Twin Earthquakes Rattle San Francisco Bay Area, Stirring Memories of 1906 Disaster

SAN FRANCISCO, Calif. — Two earthquakes with magnitudes of at least 3.5 struck near San Francisco over the weekend, according to the United States Geological Survey (USGS). The tremors, which occurred on Friday and Sunday, caused mild shaking but no immediate damage, officials said.

The first quake, a 3.7-magnitude event, struck in the Pacific Ocean off the coast of San Francisco on Friday. Two days later, a 3.5-magnitude quake shook the East Bay near Concord. Both earthquakes were initially reported as magnitude 3.7 but were later revised as seismologists reviewed additional data.

Robert Skoumal, a research geophysicist at the USGS, said the location of Friday’s quake recalled the devastating 7.9-magnitude earthquake that nearly destroyed San Francisco in 1906. Preliminary data suggested both recent quakes occurred along the San Andreas Fault, about two miles west of Golden Gate Park.

“Back in 1906, we didn’t have the best seismic instruments out there,” Skoumal said, noting that it was impossible to determine if the recent quakes shared the exact same epicenter as the historic disaster. He added that earthquakes of similar size are common in the area, with dozens of magnitude 3 quakes recorded over the past few decades.

Despite the region’s seismic risks, Skoumal emphasized that Friday’s quake did not signal an imminent larger event. “I wouldn’t say this particular earthquake should make anyone worried,” he said. Aftershocks, which can occur days, weeks, or even years after an initial quake, are typically minor adjustments along the fault line.

Residents across the Bay Area reported feeling the tremors, but no damage or injuries were reported. The USGS continues to monitor the situation, updating shake-severity maps as more data becomes available.