The Earthquake Effect: 30 years after Loma Prieta earthquake, scientists call San Francisco Bay Area ‘Tectonic Time Bomb’ | abc7news.com
He points to what he calls a “smaller” quake, the magnitude 6.0 temblor that hit Napa in 2014. Damage estimates ran up to a billion dollars. But in a magnitude 7.0 or a 7.9 like the one in 1906, Schwartz expects the damage to be spread over a much, much wider area.
“If you have a minute and a half or two minutes of shaking, it’s really unclear what that’s going to do to a lot of structures that are out there,” he added.
The reason California is at such high risk for earthquakes is that we are right on the edge of two huge tectonic plates in the earth’s crust — the Pacific Plate on the west and the North American Plate on the east.
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The San Andreas Fault runs between the two plates, right through California. The Pacific Plate is constantly moving north. The movement is usually so slow we don’t feel it, but sometimes the pressure builds and the ground shoots forward faster, causing an earthquake.