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Updated on July 19. Visit the USGS earthquake event page for more information.
Aftershock Forecast
The odds of a subsequent large earthquake continue to drop with time since the mainshock. As of July 18, there is a 1 in 300 chance of a magnitude 7 or greater aftershock, a 3% chance of a magnitude 6 or greater aftershock and a 29% chance of a magnitude 5 aftershock in the next week. The chance of a magnitude 3 or higher earthquake is 99% during the next week. This forecast takes into account the behavior of past sequences in similar tectonic environments and the aftershock sequence observed for this event so far. See detailed forecast here.
Scientists from the USGS and other organizations continue field work and analyses to learn more about the series of earthquakes and aftershocks centered in the Southern California desert near Ridgecrest.
This includes conducting aerial and ground reconnaissance of the extensive surface rupture, deploying temporary seismic and geodetic stations to record aftershocks, and coordinating efforts with military, state, local and academic partners.
The data collected and knowledge gained will help scientists identify which faults broke during the earthquake, determine the extent of faulting and surface displacement, and locate areas of ground failure to better understand the earthquake and its aftershocks. Some of this information helps us refine the USGS National Seismic Hazards Model, a series of maps that reflect what we know about where shaking is likely to occur over decades — information that is used to develop building codes and design structures to withstand the expected shaking.
Instrument Deployments
As of July 11, scientists from USGS, UC Riverside, and the Scripps Institution of Oceanography have deployed temporary equipment including at least 14 seismic and 13 GPS stations as well as five USGS nodal arrays. Additional monitoring equipment will continue to be deployed to learn about this large earthquake.
These locally installed instruments provide more precise measurements of small aftershocks, ground shaking, and ground deformation than more remote regional instruments can.
Measuring Surface Ruptures and Fault Offsets
The earthquakes were large enough that the fault rupture reached the earth’s surface. Field teams in the Ridgecrest area and on the Naval Air Weapons Station China Lake are documenting fault offsets through direct measurements using tools ranging from tape measures to mobile laser scanning. Their observations show that the magnitude 7.1 event caused a maximum of 6 to10 feet of right-lateral offset along about 30 miles of rupture. Rarely is the surface rupture for large earthquakes expressed as a single, clear break, and in this case the rupture along part of its length is unusually broadly distributed.
Aftershocks and Foreshocks — What Has Happened
The aftershock sequence remains very active since the magnitude 7.1 mainshock occurred on July 5. As of July 12, more than 8,900 aftershocks have been recorded including:
On July 12 at 6:11 a.m. Pacific Time a moderate magnitude 4.9 aftershock occurred near Ridgecrest. Aftershocks like this are normal, and in the coming days, seismologists expect additional magnitude 4 or larger aftershocks. So far, all of the magnitude 4 and above aftershocks are occurring within the original aftershock zone.
Aftershock Forecast
The odds of a subsequent large earthquake continue to drop. During the week starting July 11, the USGS forecasts a 1 in 200 chance of a magnitude 7 or larger aftershock and a 43% chance of a potentially damaging magnitude 5 or larger aftershock. The chance of aftershocks strong enough to feel near the epicenter — magnitude 3 or greater — is virtually certain at more than 99%. Between 39 to 73 such events are expected in the next week.
See the aftershock forecast for details. This forecast will be updated as conditions change.
Relation to Coso Geothermal Field and Other Major Faults
Aftershocks are occurring over about a 37-mile length, with a cluster of activity about 15 miles northwest of the mainshock – with five aftershocks greater than magnitude 4 on July 9 and 10. Interestingly, stopping southeast of the Coso geothermal field. The Coso field itself is having very little aftershock activity. The scientific field teams are closely monitoring the Coso field and have found no evidence of magmatic activity and no changes in steam production.
Aftershocks at the southern end of the rupture extend to the Garlock fault. Some small earthquakes are occurring on or very close to the Garlock fault. The fault zones that caused the recent earthquakes are complex, and whether they might affect the Garlock, San Andreas, or other regional fault systems is uncertain. The USGS is closely monitoring this situation using instruments installed where these fault systems meet.
ShakeMap -- Measuring Earthquake Effects
The California Integrated Seismic Network, a network of about 400 high-quality ground motion sensors, enabled the USGS to produce a map of regional ground shaking shortly after the magnitude 7.1 event. Maximum shaking was estimated at MMI IX (violent) near the epicenter and shaking was very strong (MMI VII) over a broader, approximately 25-mile wide region, including the city of Ridgecrest (see map below).
A newer version called the Global ShakeMap also incorporates public observations reported into Did You Feel It? to produce a regional map in a little more than 3 hours after the origin time.
