Hector Mine — LLMpedia

Hector Mine
Name	Hector Mine earthquake
Date	October 16, 1999
Magnitude	7.1
Depth	20 km
Location	Mojave Desert, San Bernardino County, California
Fault	Lavic Lake Fault Zone / Eastern California Shear Zone

Contents

Hector Mine

The 1999 Hector Mine event was a major intraplate earthquake in the Mojave Desert near Barstow, California and Joshua Tree National Park, striking within the complex fault systems of the Basin and Range Province, the San Andreas Fault system and the Eastern California Shear Zone. It produced widespread seismic waves recorded by the United States Geological Survey, the California Institute of Technology, and international networks such as the Global Seismographic Network, prompting studies by institutions including the Scripps Institution of Oceanography and the Massachusetts Institute of Technology. The earthquake is notable for illuminating fault behavior in the Mojave Desert and influencing hazard assessment by agencies like the Federal Emergency Management Agency and the California Geological Survey.

Background and geology

The quake occurred within the plate-boundary setting influenced by the Pacific Plate and the North American Plate and interacted with strike-slip structures such as the San Andreas Fault, the Garlock Fault, and the Eastern California Shear Zone. The event ruptured portions of the Lavic Lake Fault Zone, linked to faults mapped by the United States Geological Survey and studied in field campaigns by teams from the University of California, Santa Barbara, the University of California, Riverside, and the Southern California Earthquake Center. Regional geology includes exposures of Mojave Desert alluvial fans, Paleozoic rocks studied at Death Valley National Park and Mojave National Preserve, and Quaternary sediments examined by the United States Bureau of Land Management. Paleoseismic investigations by researchers affiliated with the University of Southern California and the California Institute of Technology helped constrain recurrence intervals and slip rates on nearby faults such as the Lavic Lake Fault and subsidiary strands connecting to the San Andreas Fault system.

The October 16, 1999, event registered moment magnitude ~7.1 on catalogs maintained by the United States Geological Survey, the International Seismological Centre, and the Global Centroid Moment Tensor Project. Focal mechanisms determined by analysts at the Seismological Society of America and the California Institute of Technology indicated right-lateral strike-slip motion consistent with regional shear observed along the Eastern California Shear Zone and interactions with the Garlock Fault. Seismic waves were recorded by dense arrays including the ANZA Seismic Network, the Southern California Seismic Network, and research deployments by the USGS Earthquake Hazards Program and the Caltech Seismo Lab. The rupture propagated across desert alluvium documented in mapping efforts by the United States Geological Survey and field crews from the California Geological Survey.

Despite the magnitude and surface rupture crossing remote areas managed by the Bureau of Land Management and near Joshua Tree National Park, impacts on populated centers such as Barstow, Victorville, and Apple Valley, California were comparatively limited due to depth and epicentral location. Structural damage was reported to facilities associated with the Burlington Northern Santa Fe Railway corridors, utility installations managed by Southern California Edison, and infrastructure serving Fort Irwin National Training Center. Casualty reports compiled by the San Bernardino County authorities and summarized by the Federal Emergency Management Agency documented few fatalities and a modest number of injuries, while hospitals in San Bernardino County and Riverside County participated in triage and patient care. Historic sites within Joshua Tree National Park and testing ranges overseen by the U.S. Army reported varying degrees of nonstructural damage.

Postevent science featured coordination among the California Institute of Technology, the United States Geological Survey, the San Diego State University research teams, and international collaborators from institutions such as the National Oceanic and Atmospheric Administration and the World Seismological Network. Field mapping, paleoseismology, and geodetic surveys using the Global Positioning System, interferometric synthetic aperture radar (InSAR) analyzed by researchers at the Jet Propulsion Laboratory, and seismic waveform inversion by groups at the Massachusetts Institute of Technology refined models of slip distribution and stress transfer. Aftershocks populated catalogs maintained by the Southern California Seismic Network and the USGS Earthquake Hazards Program, and triggered seismicity was documented on nearby faults monitored by the California Geological Survey and the Scripps Institution of Oceanography. Workshops and papers presented at the Seismological Society of America meetings and published across journals such as Bulletin of the Seismological Society of America integrated these observations.

Emergency management involved coordination among the Federal Emergency Management Agency, the California Office of Emergency Services, San Bernardino County Fire Department, and local agencies including the Barstow Police Department and Victor Valley Community Hospital. Incident command protocols followed National Incident Management System guidance used by the Department of Homeland Security and were informed by after-action reviews shared with the National Academies of Sciences, Engineering, and Medicine. Recovery efforts included infrastructure inspections by engineers credentialed through the California Structural Engineers Association and utility restorations by Southern California Edison and regional water districts. Federal and state damage assessments guided mitigation funding allocations administered by the Federal Emergency Management Agency and the California Governor's Office.

The earthquake disrupted railroad operations on lines owned by Burlington Northern Santa Fe Railway and impacted high-voltage transmission owned by Southern California Edison and regional distribution managed by municipal water districts and the Los Angeles Department of Water and Power in broader grids. Economic analyses by the Federal Emergency Management Agency and academic economists at the University of California, Berkeley estimated direct and indirect costs including repairs to transportation corridors, testing range facilities for the U.S. Army, and utility systems. The event influenced seismic retrofitting priorities overseen by the California Office of Emergency Services and building code revisions informed by the International Code Council and specialists from the Structural Engineers Association of California and contributed to subsequent hazard planning by metropolitan planning organizations such as the San Bernardino Council of Governments.

Category:Earthquakes in California Category:1999 disasters in the United States