The third small earthquake in four days rattled the San Francisco Bay Area Saturday, but there were no immediate reports of injury or damage.

The temblor that struck Alameda County at 9:21 a.m. had a preliminary magnitude of 3.5 and a depth of about 6.1 miles, according to the U.S. Geological Survey.

The epicenter was about 2 miles from Berkeley, 3 miles from Piedmont and 3 miles from Emeryville, across the bay from San Francisco.

Residents throughout the Bay Area reported feeling the jolt, but Berkeley police said there were no reports of anyone being hurt by the quake.

Saturday morning's earthquake was similar in magnitude and location to temblors that struck Wednesday and Friday.

The three quakes erupted along the Hayward Fault, which geologists believe is due for a large quake in the potentially lethal 6.7 to 7.0 range.