Series of 11 earthquakes rattles East Bay

A series of small earthquakes rattled the East Bay on Monday, with 11 quakes recorded in a single day, according to the U.S. Geological Survey.

SAN RAMON, Calif. - A series of small earthquakes rattled the East Bay on Monday, with 11 quakes recorded in a single day, according to the U.S. Geological Survey.

A 2.9-magnitude quake near Piedmont along the Hayward Fault was followed by 10 additional quakes centered near San Ramon. Most measured between magnitude 2.5 and 3.0, though one reached 3.6. All fall within the "small to moderate" range, seismologists said.

Since Nov. 9, more than 80 earthquakes have occurred in the region, a pattern experts say is typical for the Calaveras Fault, which runs from near San Ramon south past Gilroy and connects with the San Andreas Fault near Hollister. Swarms like this have been recorded several times since the 1970s, most recently in 2015.

"Many of these earthquakes have been fairly shallow, so people have felt them, and understandably people are concerned," said Robert de Groot, a scientist with the USGS. "None of these sequences, none of these swarms, have led to larger earthquakes. There’s a very small percentage of these earthquakes that lead to a larger one."

9 small earthquakes shake San Ramon, powerful quake strikes Japan

Nine small to moderate earthquakes struck San Ramon on Monday morning, the largest one clocking in with a magnitude of 3.6, according to the US Geological Survey.

USGS officials encouraged residents to stay prepared by keeping an emergency kit on hand and following "drop, cover and hold on" guidance during shaking. They also recommended installing the ShakeAlert app, which can provide a few seconds of warning before a quake is felt.

While the Bay Area’s recent quakes were minor, a powerful 7.6-magnitude earthquake struck Japan on Monday, triggering a tsunami and injuring several people.

Experts emphasized that small quakes are a natural and expected part of life along Bay Area fault lines.

Even so, some Bay Area residents said the repeated shaking rattled some people at work.

"It was a very scary experience, because I’ve grown up in California, but I don’t think I’ve felt this many earthquakes all at once," said San Ramon resident Gabby Slivka.