A magnitude 2.6 earthquake was also felt nearby less than 15 minutes following the initial quake.
Keith Knudsen, a United States Geological Service (USGS) geologist and deputy director of the agency’s Earthquake Science Center, referred to Tuesday’s earthquakes as “a garden variety San Andreas event,” the Los Angeles Times reported.
“This is the tenth earthquake larger than magnitude 4 in the last 20 years in this area,” Knudsen explained.
Many of California’s largest earthquakes have occurred along stretches of the San Andreas Fault that are north and south of the creeping section. For example, the 1906 San Francisco earthquake that viciously struck the coast of Northern California occurred about 300 miles north of the San Andreas Fault.
According to David Schwartz, a geologist with the USGS, Tuesday’s quakes occurred along “little fractures” between faults.
“These big faults can be locked, and the stress builds up to the point until the rock can’t hold anymore and it slips. But between these faults there are all these little fractures,” Schwartz told the San Francisco Chronicle.
Even though small quakes may not seem alarming, they can mean trouble, especially if they’re taking place on unmapped faults, Schwartz explained.
“Any earthquake of this magnitude can occur anywhere in the Bay Area at any time,” he said. “I think this was a nice, small example of the larger event that we have in our future. It’s a reminder for people that you can run, but you can’t hide. We are going to have a big earthquake in the Bay Area.”