Scientist warn Hayward fault expected to produce large quake "any day now"

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KRON/BCN – FREMONT (KRON/BCN) — Scientists warn the Bay Area can expect a much larger quake "any day now" from the fault that produced Tuesday's 4.0-magnitude earthquake in Fremont.

The quake struck at 2:41 a.m. on the Hayward Fault at a depth of 5 miles, according to the U.S. Geological Survey. While the shaking rattled nerves, no major damage was reported.

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But residents may want to take the Bay Area's latest quake as a reminder to be prepared for a "big one."

Scientists warn a much larger quake is due on the Hayward Fault, which extends from San Pablo Bay in the north to Fremont in the south and passes through heavily populated areas including Berkeley, Oakland, Hayward and Fremont.

"We keep a close eye on the Hayward Fault because it does sit in the heart of the Bay Area and when we do get a big earthquake on it, it's going to have a big impact on the entire Bay Area," said Tom Brocher, a research

geophysicist with the USGS.

The last big earthquake on the fault, estimated to have a 6.8-magnitude, occurred in 1868, according to the USGS.

It killed about 30 people and caused extensive damage in the Bay Area, particularly in the city of Hayward, from which the fault gets its name. Until the larger 1906 earthquake, it was widely referred to as the "Great San Francisco Earthquake."

"The population is now 100 times bigger in the East Bay, so we have many more people that will be impacted," said Brocher. "The past five major earthquakes [on the fault] have been about 140 years apart, and now we're 147 years from that 1868 earthquake, so we definitely feel that could happen any time," Brocher said.

Brocher urged residents to take steps to prepare for a major earthquake. But he notes that Tuesday morning's quake was not likely to have much of an impact one way or the other on the likelihood of a major event occurring on the same fault.