Northern California saw a string of minor earthquakes early this week.
On Monday, the USGS reported about 30 small quakes near the Geysers geothermal field south of Clear Lake, following seven quakes in Sonoma County, including a four-point-zero magnitude. Seismologists say the activity is typical for the area, often linked to underground fluids from geothermal operations.
Statewide, earthquake activity this year has been relatively quiet, with only scattered magnitude-four events.
