Another 4.0 Earthquake Hits the Bay Area as Seismic Activity Surges

A magnitude 4.0 earthquake shook the Bay Area early Wednesday morning, according to the U.S. Geological Survey. Originally estimated at 4.3, the quake was quickly revised to 4.0 within an hour.

The quake struck at 6:16 a.m., centered about 5 miles east of Gilroy. More than 1,100 people reported feeling the shaking, with reports coming in from San Francisco, Santa Cruz, San Jose and as far north as Marin County. The shaking was strong enough to trigger the regional ShakeAlert system.

Two aftershocks followed within minutes: a magnitude 2.7 at 6:18 a.m. and a magnitude 3.6 at 6:20 a.m.

The Bay Area has experienced a noticeable uptick in seismic activity recently. Wednesday’s quake comes just two days after a 4.1 earthquake rattled Santa Rosa. Since early November, at least 90 small earthquakes have occurred in the East Bay near San Ramon. Despite the increase, seismologists say the cluster does not indicate that a major earthquake is imminent.

Even so, the week’s string of quakes is a reminder that Northern California’s fault lines remain active.