A preliminary 4.0-magnitude earthquake struck an area near Emeryville this morning, according to the U.S. Geological Survey.
The earthquake was reported at 6:49 a.m. and was located 1 mile north of Piedmont and 3 miles southeast of Berkeley, USGS officials said.
The temblor had a depth of 3.1 miles.
According to the USGS, the epicenter was two miles from Emeryville, three miles from Oakland, three miles from Berkeley and 64 miles from Sacramento.
The quake was felt most strongly in the East Bay. There were no immediate reports of damage or injury.
Residents said the quake lasted only a few seconds and sounded like a tree limb cracking.
The quake was centered near the junction of the Highway 24 and 13 freeways. Six aftershocks followed.
The temblor appears to have occurred along the Hayward fault, which experts have long said could produce a devastating quake. The fault runs below heavily populated areas of the East Bay. The fault has produced some small quakes recently, including a 4.0 in Fremont in July.