A top seismology expert this week reminded Southern California that a major earthquake on the southern San Andreas fault is long overdue.
But exactly what kind of quake, of course, is impossible to know.
Speaking at an earthquake conference this week in Long Beach, Thomas Jordan, director of the Southern California Earthquake Center, said the infamous fault was “locked, loaded and ready to roll.”
A magnitude-8 earthquake striking the southern San Andreas fault would cause massive shaking across a wide swath of Southern California from Monterey County to beyond the Mexican border.
Such an earthquake would be even larger than the 1906 earthquake of San Francisco, a magnitude-7.8 earthquake that became the nation’s deadliest, causing an estimated 3,000 deaths from the shaking and resulting fire. Scientists with the Southern California Earthquake Center produced a video simulation showing what the shaking would look like during a magnitude-8 earthquake in Southern California.
Another earthquake scenario, published by San Diego State University and the San Diego Supercomputer Center, show the sweeping scale of shaking, in red and blue colors, from a theoretical magnitude-7.8 earthquake that begins near the Salton Sea and heads toward Los Angeles. The area in green is permanently deformed by the earthquake, mostly located closest to the San Andreas fault. Note how shaking is particularly long lasting in the Los Angeles Basin, where shaking is amplified by the region’s soft soils.
Finally, here is a visualization of the ShakeOut scenario, depicting a magnitude-7.8 earthquake that also begins at the Salton Sea and moves northwest. Such an earthquake would cause shaking that lasts for nearly two minutes, causing strong shaking closest to the fault, like the Coachella Valley, Inland Empire and Antelope Valley. It would also create pockets of strong shaking elsewhere, like the San Gabriel Valley and East Los Angeles, in which soft soils trap the shaking waves.
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