New: Quake on Hayward Fault Shakes Berkeley

Sara Gaiser (BCN)
Tuesday July 21, 2015 - 02:14:00 PM

BART delays and more than a dozen aftershocks were reported in the wake of a 4.0-magnitude earthquake centered on the border of Fremont and Union City this morning, but little or no damage occurred.  

The 2:41 a.m. quake occurred on the Hayward Fault at a depth of 5 miles, and was centered at a spot just north of the intersection of Niles Canyon Road and Mission Boulevard, according to the U.S. Geological Survey. 

The epicenter was located 2 miles north-northeast of Fremont, 2 miles east-southeast of Union City and 4 miles northeast of Newark. 

The U.S. Geological Survey shake map shows residents in the areas close to Fremont and Union City would have felt light shaking, while weaker shaking might have been felt in areas as far south as Santa Cruz, up the Peninsula and as far east as Livermore. 

Residents throughout the Bay Area reported feeling the quake, with responses concentrated in the East and South Bay, according to the USGS. 

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 magnitude 2.7 at 2:56 a.m. 

Fremont police on Twitter reported "lots of calls coming in from nervous and scared residents, but no reports of damage" as of 2:58 a.m. Calls to police and fire agencies for further details have not yet been returned.  

The California Highway Patrol also reported no quake damage in the Fremont and Union City areas. 

BART reported major delays in the early morning hours while trains completed track inspections after the quake. The system was recovering by shortly before 5 a.m., with all tracks inspected and all trains running at normal speeds. 

The Hayward Fault extends from San Pablo Bay in the north to Fremont in the south and passes through Berkeley, Oakland, Hayward and Fremont. 

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, according to the USGS. 

The last major quake on the Hayward Fault, estimated to have been a 6.8-magnitude, occurred in 1868, according to the USGS. It killed about 30 people and caused extensive property damage in the East Bay, particularly in the city of Hayward, from which the fault derives its name.