Aftershock Forecast
According to the current forecast, during the week beginning on July 8, 2019, there is less than a 1 % chance of one or more aftershocks that are larger than magnitude 7.1, and an 8 % chance of a magnitude 6 or larger aftershock. Smaller earthquakes are likely during the next week, with 55 to 120 magnitude 3 or greater aftershocks. Magnitude 3 and above earthquakes are large enough to feel near the epicenter.
The July 5, 2019 magnitude 7.1 earthquake near eastern California’s Searles Valley resulted from shallow strike-slip faulting in the North America plate crust. The magnitude 7.1 event occurred about 34 hours after and about 7 miles northwest of a magnitude 6.4 foreshock on July 4, 2019 at 10:34 a.m. Pacific Time.
The USGS has received more than 40,000 “Did You Feel It?” reports.
During the last three days, scientists with the USGS and California Geological Survey -- with help from the U.S. Navy -- began to survey and map the surface ruptures and offset features that resulted from the earthquake. Results from these investigations will be made public in the coming weeks.
USGS scientists and crews continue to work around the clock on field work, mapping impacted areas and monitoring additional aftershocks to keep the public informed.
The USGS has a revised the alert for economic losses to yellow, meaning that damage is possible, and the impact should be relatively localized. USGS estimates that economic losses will exceed \$10 million dollars, with a 30 % chance that losses exceed \$100 million dollars. Past events with this alert level have required a local or regional level response.
The alert remains at green for shaking-related fatalities.
Aftershock Forecast
According to the current forecast, during the week beginning on July 6, 2019, there is a 2 % chance of one or more aftershocks that are larger than magnitude 7.1. Smaller earthquakes are likely during the next week, with 220 to 330 magnitude 3 or larger aftershocks. Magnitude 3 and above earthquakes are large enough to feel near the epicenter. The number of aftershocks will drop off over time, but a large aftershock can increase the numbers again, temporarily.
No one can predict the exact time or place of any earthquake, including aftershocks. The USGS earthquake forecasts help to understand the chances of having more earthquakes within a given time period in the affected area. The USGS calculates this earthquake forecast using a statistical analysis based on past earthquakes.
The forecast changes as time passes due to decline in the frequency of aftershocks, larger aftershocks that may trigger further earthquakes, and changes in forecast modeling based on the data collected for this earthquake sequence.
ShakeAlert Update
For the magnitude 7.1 earthquake, the ShakeAlert system issued an alert 8.00 seconds after the origin time. The first alert issued estimated the magnitude at 5.5. Within 14 seconds, the system increased its estimated magnitude to 6.3. The USGS is investigating why ShakeAlert underestimated the final magnitude by 0.8 units.
The ShakeAlert system initially estimated the location at 1.6 miles from the ANSS final location, and this measurement did not change significantly. Four stations initially detected the earthquake, with 226 stations contributing to the final alert 40 seconds after detection.
The ShakeAlertLA app was not activated because, as with the earlier magnitude 6.4 earthquake, ShakeAlert estimated no damage in Los Angeles County, the area covered by the app. ShakeAlertLA is currently configured to send alerts for earthquakes of magnitude 5.0 or greater if potential damage from shaking is expected (MMI IV+) in Los Angeles County.
ShakeAlertLA is the nation’s first test of delivering USGS-generated ShakeAlerts to a large population using a city-developed cell phone app. The USGS generates the alerts, but delivery will come by other public and private means -- such as the internet, radio, television, and cellular service -- including the City of Los Angeles ShakeAlertLA app. The City of Los Angeles has been a significant USGS partner in developing the ShakeAlert System in southern California.
Field Work
Scientists from the USGS and other organizations are on the ground and working to learn more about surface ruptures. The assessment includes canvassing the impacted area for fault displacements, including offsets in roads or curbs, distortion of pipelines, and damage to structures.
This research will help scientists understand the earthquakes, which faults broke during the earthquake, and the extent of faulting and surface displacement.
“We have few big earthquakes and we learn something from each one,” said Keith Knudsen, USGS Earthquake Science Center deputy director. “Events like these are an important opportunity to document what happens and could potentially happen in the future.”
The field mapping and seismological work will continue from weeks to months as scientists analyze the collected data.
A magnitude 7.1 earthquake struck southern California on July 5, 2019 at 8:20 p.m. local time (July 6 at 03:20 UTC). This event was centered near the July 4, 2019 magnitude 6.4 earthquake.
