1987 Superstition Hills earthquakes

Earthquakes in California and Baja California February 2025 1987 Superstition Hills earthquakes California and Mexico 67 3million ci628016 7.5 km 1987-11-24 13:15:56 6.5 w yes November 24, 1987 05:15 PST 2 dead, 94 injured Strike-slip 1987-11-24 01:54:14 1987 Superstition Hills earthquake 33.090 -115.792 region:US inline, title USA California California 34.05 -118.25 Los Angeles 100 Green pog.svg California 36.18 -115.14 Las Vegas 100 top Green pog.svg California 32.72 -117.16 San Diego 100 top Green pog.svg California 33.015 -115.852 Bullseye1.png 40 260 right yes 453653 ci134894 November 23, 1987 17:54 PST 6.0 w yes 2.3 km 453722 The 1987 Superstition Hills earthquake affected the Imperial Valley of California and Baja California on November 24, nearly 12 hours after a w y 6.0 foreshock, called the Elmore Ranch earthquake. The mainshock, measuring w y 6.5, struck at 17:54 PST, along the Superstition Hills segment of the San Jacinto Fault Zone. The earthquake generated a 27 km on surface rupture with additional postseismic slip continuing for a year. The earthquake caused damage amounting to 3million. Damage was considerable in Mexicali, where two people died and 50 were injured. Another 44 people were injured in the Imperial Valley. Buildings in El Centro, Imperial, and Westmorland sustained collapsed chimneys, ruptured pipes, and shattered windows. The rebuilt Imperial County services building, which replaced an originally five-story structure, remained structurally intact. Damage to canal infrastructure cost over 600thousand. Geology The Imperial Valley is a seismically active area in California where the San Andreas Fault and San Jacinto Fault Zone (SJFZ) discontinues. This region represents a transition zone between continental transform faulting and oceanic rifting in the Gulf of California. South of the San Andreas Fault and between the Imperial Fault is the Brawley seismic zone—the northernmost ridge feature in the ridge–transform boundary. Faults in the Brawley Seismic Zone typically trend northeast, perpendicular to the plate boundary faults. Labeled "cross-faults", these are oriented perpendicular to the direction of rifting and were previously interpreted to be normal faults. However, recent seismic activity shows that these faults produce left-lateral strike-slip motion.Hudnut K.W. Seeber L. Rockwell T.K. Goodmacher J. Klinger R. Lindvall S. McElwain R. Surface ruptures on cross-faults in the 24 November 1987 Superstition Hills, California, earthquake sequence 1989 Bulletin of the Seismological Society of America 79 2 282–296 10.1785/BSSA0790020282 July 11, 2025 https://core.ac.uk/download/pdf/216196719.pdf 2024-10-09 2024-10-10 https://web.archive.org/web/20241010070005/https://core.ac.uk/download/pdf/216196719.pdf live The SJFZ is a 244 km-long right-lateral structure that runs parallel to the San Andreas Fault.Singer Eugene Geology of California's Imperial Valley: A Monograph by Eugene Singer http://www.sci.sdsu.edu/salton/San%20AndreasFaultSyst.html 1998 18: The San Andreas Fault System 13 December 2020 https://web.archive.org/web/20110324080539/http://www.sci.sdsu.edu/salton/San%20AndreasFaultSyst.html 24 March 2011 The SJFZ is southern California's most seismically active fault zone. It was responsible for a large surface-rupturing earthquake in 1968. The fault zone is highly segmented, consisting of seven individually named segments.Dorsey Rebecca J. Stratigraphic record of Pleistocene initiation and slip on the Coyote Creek fault, lower Coyote Creek, southern California Contributions to Crustal Evolution of the Southwestern United States https://pages.uoregon.edu/rdorsey/sanjacinto.html 2002 Geological Society of America 10.1130/0-8137-2365-5.251 365 9780813723655 251–269 2022-08-25 2022-10-14 https://web.archive.org/web/20221014225017/https://pages.uoregon.edu/rdorsey/sanjacinto.html live Although part of one fault system, these segments are assigned names