DUBLIN -- A number of small earthquakes with preliminary magnitudes up to 3.2 rattled the area near Dublin Thursday and residents shouldn't be surprised by more to come, according to the U.S. Geological Survey.
A 2.9 tremor struck about 2 miles west of Dublin around 4:20 p.m., with nearly 20 more following in just over three hours, the USGS reported.
The largest, which measured with a magnitude 3.2, struck just before 6:30 p.m. at a depth of 6.6 miles, said spokeswoman Leslie Gordon.
Although the quakes occurred along the Calaveras fault, Gordon said the earthquakes were caused by an "unknown and unnamed" fault line just west of the Calaveras fault.
She said "swarms" of quakes are typical for that fault and could be expected through Friday.
"We do want to watch carefully because it's so close to the Calaveras fault," said Gordon. "We are watching that fault but this is totally normal."
The quake did cause a short delay of Bay Area Rapid Transit trains because of post-earthquake protocol that causes the trains to stop, but the system was back on schedule by 8:30 p.m., officials said.