The USGS has issued a red alert for economic losses meaning that extensive damage is probable, and the disaster is likely widespread. Estimated economic losses are at least $1 billion dollars, less than 1 % of GDP of the United States. Past events with this alert level have required a national or international level response.
There is a green alert for shaking-related fatalities with a low likelihood of casualties. The closest large population center is Ridgecrest, population 28,000. Strong to very strong shaking and damage has been reported there.
Shaking from the earthquake was felt by millions of people across the region, including the greater Los Angeles and Las Vegas areas. Visit the USGS event page for more information.
If you felt this earthquake, report your experience on the “USGS Did You Feel It?” website for this event.
The USGS operates a 24/7 National Earthquake Information Center in Colorado that can be reached for more information at 303-273-8500.
Learn more about the USGS Earthquake Hazards Program.
US Navy Captain Paul Dale discusses the collaborative efforts between the USGS and Naval Air Weapons Station, China Lake after the Ridgecrest earthquake sequence.
US Navy Captain Paul Dale discusses the collaborative efforts between the USGS and Naval Air Weapons Station, China Lake after the Ridgecrest earthquake sequence.
Scientists from USGS & California Geological Survey viewing vertical fault offset of ~12 +/- 3 foot high fault scarp near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
Scientists from USGS & California Geological Survey viewing vertical fault offset of ~12 +/- 3 foot high fault scarp near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
Fault rupture crosses dirt road, with California Geologial Survey vehicles for scale. Displacement at this location is primarily normal (vertical). Photograph taken near the northern end of the rupture resulting from the M7.1 Searles Valley earthquake.
Fault rupture crosses dirt road, with California Geologial Survey vehicles for scale. Displacement at this location is primarily normal (vertical). Photograph taken near the northern end of the rupture resulting from the M7.1 Searles Valley earthquake.
Oblique photograph showing surface faulting from the M7.1 Searles Valley earthquake. The dirt track (center) is right-laterally offset approximately 2.5 m (~8 ft).
Oblique photograph showing surface faulting from the M7.1 Searles Valley earthquake. The dirt track (center) is right-laterally offset approximately 2.5 m (~8 ft).
USGS Research Geologists Christopher DuRoss measures surface displacement resulting from the M7.1 Searles Valley earthquake.
USGS Research Geologists Christopher DuRoss measures surface displacement resulting from the M7.1 Searles Valley earthquake.
USGS Research Geologists Christopher DuRoss and Jessica Thompson Jobe examine rupture resulting from the M7.1 Searles Valley earthquake.
USGS Research Geologists Christopher DuRoss and Jessica Thompson Jobe examine rupture resulting from the M7.1 Searles Valley earthquake.
USGS Earthquake Science Center Mobile Laser Scanning truck operated by Ben Brooks and Todd Ericksen scanning the surface rupture near the zone of maximum surface displacement of the M7.1 Searles Valley earthquake.
USGS Earthquake Science Center Mobile Laser Scanning truck operated by Ben Brooks and Todd Ericksen scanning the surface rupture near the zone of maximum surface displacement of the M7.1 Searles Valley earthquake.
California Geological Survey and USGS geologists and geophysicists with National Guard and Navy personnel view road damage from 3 to 5 feet of right-lateral motion near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
California Geological Survey and USGS geologists and geophysicists with National Guard and Navy personnel view road damage from 3 to 5 feet of right-lateral motion near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
Team discussion among CGS and USGS earthquake scientists at the location of the primary surface fault rupture where is has disrupted and offset an access road at the NAWS China Lake. The fault runs NW to SE across the road, which runs from west to east. The east side of the road is uplifted relative to the west side.
Team discussion among CGS and USGS earthquake scientists at the location of the primary surface fault rupture where is has disrupted and offset an access road at the NAWS China Lake. The fault runs NW to SE across the road, which runs from west to east. The east side of the road is uplifted relative to the west side.
Fault scarp at offset access road site. Center line has been offset up and to the right as one looks across the fault towards the east.
Fault scarp at offset access road site. Center line has been offset up and to the right as one looks across the fault towards the east.
USGS Seismologists Alan Yong and Elizabeth Cohcran conduct field work near the main rupture between Trona and Ridgecrest California.
USGS Seismologists Alan Yong and Elizabeth Cohcran conduct field work near the main rupture between Trona and Ridgecrest California.
USGS scientists and partners review objectives and group assignments at fault scarp site. The team will deploy seismic instruments to better observe aftershock activity from close in, and to document surface faulting.
USGS scientists and partners review objectives and group assignments at fault scarp site. The team will deploy seismic instruments to better observe aftershock activity from close in, and to document surface faulting.
