Previously, only jumps of three miles had been observed. Those faults run close to heavily populated areas in eastern Los Angeles County and the Inland Empire.Īt the time, scientists said the imagery gave proof that earthquakes zipping along a fault can jump over gaps as long as seven miles. Scientists said the border quake directed tectonic stress toward Southern California, putting the region at a higher risk for a future quake.ĭata showed the April 4, 2010, quake and its aftershocks triggered movement on at least six faults, including the Elsinore and San Jacinto faults. It also happened in the 7.2 earthquake that hit along the California-Mexico border on Easter Sunday in 2010.

Much larger quakes also showed how this could occur, including two that hit the Mojave Desert in the 1990s: the 1992 magnitude-7.3 Landers earthquake and the 1999 magnitude-7.2 Hector Mine earthquake. Damage was reported in Whittier, Pico Rivera, Los Angeles and Alhambra. That aftershock killed one person, twisted chimneys and broke windows. Three days later, a magnitude-5.6 aftershock hit on a different fault.

The Whittier Narrows earthquake, magnitude 5.9, struck on the Puente Hills thrust fault system on Oct. Many of those faults are in the Los Angeles area. The report says past models generally assumed earthquakes were confined to separate faults - or that long faults such as the San Andreas ruptured in separate segments.īut recent large California earthquakes showed how they could rupture across multiple faults at the same time. “This is a significant advancement in terms of representing a broader range of earthquakes throughout California’s complex fault system.” “The new likelihoods are due to the inclusion of possible multi-fault ruptures, where earthquakes are no longer confined to separate, individual faults but can occasionally rupture multiple faults simultaneously,” said USGS seismologist Ned Field, the lead author of the report. The old forecast calculated a rate of one 8.0 or greater earthquake every 617 years.

Stated another way, the chance of an 8.0 or greater quake in California can be expected once every 494 years.

San andreas mega quake times magazine