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.

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.

More than 100 small earthquakes have been recorded near the Geysers geothermal field in Northern California since just after midnight Thursday, according to the U.S. Geological Survey.