CGS and USGS geologists and geophysicists with National Guard and Navy personnel plan next phase of helicopter-supported field investigations on Sat., July 6, 2019 at China Lake NAWS.
CGS and USGS geologists and geophysicists with National Guard and Navy personnel plan next phase of helicopter-supported field investigations on Sat., July 6, 2019 at China Lake NAWS.
Right-lateral slip across fractures on a hillside, with shattered ground along the surface fault rupture near Ridgecrest, CA.
Right-lateral slip across fractures on a hillside, with shattered ground along the surface fault rupture near Ridgecrest, CA.
USGS scientist pointing to the fault scarp that shows the fault moved horizontally, as well as laterally.
USGS scientist pointing to the fault scarp that shows the fault moved horizontally, as well as laterally.
Fault scarp close to the epicenter. In this location the fault has a main strand where much of the slip occurred, as well as distributed fractures.
Fault scarp close to the epicenter. In this location the fault has a main strand where much of the slip occurred, as well as distributed fractures.
California State Route 178 SW of Trona, following the M7.1 earthquake. Road is now closed for repairs.
California State Route 178 SW of Trona, following the M7.1 earthquake. Road is now closed for repairs.
Scientists from USGS & CGS and Navy escort, and a UCLA engineer from the GEER team, inspect ~12 +/- 3 foot high fault scarp with from 3 to 5 feet of right-lateral motion near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
Scientists from USGS & CGS and Navy escort, and a UCLA engineer from the GEER team, inspect ~12 +/- 3 foot high fault scarp with from 3 to 5 feet of right-lateral motion near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
Railroad tracks offset right-laterally by about 3 feet; southeast of Hwy. 178.
Railroad tracks offset right-laterally by about 3 feet; southeast of Hwy. 178.
Janis Hernandez (California Geological Survey) measures 18 centimeters of offset across one strand of the fault rupture zone. This measurement was conducted following the Magnitude 6.4 earthquake that struck Searles Valley on July 4, 2019.
Janis Hernandez (California Geological Survey) measures 18 centimeters of offset across one strand of the fault rupture zone. This measurement was conducted following the Magnitude 6.4 earthquake that struck Searles Valley on July 4, 2019.
Measurement of fault offset being done by USGS scientist Ken Hudnut, using the offset of a painted road stripe. This measurement was conducted following the Magnitude 6.4 earthquake that struck Searles Valley on July 4, 2019.
Measurement of fault offset being done by USGS scientist Ken Hudnut, using the offset of a painted road stripe. This measurement was conducted following the Magnitude 6.4 earthquake that struck Searles Valley on July 4, 2019.
US Navy Captain Paul Dale discusses the collaborative efforts between the USGS and Naval Air Weapons Station, China Lake after the Ridgecrest earthquake sequence.
US Navy Captain Paul Dale discusses the collaborative efforts between the USGS and Naval Air Weapons Station, China Lake after the Ridgecrest earthquake sequence.
Scientists from USGS & California Geological Survey viewing vertical fault offset of ~12 +/- 3 foot high fault scarp near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
Scientists from USGS & California Geological Survey viewing vertical fault offset of ~12 +/- 3 foot high fault scarp near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
Fault rupture crosses dirt road, with California Geologial Survey vehicles for scale. Displacement at this location is primarily normal (vertical). Photograph taken near the northern end of the rupture resulting from the M7.1 Searles Valley earthquake.
Fault rupture crosses dirt road, with California Geologial Survey vehicles for scale. Displacement at this location is primarily normal (vertical). Photograph taken near the northern end of the rupture resulting from the M7.1 Searles Valley earthquake.
Oblique photograph showing surface faulting from the M7.1 Searles Valley earthquake. The dirt track (center) is right-laterally offset approximately 2.5 m (~8 ft).
Oblique photograph showing surface faulting from the M7.1 Searles Valley earthquake. The dirt track (center) is right-laterally offset approximately 2.5 m (~8 ft).
USGS Research Geologists Christopher DuRoss measures surface displacement resulting from the M7.1 Searles Valley earthquake.
USGS Research Geologists Christopher DuRoss measures surface displacement resulting from the M7.1 Searles Valley earthquake.
USGS Research Geologists Christopher DuRoss and Jessica Thompson Jobe examine rupture resulting from the M7.1 Searles Valley earthquake.
USGS Research Geologists Christopher DuRoss and Jessica Thompson Jobe examine rupture resulting from the M7.1 Searles Valley earthquake.
