A New Scenario Earthquake for Southern California Based on the January 17, 1994, Northridge Earthquake

Prior to the M 6.8 Northridge, California, earthquake, the two principal scenarios for Southern California were based on a recurrence of a great earthquake (M 8.25) on the San Andreas Fault system and a moderate earthquake (M 6.5) on the Newport-Inglewood fault zone. Like the January 17, 1994, Northridge earthquake, the new scenario event--a blind thrust fault beneath Los Angeles--is expected to generate very high levels of ground shaking (acceleration, velocity, displacement, spectral response) in the epicentral region, trigger ground failure over a wide area; cause extensive damage to the built environment; and test all aspects of the earthquake risk management systems in place in Southern California