Bay Area quake: 3.1 near Berkeley, no major damage

A 3.1 magnitude earthquake struck the San Francisco Bay Area on Thursday morning, the U.S. Geological Survey reported, hitting about 9:23 a.m. local time roughly one mile east of Berkeley at a depth of about six miles. The tremor was widely felt across the region but caused no immediate reports of major damage.

The USGS listed the preliminary magnitude at 3.1 and said the quake occurred under Northern California on Oct. 16. More than 2,000 people submitted shaken-but-safe reports to the agency from communities as far south as San Jose and as far north as Santa Rosa. The event took place roughly an hour before scheduled statewide earthquake exercises tied to International ShakeOut Day, an annual preparedness drill that draws millions of participants in California and around the world.

Seismologists cautioned that aftershocks could follow in the coming days. Aftershocks are smaller earthquakes that result from fault adjustments after a main shock and are typically minor, although they can sometimes approach the strength of the initial event, experts said. Given the quake’s modest magnitude and shallow depth, the risk of significant structural damage is low, but officials urged...