Wanderlust World Wanderlust World There is no "Santa Monica Fault." The Greater Los Angeles area's major seismic structures are:
San Andreas Fault: The 1,200 km transform boundary between Pacific and North American plates. Runs ~50 km northeast of downtown LA. Capable of M8+ events. Southern section last ruptured 1857 (Fort Tejon, M7.9); northern section 1906 (San Francisco, M7.9).
Newport-Inglewood Fault Zone: Right-lateral strike-slip system trending northwest through Long Beach, Signal Hill, Inglewood, Culver City, and offshore to Newport Beach. Source of 1933 Long Beach earthquake (M6.4, 120 deaths). Runs closer to Santa Monica than San Andreas.
Hollywood Fault: Runs along base of Santa Monica Mountains through Hollywood, West Hollywood, Beverly Hills. Active, capable of M6.5+.
Santa Monica Fault: Actually exists as a distinct feature!—trending east-west along southern flank of Santa Monica Mountains through Brentwood, Westwood, Santa Monica. Capable of M6.5–7.0. The source's claim is incorrect.
Raymond Fault: Northeast LA through Pasadena, South Pasadena, Alhambra.
Sierra Madre Fault: Southern San Gabriel Mountains front.
LA sits atop a complex fault network. The 1994 Northridge earthquake (M6.7) occurred on a previously unknown blind thrust fault. Building codes, early warning (ShakeAlert), and retrofitting mitigate but don't eliminate risk.