What’s behind the more than 130 small earthquakes hitting Northern California?

A series of more than 100 earthquakes has hit Northern California, shaking up the Geysers geothermal steam field in Sonoma and Lake counties.

Since Thursday, at least 131 earthquakes have been recorded — as small as magnitude 0.2 and as big as magnitude 4. The largest earthquake was recorded at 5:48 a.m. Pacific time Thursday, with an epicenter 10 miles east of Cloverdale, 20 miles northwest of Calistoga and 26 miles north of Santa Rosa.

Small earthquakes are common in the Geysers geothermal steam field. The Geysers-Clear Lake area is one of California’s eight volcanic areas, and the Geysers steam field — on the southwest area of the volcanic field — is home to one of the world’s most productive geothermal power facilities, according to the U.S. Geological Survey.

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