such as the Coyote Creek, Superstition Hills, and Superstition Mountain faults. The Superstition Hills Fault (SHF) is a vertically dipping, 38 km-long section.Treiman J.A. Lundberg M. compilers Fault number 125d, San Jacinto fault, Superstition Hills section, in Quaternary fault and fold database of the United States https://earthquake.usgs.gov/cfusion/qfault/show_report_AB_archive.cfm?fault_id=125&section_id=f United States Geological Survey 19 August 2022 1999 25 August 2022 https://web.archive.org/web/20220825105304/https://earthquake.usgs.gov/cfusion/qfault/show_report_AB_archive.cfm?fault_id=125&section_id=f live In 1956, it produced a small surface rupture during a l y 5.6 earthquake. Triggered slip also occurred during earthquakes in 1968 and 1979. The SHF was not known to be capable of producing large earthquakes prior to 1987 although it may have been the source of earthquakes in 1906 and 1915. However, other faults were also candidates for producing these earthquakes.Hudnut K. W. Sieh K. E. Behavior of the Superstition Hills fault during the past 330 years Bulletin of the Seismological Society of America 1989 79 2 304–329 10.1785/BSSA0790020304 July 11, 2025 https://authors.library.caltech.edu/records/kx5md-87h87 2024-10-08 2024-10-08 https://web.archive.org/web/20241008124221/https://authors.library.caltech.edu/records/kx5md-87h87 live Earthquakes Elmore Ranch earthquake The w 6.0 foreshock struck at a depth of 2.3 km, at 17:54 PST. OB 453653 On-line Bulletin http://www.isc.ac.uk/cgi-bin/FormatBibprint.pl?evid=453653 The epicenter was located 22.5 km southwest of Westmorland, in a sparsely populated area.1988 Angela Blanchette Earthquakes Strike Imperial Valley in "Superstition Hills Sequence" http://www.johnmartin.com/earthquakes/eqpapers/00000073.htm California Geology 41 2 https://web.archive.org/web/20040317013833/https://www.johnmartin.com/earthquakes/eqpapers/00000073.htm 17 March 2004 It occurred on a previously unmapped fault, later called the Elmore Ranch Fault Zone (ERFZ).Magistrale Harold Jones Lucile Kanamori Hiroo Hiroo Kanamori April 1989 The Superstition Hills, California, earthquakes of 24 November 1987 https://authors.library.caltech.edu/records/q5jy8-1xh81 Bulletin of the Seismological Society of America 79 2 239–251 0037-1106 10.1785/BSSA0790020239 1989BuSSA..79..239M 9 October 2024 27 July 2024 https://web.archive.org/web/20240727222257/https://authors.library.caltech.edu/records/q5jy8-1xh81 live The aftershocks from this event implied that rupture occurred along a northeast striking fault based on its distribution. The fault ruptured bilaterally for 20–25 km in a northeast towards the Brawley Seismic Zone and southwest, where it joined the SHF. A surface rupture was only observed for half the rupture length and was associated with left-lateral slip with a maximum offset of nearly 20 cm. Between 2.8 cm and 4.8 cm of slip was measured on the Lone Tree, Kane Springs, and Eastern Kane Springs segments of the ERFZ, while the main ERFZ strand had a measured displacement of 13 cm. Superstition Hills earthquake A w 6.5 occurred at 7.5 km depth, OB 453722 On-line Bulletin http://www.isc.ac.uk/cgi-bin/FormatBibprint.pl?evid=453722 12 hours later, with an epicenter at the northwestern termination of the SHF, where it intersects the ERFZ. Its aftershocks illuminated a zone roughly parallel to the SHF, although situated several kilometers southwest of the main rupture trace. The shock caused 27 km of surface rupture running southeastward from the epicenter.https://igppweb.ucsd.edu/~dkilb/NG/SaltonSea/Publications_files/Hudnut-etal_GL016i002p00199.pdf Hudnut K.W. Seeber L. Pacheco J. Cross-fault triggering in the November 1987 Superstition Hills Earthquake Sequence, southern California Geophysical Research Letters 1989 16 2 199–202 10.1029/GL016i002p00199 1989GeoRL..16..199H 2024-10-08 2024-10-10 https://web.archive.org/web/20241010070005/https://igppweb.ucsd.edu/~dkilb/NG/SaltonSea/Publications_files/Hudnut-etal_GL016i002p00199.pdf