A series of moderate to minor earthquakes struck near the geologically active area in Northern California known as The Geysers south of Clear Lake Thursday morning.

The earthquake swarm started just before 6 a.m., according to the U.S. Geological Survey, with the largest magnitude being a 4.0.

At least four other aftershocks have been recorded, with magnitudes ranging all just under 3.0.

According to USGS, the largest quake should have been felt throughout Lake and Sonoma counties.

There have been no reports of damage at this time. 

The quakes are centered about three miles northwest of The Geysers, a volcanic field prone to minor earthquakes. Thanks to the consistent geothermal activity, a number of steam power plants have been installed in the area.