmost part of the map. Indian Wells Valley is the green area to the south of the Coso Field. This is an area of elevated strain. The Garlock fault is the ~east-west black line in the center of the white inset box.


    • Surface velocity map obtained by averaging 25 interferograms of Los Angeles–Mojave region. One color cycle depicts 10 mm/yr of surface displacement along radar line of sight (at lat N348; ERS [Earth Resource Satellite] descending track trends S13.68W, radar looking westward at 238 off vertical incidence angle in middle of imaged swath). Gray areas are zones of low phase coherence that have been masked in processing. Black lines are active faults (Jennings, 1975). White box indicates subset of synthetic aperture radar (SAR) data that was used for profile in Figure 4. Note conspicuous shear strain along San Andreas fault and shear zone parallel to Blackwater–Little Lake fault system. Large deformation signal in northwest corner of frame is ground subsidence related to Coso volcanic and geothermal field (Fig. 1). Surface displacement associated with 1994 and 1995 Ridgecrest earthquakes is visible south of Coso area. Other patterns of surface deformation include ground subsidence due to groundwater withdrawal in Los Angeles and Lancaster areas (Fig. 1) and to seasonal change of water table level around dry lakes.

  • Peltzer et al. (2001) plot observations from their radar data showing relative plate motion associated with dislocation along the Blackwater-Little Lake fault system.


    • Profiles of observed and modeled line-of-sight displacement projected on vertical plane perpendicular to shear zone. Gray dots are individual data points for all radar-image pixels included in box shown in Figure 3. Solid line shows 2 km running mean of observed displacement along profile length. Note that apparent standard deviation of projected data relative to average profile reflects in part displacement gradient parallel to fault strike and not only error in data. Groups of dots that deviate from dense part of profile are due to ground subsidence near lake shores and to surface displacement associated with Ridgecrest earthquakes (Figs. 1, 3). Short-dash line is profile predicted by long-term velocity model used to estimate interferometric baseline (Shen et al., 1996). Long-dash line is profile predicted by velocity model, including additional buried dislocation along Blackwater–Little Lake fault system. Parameters of added fault are given in text. Black dots and error bars (2s) are line-of-sight projections of horizontal velocities observed by GPS at stations of Yucca transect (Gan et al., 2000).

    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.
  • 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

    • Specific References

  • DeMets, C. and Merkouriev, S., 2016. High-resolution reconstructions of Pacific–North America plate motion: 20 Ma to present in GJI, vol. 207, p. 741–773, https://doi.org/10.1093/gji/ggw305
  • Doser, D.I., 1990. A Re-Examination of the 1947 Manix, California, Earthquake Sequence and Comparison to Other Sequences within the Mojave Block, in BSSA, vol. 80, no. 02, p. 267-277
  • Oskin, M., L. Perg, D. Blumentritt, S. Mukhopadhyay, and A. Iriondo (2007), Slip rate of the Calico fault: Implications for geologic versus geodetic rate discrepancy in the Eastern California Shear Zone, J. Geophys. Res., 112, B03402, doi:10.1029/2006JB004451.
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