live Right-lateral offsets were observed along two sections of the SHF and on 4 km of the Wienert Fault.Sharp R. V. Budding K. E. Boatwright J. Ader M. J. Bonilla M. G. Clark M. M. Fumal T. E. Harms K. K. Lienkaemper J. J. Morton D. M. O'Neill B. J. Ostergren C. L. Ponti D. J. Rymer M. J. Saxton J. L. Sims J. D. Surface faulting along the Superstition Hills fault zone and nearby faults associated with the earthquakes of 24 November 1987 Bulletin of the Seismological Society of America 1989 79 2 252–281 10.1785/BSSA0790020252 1989BuSSA..79..252S Over 339 days, the SHF continued to produce aseismic slip, increasing the ground displacements. By August 1988, up to 80.2 cm of offset was measured along the SHF, with much of the slip occurring within the first five days of the mainshock.McGill Sally F. Allen Clarence R. Hudnut Kenneth W. Johnson David C. Miller Wayne F. Sieh Kerry E. Slip on the Superstition Hills fault and on nearby faults associated with the 24 November 1987 Elmore Ranch and Superstition Hills earthquakes, southern California Bulletin of the Seismological Society of America 1989 79 2 362–375 10.1785/BSSA0790020362 1989BuSSA..79..362M https://s3.us-west-2.amazonaws.com/caltechauthors/ea/9b/ce04-9e7c-4896-aa91-c332b04bcb70/data?response-content-type=application%2Foctet-stream&response-content-disposition=attachment%3B%20filename%3D362.full.pdf&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIARCVIVNNAKP37N3MU%2F20231203%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20231203T060500Z&X-Amz-Expires=60&X-Amz-SignedHeaders=host&X-Amz-Signature=7afaa871ddd11b3334082450756b34b35d86d97491384c679ba304c4e687c6ab https://web.archive.org/web/20231203060500/https://s3.us-west-2.amazonaws.com/caltechauthors/ea/9b/ce04-9e7c-4896-aa91-c332b04bcb70/data?response-content-type=application%2Foctet-stream&response-content-disposition=attachment%3B%20filename%3D362.full.pdf&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIARCVIVNNAKP37N3MU%2F20231203%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20231203T060500Z&X-Amz-Expires=60&X-Amz-SignedHeaders=host&X-Amz-Signature=7afaa871ddd11b3334082450756b34b35d86d97491384c679ba304c4e687c6ab 3 December 2023 At the time of observation in 1988, the Wienert Fault's southern portion produced vertical offsets of 25 cm and was actively increasing. The mainshock also triggered slip on the central section of the Coyote Creek Fault, north of the SHF. The 3 km rupture comprised two semi-continuous segments. It had a maximum right-lateral slip of 1.5 cm, and minor vertical offsets were also recorded. Installed creepmeters indicated several millimeters of slip occurred on the San Andreas Fault, but this was insufficient to create a surface rupture. One of these instrument recorded 0.69–0.76 cm of slip. Triggered slip was also measured on the Imperial Fault.Hudnut K. W. Clark M. M. New slip along parts of the 1968 Coyote Creek fault rupture, California Bulletin of the Seismological Society of America 1989 79 2 451–465 10.1785/BSSA0790020451 July 11, 2025 https://www.researchgate.net/publication/279681818 Movements on these faults may have initiated less than three minutes after the two large earthquakes. The Imperial Fault also produced motion about three hours following the mainshock. Ground motion Strong ground motion thumb|A USGS ShakeMap for the November 24 mainshock|alt=A map illustrating the shaking intensities around southern California during the magnitude 6.5 earthquake. The strongest shaking was observed near the epicenter, south of the Salton Sea. Moderate to weak was observed in the surrounding region, including the San Diego, Los Angeles, Tijuana area, and the Mojave desert. Light shaking was also observed in parts of eastern Arizona and southern Nevada. A strong motion network was established by the United States Coast and Geodetic Survey in 1932 to record strong-motion data across the western United States. In the