Newport–Inglewood Fault

Newport–Inglewood Fault
Name	Newport–Inglewood Fault
Location	Southern California, United States
Length	~47 km
Type	Right-lateral strike-slip with reverse oblique component
Plate	North American Plate
Notable events	1933 Long Beach earthquake

Newport–Inglewood Fault The Newport–Inglewood Fault is a major active strike-slip fault zone in Southern California associated with significant seismic hazard for the Los Angeles metropolitan area, the city of Long Beach, the Port of Los Angeles, and adjacent coastal communities. It traverses or lies near Inglewood, California, Newport Beach, California, Long Beach, California, Huntington Beach, California, and the Los Angeles Basin and has been studied by institutions such as the United States Geological Survey, the California Geological Survey, and the Southern California Earthquake Center. Geologists including researchers from Caltech and University of Southern California have mapped its trace and assessed its rupture potential in collaboration with municipal agencies like the Los Angeles County Metropolitan Transportation Authority and the Port of Los Angeles.

Geology and Structure

The fault is a roughly 47-kilometer-long right-lateral strike-slip fault with an oblique reverse component cutting through late Cenozoic sedimentary rocks of the Los Angeles Basin and the coastal plain near Pacific Coast Highway. Its geometry juxtaposes Miocene and Pliocene strata studied in regional stratigraphic syntheses by the USGS and California Division of Mines and Geology. Surface expression includes linear escarpments, sag ponds, and aligned springs mapped near Cerritos, California, Torrance, California, Redondo Beach, California, and El Segundo, California. Subsurface characterization uses seismic reflection profiles tied to well logs from the Los Angeles County Metropolitan Transportation Authority and petroleum industry data collected by companies that have historically drilled in the Santa Fe Springs Oil Field and Long Beach Oil Field. Structural analyses reference work by the Southern California Earthquake Center and academic groups at University of California, Los Angeles for kinematic models of oblique slip and shallow folding associated with strand linkage between fault segments.

Seismology and Earthquake History

Instrumental and historical records associate the fault with notable events including the magnitude 6.4 1933 Long Beach earthquake that caused extensive damage in Long Beach, Compton, California, and Signal Hill, California and prompted statewide changes such as the Field Act for school construction. Paleoseismic trenching by teams from Caltech and the USGS identified prehistoric surface-rupturing earthquakes and recurrence intervals that inform probabilistic seismic hazard models used by the California Office of Emergency Services. Seismologists from the Southern California Earthquake Data Center and networks like the Parkfield Earthquake Prediction Experiment analogue efforts have cataloged microseismicity along the trace recorded by instruments maintained by USGS, Caltech Seismological Laboratory, and the University of Southern California Southern California Earthquake Center’s earthquake catalogs. Historical newspaper archives from the Los Angeles Times and post-event investigations by the National Research Council have detailed building damage and socioeconomic impacts tied to shaking intensity maps developed by the Federal Emergency Management Agency.

Tectonic Setting and Mechanics

The fault lies within the complex plate boundary region between the Pacific Plate and the North American Plate and interacts with nearby structures including the San Andreas Fault, the Palos Verdes Fault, and the Whittier Fault. Geodetic measurements from GPS networks operated by UNAVCO and strainmeters deployed by Caltech reveal right-lateral shear and localized contraction consistent with transpressional mechanics. Dynamic rupture models by researchers at Lawrence Livermore National Laboratory and academic groups at Massachusetts Institute of Technology and Stanford University simulate how rupture propagation on this fault could link with adjacent faults to produce complex multi-fault earthquakes, a topic also examined in reports by the Southern California Earthquake Center and the USGS National Seismic Hazard Model updates.

Hazard Assessment and Risk Mitigation

Probabilistic seismic hazard assessments produced by the USGS and integrated into building codes by the California Building Standards Commission consider the Newport–Inglewood Fault a capable source for earthquakes up to about magnitude 7. Earthquake engineering research at Stanford University, University of California, Berkeley, and Caltech has informed retrofitting priorities for critical structures including schools regulated under the Field Act, ports overseen by the Port of Los Angeles and Port of Long Beach, lifeline infrastructure managed by Southern California Edison and Los Angeles Department of Water and Power, and transportation corridors like the Interstate 405 (California) and Pacific Coast Highway. Emergency management frameworks by California Office of Emergency Services and municipal plans in Los Angeles and Orange County, California incorporate evacuation, building inspection, and continuity-of-operations strategies based on scenarios developed by the Federal Emergency Management Agency and the National Earthquake Hazards Reduction Program.

Monitoring and Instrumentation

Dense seismic networks operated by the USGS, Caltech Seismological Laboratory, and the Southern California Earthquake Center include broadband seismometers, strong-motion accelerometers, and continuous GPS stations from UNAVCO and the Plate Boundary Observatory. Urban observatories at UCLA and USC host real-time data processing that feeds early warning systems like the ShakeAlert project run by the USGS, Caltech, and University of Washington. Marine seismic reflection surveys by the USGS and academic collaborators have imaged offshore strand segments, while borehole instruments and lidar mapping by the NOAA and the California Geological Survey provide high-resolution topographic and subsurface constraints used in scenario-based hazard modeling.

Urban Impact and Infrastructure Vulnerability

The fault transects densely populated jurisdictions including Los Angeles, Long Beach, Inglewood, California, and Huntington Beach, California and lies near critical facilities such as the Los Angeles International Airport, the Port of Long Beach, rail yards of Metrolink (California), and petrochemical facilities in the Alamitos Bay and Signal Hill, California areas. Vulnerability assessments by the American Society of Civil Engineers, FEMA, and university research centers at UCLA and USC identify risks to lifelines—water supply managed by the Los Angeles Department of Water and Power, electric grids run by Southern California Edison, and freeway overpasses of the Interstate 405 (California) and Interstate 710—with retrofit programs influenced by the California Earthquake Authority and state legislative initiatives. Urban planning documents from Los Angeles County and Orange County, California include mitigation measures informed by scenario-driven loss estimates from the USGS and catastrophe modelers in the private sector.

Category:Seismic faults of California