An earthquake with a preliminary magnitude 4.1 struck northern Sonoma County Monday morning, officials said.
According to the U.S. Geological Survey, the earthquake struck less than a mile northwest of the Geysers at 7:08 a.m. An aftershock with a preliminary magnitude of 2.8 struck the same area less than a minute later.
The Geysers geothermal field, known as the world’s largest, is a seismically active region and is home to 18 geothermal power plants…