Earthquake swarm strikes San Ramon area Friday night

SAN RAMON — A cluster of earthquakes struck the San Ramon area Friday night, continuing a pattern of seismic activity in recent weeks, according to the U.S. Geological Survey.

Things kicked off at 7:41 p.m. with a magnitude 2.5 centered 3.1 miles southeast of the city.

It was followed by a pair of quakes at 7:49 p.m. — a magnitude 2.9 and a magnitude 3.8. They were centered 3.1 miles and 2.4 miles, respectively, southeast of the city.

The biggest of the bunch — a magnitude 4.0 — hit at 7:56 p.m., 3.1 miles southeast of the city.

The earthquake swarm continued with a magnitude 3.1 at 7:57 p.m. and a magnitude 2.9 at 8:10 p.m. — the temblors were centered about 2.4 miles southeast of the city.

There were no immediate reports of injuries or damage, but BART ran trains at reduced speeds until it completed safety inspections, resulting in a 20-minute delay.

Regular train service resumed just before 8:45 p.m., according to the transit agency.

The San Ramon area has seen notable seismic activity in recent weeks, including magnitude 3.1 and 3.0 temblors on Tuesday. Eight days earlier, three quakes rattled the region over the course of about 100 minutes.

More than 30 earthquakes, including a magnitude 3.7, also were recorded between midnight and 10:15 a.m. on Dec. 8, according to CalTech’s California Earthquake Center.

The area also saw 83 temblors over a 10-day period ending on Nov. 17. They ranged from magnitude 0.6 to 3.8.

Staff writer Rick Hurd contributed to this report. Check back for updates.