The 'Big One' More Likely to Happen in California, Experts Predict 7 Pct Chance of an Earthquake

Residents of California are facing a 7 percent chance of an earthquake of magnitude 8 or larger over the next three decades, U.S. government scientists said on Tuesday.

The probability of a magnitude 8 or larger quake in California, the experts said, has increased from 4.7 percent estimated in 2008 to 7 percent now.

Meanwhile, they said they now expect moderate-sized earthquakes of magnitudes from 6.5 to 7.5 to be somewhat less frequent than they had previously forecast. Earthquakes of magnitude 6.7 or larger - the size of the 1994 Northridge quake - are projected to strike once every 6.3 years, they said, down from once every 4.8 years.

"What the model really does provide is a significant refinement in our estimates of where and how often earthquakes will occur throughout the state," Field said in an interview on Tuesday, according to the USA Today.

"As we filled in the fault inventory over the years, we've just realized that we're dealing not with separate, isolated faults but a vast, interconnected system of faults," Field said. "The fact that we're now dealing with an interconnected fault system effectively has allowed larger earthquakes to occur in the model, and that has increased the rate of magnitude-8 and above events by about 20%."

An earthquake measuring 3.0 struck along the Hayward Fault shortly after 10 a.m. on Tuesday, according to the U.S. Geological Survey.  The quake at 10:07 a.m. was centered near the Oakland Zoo in the Oakland hills, about 3.5 miles deep.