1915 Imperial Valley earthquakes

Earthquakes in California 1915 Imperial Valley earthquakes USA California California 32.79 -115.56 El Centro 100 left Green pog.svg California 32.8 -115.5 Bullseye1.png 40 yes 250 right 11 seconds 1915-06-23 04:56:00 1915-06-23 03:59:00 n/a ushis572 ushis571 1915 6 22 19:59 PST 20:57 PST 6.25 s yStover Coffman 1993 121 6.25 s y 32.8 N 115.5 W region:US-CA_type:event inline, title Strike-slip United States, Mexico $900,000 8 1 recorded until August 1915 6 dead, several injured The 1915 Imperial Valley earthquakes were two destructive shocks centered near El Centro, California on June 22. The earthquakes measured s y 6.25 and occurred nearly one hour apart at 19:59 and 20:57 PST. Both shocks were assigned VIII (Severe) on the Modified Mercalli intensity scale. Heavy damage occurred in the areas of Mexicali and El Centro, amounting to $900,000. At least six people were killed in the earthquakes. In November, the area was struck by another larger shock, measuring w y 7.0 centered in Cerro Prieto, Baja California, Mexico. Tectonic setting 300x300px|1968 Borrego Mountain earthquake is located in Salton Trough300x300pxBrawley Seismic Zone and surrounding area. The red lines are simplified faults. Right-lateral direction of motion of the transform fault is shown (pink arrows). The red rhombs are pull-apart basins; the northern one is the site of the Niland geothermal field, the southern the Cerro Prieto geothermal field. The Salton Trough is an active pull-apart basin forming due to offsets between the numerous strike-slip faults along its edges. It is a component of the much bigger San Andreas Fault System, joining the San Andreas Fault with the Imperial Fault Zone via the Brawley seismic zone. The San Andreas Fault is the main plate boundary that defines the margin between the Pacific and North American plates in California. However, the plate boundary is slightly more complex; rather than a single fault structure that makes up the boundary, the region is straddled and crisscrossed with numerous shorter faults to accommodate the movement of these two plates.Dorsey R.J San Jacinto Fault Zone in Southern California https://pages.uoregon.edu/rdorsey/sanjacinto.html 13 Dec 2020 Quaternary to Recent Basin Development and Neotectonics of the Central San Jacinto Fault Zone, Southern California The Imperial Fault Zone is a 69-km-long right-lateral strike-slip fault located near the cities of Brawley, Imperial, El Centro, Calexico and Mexicali. The fault is seismically active and was responsible for two damaging earthquakes in 1940 and 1979. In 1966, it produced a magnitude 3.6 earthquake that caused a surface rupture, making it the smallest earthquake associated with such a feature. Earthquakes on the Imperial Fault Zone have a recurrence interval of ~30 years, but larger events like the case of the 1940 w 6.9 earthquake occur every 700 years.Imperial fault zone – Southern California Earthquake Data Center https://scedc.caltech.edu/earthquake/imperial.html Southern California Earthquake Data Center 7 March 2022 June events The earthquakes may have ruptured the northern segment of the Imperial Fault Zone. No surface ruptures have been associated with the earthquakes, and very little is known about the seismic activity of the fault prior to 1940.Aron J. Meltzner Thomas K. Rockwell Late Holocene Earthquake History of the Imperial and Brawley Faults, Imperial Valley, California Report 2004 https://earthquake.usgs.gov/cfusion/external_grants/reports/02HQGR0008.pdf San Diego State University Damage Both shocks were equally severe; around the areas of El Centro and Calexico, buildings were heavily damaged, chimneys collapsed, and walls fell over. The first shock lasted 11 seconds and was strong enough to stop clocks and weaken many buildings in the Imperial Valley. Many people evacuated from their homes and other buildings to stay in the streets. When the second shock came, it caused unreinforced masonry structures to partially collapse, injuring some inhabitants. People who reentered structurally weakened buildings after