Earthquake swarm rattles Concord Fault in East Bay

CONCORD, Calif. (KTVU and wires ) – An earthquake swarm with the largest temblor of a 3.6 magnitude rattled residents living near the Concord Fault early Wednesday – the latest in a series of quakes to strike the area since last weekend.

According to the U.S. Geological Survey, the 3.2 quake struck at 7:01 a.m. , a 3.6 at 7:31 a.m. and a 2.6 at 7:35 a.m. on the fault line about one mile south of Concord.

There were no immediate reports of damage or injury and most residents said Wednesday's temblors felt smaller than the weekend shakers.

"I was in the car with my daughter and I felt the car move," said Pleasant Hill resident Solomon Belette. "I didn't know what it was until my wife called and asked if I felt the quake. "It was a small push…The one felt lighter than Sunday."

The experience was similar for Walnut Creek resident Jacob Hopkins.

"It was a little shaking…It wasn't bad at all," he said. "Sunday's quake shook the apartment for about five seconds."

A small earthquake measuring magnitude 2.8 hit the fault line early Monday evening at approximately 6:52 p.m. also one mile south of Concord.

The Concord Fault was also responsible for a magnitude 3.6 quake and several aftershocks Sunday. While it doesn't get the attention of its neighboring faults, experts say it deserves respect.

"Small events show that the stress level is high," USGS seismologist Dr. David Schwartz told KTVU, ''and the Concord fault is one of the major players in the Bay Area."

On a map of seismic activity, the Hayward fault is clustered with a mass of small quakes, dating back more than a decade, showing activity comparable to the Hayward fault to the west.

"Since 2000 the Bay Area has been home to a lot of small earthquakes, most of which you don't feel," explained Schwartz.

Sunday's 3.6 quake, hitting about 3:15 p.m., was felt by many people, in Contra Costa County and beyond.

"It was like a rattling, you know when someone's doing construction, 'Lauren Terrell-Reyes told KTVU, as she headed into the Target store in Pleasant Hill.

In the beverage section of that store, an aisle was taped off due to the quake.

The store manager declined to explain why, but customers said ceiling tiles loosened after the quake and were in danger of falling.

Terrell-Reyes noted, the sales floor shook at her retail job in Walnut Creek as well.

"It was funny because everyone was like, 'what do we do?' I reminded them, it's like in elementary school, let's go back to that!"

Homes, businesses, Bart tracks and industry all sit along the Concord fault.

"We think it can produce a 6.7 or 6.8," observed Dr. Schwartz, "and if it also involves the Green Valley fault to the north into Solano County, then it could be heavy shaking where all the refineries are."