California could be hit by an 8.2 mega-earthquake, and damage would be catastrophic
The magnitude 8.2 earthquake that ravaged southern Mexico on Thursday was the largest to shake the country in nearly a century.
Like California, Mexico is a seismically active region that has seen smaller quakes that have caused death and destruction. But Thursday’s temblor is a reminder that even larger quakes — while rare — do occur.
Scientists say it’s possible for Southern California to be hit by a magnitude 8.2 earthquake. Such a quake would be far more destructive to the Los Angeles area because the San Andreas fault runs very close to and underneath densely populated areas.
The devastating quakes that hit California over the last century were far smaller than the Thursday temblor, which Mexican authorities set at magnitude 8.2 and the U.S. Geological Survey placed at 8.1. Mexico’s earthquake produced four times more energy than the great 1906 San Francisco earthquake, a magnitude 7.8, which killed 3,000 people and sparked a fire that left much of the city in ruins.
Southern California’s most recent mega-quake was in 1857, also estimated to be magnitude 7.8, when the area was sparsely populated.
Here’s what a hypothetical magnitude 8.2 earthquake would look like in Southern California — a quake that begins near the Mexican border and moves north and west through L.A. County into central California. (Los Angeles Times)
A magnitude 8.2 earthquake would rupture the San Andreas fault from the Salton Sea — close to the Mexican border — all the way to Monterey County. The fault would rupture through counties including Los Angeles, Riverside and San Bernardino.
An 8.2 earthquake would be far worse here because the San Andreas fault runs right through areas such as the Coachella Valley — home to Palm Springs — and the San Bernardino Valley, along with the San Gabriel Mountains north of Los Angeles. The fault is about 30 miles from downtown Los Angeles.
Thursday’s earthquake occurred in the ocean off the Mexican coast and began about 450 miles from Mexico City — and it was relatively deep, starting about 43 miles under the surface.
In Mexico, “you’ve got [many] people a pretty long way aways from it,” seismologist Lucy Jones said Friday. But in Southern California, “we’d have a lot of people right on top of it. It would be shallow, and it runs through our backyard.”
A magnitude 8.2 on the San Andreas fault would cause damage in every city in Southern California, Jones has said, from Palm Springs to San Luis Obispo.
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