the first shock were injured during the second. In Mexicali, night entertainment was at its peak hour, so people continued to be entertained even after the first shock. The collapse of walls and falling debris killed six people when the second quake struck.Imperial Valley Earthquake – Southern California Earthquake Data Center https://scedc.caltech.edu/earthquake/imperial1915.html Southern California Earthquake Data Center 7 March 2022 The worst damage occurred at El Centro at an estimated $600,000. Serious damage was reported in Calexico, Heber, and Mexicali, but the economic losses were fewer because El Centro was a much bigger community. Nearly every brick building in the area were damaged, due to poor construction methods which could not withstand the earthquakes' intensity. The two mainshocks were felt as far as San Bernardino and Los Angeles in the north, to Parker and Yuma, Arizona in the east, and south; in Ensenada, and likely beyond. Some fissures were observed in an alluvium fan. Water irrigation installations had minor damage. Riverbanks of the Alamo and New rivers slumped into the stream. At a marsh on the New River, cracks formed. Residents in Mexico reported plumes of steam emitted from a group of mud volcanoes. Sounds of explosions were also heard. Many aftershocks were felt; continuing into August 1915. November event The November 21 w 7.0 earthquake occurred in Baja California, Mexico. The earthquake was assigned IX (Violent) on the Modified Mercalli intensity scale.M 7.0 – 3 km SSW of Ejido Doctor Alberto Oviedo Mota (El Indiviso), Mexico https://earthquake.usgs.gov/earthquakes/eventpage/ushis579/executive United States Geological Survey 7 March 2022 It was associated with a rupture on the Cerro Prieto Fault near a volcano of the same name. Widespread ground slumping, landslides, and liquefaction was reported around Cerro Prieto volcano, 20 km south of the epicenter. The rupture initiated on the fault and propagated bilaterally for a total length of 32 km.Diane I. Doser Contrasts between source parameters of M⩾5.5 earthquakes in northern Baja California and southern California Geophysical Journal International 1994 116 3 605–617 10.1111/j.1365-246X.1994.tb03284.x 1994GeoJI.116..605D free The earthquake caused little damage and no casualties. Plumes of steam up to 200 meters in height were reported in Laguna de los Volcanoes, an uninhabitated area. A massive fissure was reported on both sides of the New River for a length of 3 km. Two individuals at Laguna de los Volcanoes recounted that it was difficult to stand during the earthquake. A levee was damaged. See also List of earthquakes in 1915 List of earthquakes in California List of earthquakes in the United States References http://earthquake.usgs.gov/earthquakes/states/events/1915_06_23.php Historic World Earthquakes United States Geological Survey Earthquake Hazards Program July 30, 2010 https://web.archive.org/web/20101108175813/http://earthquake.usgs.gov/earthquakes/states/events/1915_06_23.php November 8, 2010 dead Sources Stover C.W. Coffman J.L. Seismicity of the United States, 1568–1989 (Revised) https://books.google.com/books?id=bY0KAQAAIAAJ U.S. Geological Survey professional paper 1527 1993 United States Government Printing Office Further reading Carl H. Beal The earthquake in the Imperial Valley, California, June 22, 1915 Bulletin of the Seismological Society of America 5 130–149 GeoScience World 3 10.1785/BSSA0050030130 1915-09-01 1915BuSSA...5..130B 130136110 The earthquake at Volcano Lake, Mexico, November 20, 1915 Bulletin of the Seismological Society of America 6 181–184 GeoScience World 2–3 10.1785/BSSA0060020181 1916-06-01 1916BuSSA...6..181. 239439881 Category:June 1915 in the United States Category:1915 earthquakes Category:1915 in California Category:Earthquakes in California Category:Earthquakes in Mexico Category:1915 in Mexico Category:History of Baja California Category:El Centro metropolitan area Category:Imperial Valley Category:Doublet earthquakes Category:Geology of Imperial County, California Category:1915 disasters in North America