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Late night quake jostles East Bay awake

Magnitude 3.4 shaker centered near Oakland/Berkeley border

A photo of Oakland taken from the hills, facing San Francisco Jesse Richmond

The United States Geological Survey (USGS) reports that an earthquake rattled the East Bay early Wednesday morning, the latest reminder of the pressing dangers posed by the Hayward Fault.

USGS says that the magnitude 3.43 quake (initially estimated as a 3.7) hit at about 4:42 a.m. and marks the likely epicenter in Oakland’s Claremont Hills, right next to Bentley School on Hiller Drive.

Within an hour and a half more than 4,000 people had reported feeling the quake, including some testimonies from as far away as Yuba City in Sutter County.

The initial USGS shake map of the quake characterizes the effects as “weak” and predicts that no damage is likely, and thus far there are no reports of injury.

Two mild aftershocks followed, and BART followed its standard procedure and began an immediate track inspection just in case.

In short, it was an entirely routine (if inconveniently timed) East Bay earthquake, of the sort that locals are long since used to.

It is, however, also a reminder that the geological clock is still ticking on the Hayward Fault, which runs from San Jose to Pinole and remains a source of tremendous anxiety for quake watchers.

In a 2008 USGS field guide, geologist Philip W. Stoffer explains:

For its length, the Hayward Fault has probably been studied more than any fault in the world. And for good reason—the Hayward Fault is a known killer. The fault runs through, or near to, some of the most densely urbanized areas in North America.

These areas also support a large portion of California’s economy—the region encompassing the fault is host to a maze of transportation, energy, water, telecommunications, waste disposal, and emergency infrastructure that supports millions of people.

USGS, Phil Stoffer

Stoffer notes that the fault produced a devastating 1868 earthquake that was for decades referred to as the “Great San Francisco Earthquake” before the 1906 SF quake took that title.

“Worst-case scenarios are dire” when it comes to the prospect of future major Hayward quakes, according to Stoffer, who predicts that such a temblor will have national as well as local consequences.

And just such a quake is definitely coming, most likely within the next 30 years according to seismological projections, although of course no one can ever really be sure when an earthquake will occur.

Last year, a new USGS Hayward Fault disaster scenario projected a best case scenario of at least 800 deaths if a 7.0 quake happens along the fault in the near future, as well as “18,000 nonfatal injuries from building and structural damage.”