Imperial Valley, an accelerograph was installed at El Centro recorded data for the earthquakes of 1940 and 1987. By 1979, the network expanded to 30 stations in the valley, and nearly 700 strong motion accelerograms were gathered from earthquakes by 1987. The 1987 events produced 65 recordings from 40 stations across the valley. The horizontal peak ground accelerations (pga) during the foreshock exceeded 0.1 g at six stations. The nearest station at Superstition Mountain was 13 km away, recording a pga of 0.13 g. Meanwhile, the highest pga was 0.22 g, measured at Calipatria, 26 km away.Porcella R.L. Etheredge E. Maley R. Switzer J. Strong-motion data from the Superstition Hills earthquakes of 0154 and 1315 [GMT], November 24, 1987 USGS Report 1987 Open-File Report 87-672 2–6 https://pubs.usgs.gov/of/1987/0672/report.pdf United States Geological Survey 1987usgs.rept...44P August 25, 2022 August 25, 2022 https://web.archive.org/web/20220825171206/https://pubs.usgs.gov/of/1987/0672/report.pdf live Twenty-five stations recorded had pga readings exceeding 0.1 g within 60 km of the mainshock's epicenter: all showed at least 0.3 g. The pga at the Superstition Mountain station was the largest and longest ever observed in its 55-year records: 0.9 g and 0.7 g in the horizontal and 0.6 g in the vertical directions. The site also recorded 16 seconds of intense ground motion.Superstition Hills Earthquakes–November 23 and 24, 1987 Imperial County, California https://www.eeri.org/images/archived/wp-content/uploads/USA_CA_SuperstitionHills_Insert_Feb88.pdf Earthquake Engineering Research Institute 8 October 2024 1988 8 October 2024 https://web.archive.org/web/20241008014346/https://www.eeri.org/images/archived/wp-content/uploads/USA_CA_SuperstitionHills_Insert_Feb88.pdf live Damage from the w 6.0 shock in Calipatria, El Centro, Heber, and Westmorland corresponded to VI (Strong) on the Modified Mercalli intensity scale (MMI).California 1987 ci134894 M 6.2 – 17 km WNW of Westmorland, CA The w 6.5 shock had a maximum MMI of VI–VII (Strong–Very strong) at El Centro and Westmorland. Intensity VI was felt at Brawley, Calexico, Calipatria, Heber, Holtville, Imperial, and Seeley. It was widely felt across southern California. The shaking was also felt more than 300 km away in Las Vegas, Nevada, and Tempe, Arizona, and in Mexico's Tijuana and Ensenada.California 1987 ci628016 M 6.6 – 22 km W of Westmorland, CA Impact Although both earthquakes were larger than the Whittier Narrows earthquake of October, damage was moderate because they occurred in a sparsely populated area, estimated at 3million. At least 94 people were injured: 50 in Mexicali and 44 in Imperial County. In Mexicali, two people died after an oncoming vehicle crashed into them while evacuating a factory while some people had broken bones, sprains, cuts and some heart attacks. Thirty-five buildings were damaged, including three hospitals and the city hall. Some 650 people were evacuated from these buildings. An Immigration and Naturalization Service station between the city and Calexico experienced heavy interior damage. Fires also broke out in other buildings.25 November 1987 California gets more reminders of quake potential. Experts say temblors that hit the lower Imperial Valley and Mexicali, Mexico don't mean more are likely to follow soon. 26 August 2022 Scott Armstrong https://www.csmonitor.com/1987/1125/aquake.html The Christian Science Monitor 26 August 2022 https://web.archive.org/web/20220826051346/https://www.csmonitor.com/1987/1125/aquake.html live The w 6.0 shock cut power in parts of Niland but the town was undamaged. In a Westmorland grocery store, merchandise fell and a window cracked. Damage to telephone lines temporarily disrupted communication services in the valley. At the San Onofre Nuclear Plant, there was an "unusual event" declaration. A runway at the Naval Air Facility El Centro was closed for inspections, later revealing small cracks.Feldman Paul Reza