Earthquake experts warn that The Big One in Southern California could be even worse than anticipated

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last updated 8 January 2015

For years, experts have been saying "The Big One" — a high-magnitude earthquake that is bound to hit Southern California and cause a devastating amount of death and destruction — will likely occur on the San Andreas fault, which meanders its way through the fringes of the Los Angeles suburbs. But recent activity on the Puente Hills fault has scientists worried that The Big One could be even more catastrophic.

The U.S. Geological Survey and Southern California Earthquake Center have estimated that a large-scale quake on the Puente Hills fault — which runs from northern Orange County through downtown Los Angeles to Hollywood — could kill anywhere from 3,000 to 18,000 people and cause up to $250 billion in damages, the Los Angeles Times reports. The intense destruction would be due to the vulnerability of older buildings in downtown L.A. and Hollywood, and the fact that Puente Hills is a horizontal fault, which means shaking is likely to be felt over a larger area.

By contrast, if a magnitude 8 were to strike on the San Andreas, the damage would still be terrible, but not as severe — the number of estimated deaths is 1,800. To further terrify all Southern California residents, experts think that the Puente Hills fault has a giant quake about every 2,500 years, and they aren't sure when the last one was; Puente Hills was an "invisible" fault until 1999, and was discovered only after scientists put sensors underground. Read more about the fault and the damage it could cause at the Los Angeles Times.