San Francisco Gets a Wake Up Shake

USGS Scientist: Major Quake On Hayward Fault Expected ‘Any Day Now’

"Any day now" being one of those geologist phrases for "we don't really know when, but it could happen any time"

The 2:41 a.m. earthquake on the border of Fremont and Union City occurred on the Hayward Fault at a depth of 5 miles. The epicenter was at a spot just north of the intersection of Niles Canyon Road and Mission Boulevard.

The quake caused some BART delays early Tuesday while work crews checked the tracks, but appears to have caused no major damage. At least 13 smaller quakes or aftershocks had been reported near the same location as of 6:42 a.m., the largest of which was a 2.7-magnitude at 2:56 a.m.

While damage from the quake was minimal, scientists warn that a much larger one is expected 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.

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 property damage in the Bay Area, particularly in the city of Hayward, from which the fault derives 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 Tom Brocher, a research geophysicist with the USGS.
. . .
While a 2008 report put the probability of a 6.7-magnitude or larger earthquake on the Hayward-Rodgers Creek Fault system over the next 30 years at 31 percent, Brocher said the reality is a major quake is expected on the fault “any day now.”

But most newer buildings are now built to higher standards so I don't expect a proportional level of damage and casualties (which would catastrophic).

But it's not too early to start thinking about it.