The chance of a magnitude-8 quake striking the state in the next three decades jumped to 7 percent from 4.7 percent, mainly because scientists took into account the possibility that several faults can shake at once, releasing seismic energy that results in greater destruction.
While the risk of a mega-quake is higher than past estimates, it’s more likely — greater than 99 percent chance — that California will be rattled by a magnitude-6.7 jolt similar in size to the 1994 Northridge disaster. The chance of a Northridge-size quake was slightly higher in Northern California than Southern California — 95 percent versus 93 percent, according to a report released Tuesday by the U.S. Geological Survey.
“California is earthquake country, and residents should live every day like it could be the day of a big one,” USGS geophysicist and lead author Ned Field said.
The latest seismic calculations largely mirror previous findings issued by the USGS in 2008. Back then, scientists also determined that California faced an almost certain risk of experiencing a Northridge-size quake. ….