An earthquake measuring 3.1 on the Richter scale struck outside Healdsburg on Saturday afternoon.
The quake struck at 2:25 p.m. about five miles northwest of The Geysers geothermal field in the Mayacamas Mountains of eastern Sonoma County, according to the U.S. Geological Survey. It had a depth of less than half a mile underground, the agency said.
There were no immediate reports of damage.