USGS Earthquake Science Center Mobile Laser Scanning truck operated by Ben Brooks and Todd Ericksen scanning the surface rupture near the zone of maximum surface displacement of the M7.1 Searles Valley earthquake.
USGS Earthquake Science Center Mobile Laser Scanning truck operated by Ben Brooks and Todd Ericksen scanning the surface rupture near the zone of maximum surface displacement of the M7.1 Searles Valley earthquake.
California Geological Survey and USGS geologists and geophysicists with National Guard and Navy personnel view road damage from 3 to 5 feet of right-lateral motion near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
California Geological Survey and USGS geologists and geophysicists with National Guard and Navy personnel view road damage from 3 to 5 feet of right-lateral motion near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
Team discussion among CGS and USGS earthquake scientists at the location of the primary surface fault rupture where is has disrupted and offset an access road at the NAWS China Lake. The fault runs NW to SE across the road, which runs from west to east. The east side of the road is uplifted relative to the west side.
Team discussion among CGS and USGS earthquake scientists at the location of the primary surface fault rupture where is has disrupted and offset an access road at the NAWS China Lake. The fault runs NW to SE across the road, which runs from west to east. The east side of the road is uplifted relative to the west side.
Fault scarp at offset access road site. Center line has been offset up and to the right as one looks across the fault towards the east.
Fault scarp at offset access road site. Center line has been offset up and to the right as one looks across the fault towards the east.
USGS Seismologists Alan Yong and Elizabeth Cohcran conduct field work near the main rupture between Trona and Ridgecrest California.
USGS Seismologists Alan Yong and Elizabeth Cohcran conduct field work near the main rupture between Trona and Ridgecrest California.
USGS scientists and partners review objectives and group assignments at fault scarp site. The team will deploy seismic instruments to better observe aftershock activity from close in, and to document surface faulting.
USGS scientists and partners review objectives and group assignments at fault scarp site. The team will deploy seismic instruments to better observe aftershock activity from close in, and to document surface faulting.
CGS and USGS geologists and geophysicists with National Guard and Navy personnel plan next phase of helicopter-supported field investigations on Sat., July 6, 2019 at China Lake NAWS.
CGS and USGS geologists and geophysicists with National Guard and Navy personnel plan next phase of helicopter-supported field investigations on Sat., July 6, 2019 at China Lake NAWS.
Right-lateral slip across fractures on a hillside, with shattered ground along the surface fault rupture near Ridgecrest, CA.
Right-lateral slip across fractures on a hillside, with shattered ground along the surface fault rupture near Ridgecrest, CA.
USGS scientist pointing to the fault scarp that shows the fault moved horizontally, as well as laterally.
USGS scientist pointing to the fault scarp that shows the fault moved horizontally, as well as laterally.
Fault scarp close to the epicenter. In this location the fault has a main strand where much of the slip occurred, as well as distributed fractures.
Fault scarp close to the epicenter. In this location the fault has a main strand where much of the slip occurred, as well as distributed fractures.
California State Route 178 SW of Trona, following the M7.1 earthquake. Road is now closed for repairs.
California State Route 178 SW of Trona, following the M7.1 earthquake. Road is now closed for repairs.
Scientists from USGS & CGS and Navy escort, and a UCLA engineer from the GEER team, inspect ~12 +/- 3 foot high fault scarp with from 3 to 5 feet of right-lateral motion near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
Scientists from USGS & CGS and Navy escort, and a UCLA engineer from the GEER team, inspect ~12 +/- 3 foot high fault scarp with from 3 to 5 feet of right-lateral motion near the expected maximum slip locality along the primary tectonic rupture associated with the M 7.1 event.
Railroad tracks offset right-laterally by about 3 feet; southeast of Hwy. 178.
Railroad tracks offset right-laterally by about 3 feet; southeast of Hwy. 178.
Janis Hernandez (California Geological Survey) measures 18 centimeters of offset across one strand of the fault rupture zone. This measurement was conducted following the Magnitude 6.4 earthquake that struck Searles Valley on July 4, 2019.
Janis Hernandez (California Geological Survey) measures 18 centimeters of offset across one strand of the fault rupture zone. This measurement was conducted following the Magnitude 6.4 earthquake that struck Searles Valley on July 4, 2019.
Measurement of fault offset being done by USGS scientist Ken Hudnut, using the offset of a painted road stripe. This measurement was conducted following the Magnitude 6.4 earthquake that struck Searles Valley on July 4, 2019.
Measurement of fault offset being done by USGS scientist Ken Hudnut, using the offset of a painted road stripe. This measurement was conducted following the Magnitude 6.4 earthquake that struck Searles Valley on July 4, 2019.