Since Thursday, at least 131 earthquakes have been recorded — as small as magnitude 0.2 and as big as magnitude 4 — in the Geysers geothermal steam field in Sonoma and Lake counties.

Two earthquakes struck different parts of Northern California early Thursday morning, according to the U.S. Geological Survey.

An earthquake swarm in Northern California early Thursday was another round of recurring temblors in a seismically active region home to the world's largest geothermal field.