H.G. 24 November 1987 Imperial Valley Rocked by 6.2 Quake; Damage Minor Los Angeles Times https://www.latimes.com/archives/la-xpm-1987-11-24-mn-24277-story.html November 21, 2020 2020-11-29 https://web.archive.org/web/20201129091334/https://www.latimes.com/archives/la-xpm-1987-11-24-mn-24277-story.html live Collapsed chimneys, severed pipes, shattered windows, and highways were offset in El Centro, Imperial, and Westmorland. Liquefaction damage rendered a bridge across the New River a complete loss. Near Westmorland, operations at the Desert Test Range Control Center ceased because of a damaged water tank and equipment. Several buildings in Calexico's business district sustained damage, and a brick wall toppled onto some cars. The two-story Imperial County services building, a steel frame structure, only received nonstructural damage. County buildings in El Centro were structurally resilient but had material destruction. The Southern California Irrigation District estimated the damage to its facilities at 600–750thousand. The foreshock caused minor buckling of the canal's concrete reinforcement, while the mainshock collapsed much of the concrete.Carl W. Stover Jerry L. Coffman Seismicity of the United States, 1568-1989 (Revised) Professional Paper 1993 U.S. Geological Survey Professional Paper United States Government Printing Office, Washington 1527 10.3133/pp1527 https://pubs.er.usgs.gov/publication/pp1527 2022-08-25 2022-08-06 https://web.archive.org/web/20220806033204/http://pubs.er.usgs.gov/publication/pp1527 live Concrete channels and pipe siphons had significant damage, and cracking was extensive along the aqueduct. Response The mainshock immediately disrupted power to 65,000 homes and businesses, but it was restored within 20 minutes. Telecommunications, power, and gas services were interrupted throughout Westmorland, El Centro, Calexico and Mexicali. Despite the damage to canal facilities, officials said it did not affect the flow of water. In El Centro, detainees of the Immigration and Naturalization Service were relocated to the courtyard due to damage at the station. Law enforcement officers were on high alert for looters in Calexico. California 86 between Westmorland and El Centro was damaged and closed off. A buckled road near the junction with Interstate 8 also forced California 98 to close. Aircraft from the United States Customs Service and Mexico were flown to inspect the damage. In Orange County, residents stocked up on their earthquake preparedness kits. One store also saw a rise in sales for bottled water, water purification devices, and propane tanks. In La Habra, four households called for a home inspection. The California Department of Transportation dispatched 150 personnel to inspect freeways in the county for damage. The San Diego Fire-Rescue Department reported small cracks in the walls and ceilings at five stations.Reich Kenneth H. G. Reza 25 November 1987 6.3 Quake Injures 94 Along Mexican Border: Imperial Valley Temblor, 2nd in 12 Hours, Damages Buildings in Mexicali, El Centro Los Angeles Times https://www.latimes.com/archives/la-xpm-1987-11-25-mn-16099-story.html 2024-10-08 2024-10-08 https://web.archive.org/web/20241008101945/https://www.latimes.com/archives/la-xpm-1987-11-25-mn-16099-story.html live See also California List of earthquakes in the United States List of earthquakes in California List of earthquakes in Mexico References External links 453653 453722 Superstition Hills earthquakes Superstition Hills earthquakes Superstition Hills earthquakes Category:Earthquakes in California Category:Earthquakes in Mexico Category:History of Imperial County, California Category:Imperial Valley Superstition Hills earthquakes Superstition Hills earthquakes Superstition Hills earthquakes Category:Disasters in California Category:Disasters in Mexico Category:Doublet earthquakes Category:Geology of Imperial County, California Superstition Hills earthquakes Category:Strike-slip earthquakes