A minor earthquake rattled the San Francisco Bay Area in Northern California on Saturday morning, without causing any damage, a report said.

The quake, which had a magnitude of 3.5, took place at 9:21 a.m. local time with its epicenter at about 9 kilometers underground, according to the U.S. Geological Survey.

Saturday's temblor was the third one in fours days in the area, where two quakes with similar readings struck on Wednesday and Friday, but a seismologist said the spate of shakers is most likely random and nothing to worry about.

The three widely felt but harmless quakes occurred on the Hayward Fault, an area known for periodic seismic activity. Many believe the geologic fault is due for a quake in the potentially lethal 6.7 to 7.0 range.

However, Barbara Romanowicz, director of the UC Berkeley Seismological Laboratory, said the quick succession of earthquakes is a probably coincidence and there is no reason to worry about, according to a report at the website of San Francisco Chronicle newspaper.

The seismologist said quakes occur across the world at uneven rates that fluctuate with no rhyme or reason, and sometimes a large number of quakes can come in quick succession even though they're unrelated.

There have been 314 earthquakes throughout California and Nevada in the past week alone, none of them greater than magnitude 4.3.

Source: Xinhua