4 Earthquakes Recorded At The Geysers

THE GEYSERS, CA — Four earthquakes with a magnitude of 2.0 or greater were recorded by the U.S. Geological Survey Thursday morning at The Geysers, a geothermal field at the northeastern edge of Sonoma County.

The first quake happened at 12:13 a.m. Thursday and was a 2.0 that struck less than a half-mile below the earth's surface, according to the USGS. The second, also a 2.0-magnitude, was recorded at 12:20 a.m. and struck 2.4 miles down.

The third, a 2.7-magnitude that struck 0.4 miles down, was recorded at 4:58 a.m. Thursday, according to the USGS.

The fourth earthquake happened at 7:16 a.m. Thursday and was a 2.9-magnitude that struck 1.8 miles below the earth's surface.

A larger quake, a 3.6-magnitude, struck about 220 miles south of The Geysers Thursday morning near Soledad.

The quakes come on the 30th anniversary of the deadly 6.9-magnitude Loma Prieta earthquake. More than 50 people were killed in the Oct. 17, 1989 quake that caused damage in a half-dozen California counties.

The series of shakers also follow two sizable earthquakes this week in the East Bay. The first quake, a 4.5-magnitude, struck Monday night near Pleasant Hill and interrupted operations at two Martinez refineries. That was followed by a 3.2-magnitude temblor Tuesday night beneath Pleasant Hill.

At 5:05 a.m. Saturday, Oct. 12, two earthquakes — a 2.0 and a 2.1 — struck less than a minute apart at The Geysers, according to the USGS.

According to the USGS:

"The Geysers Geothermal Field is located in a tectonically active region of Northern California. The major seismic hazards in the region are from large earthquakes occurring along regional faults that are located miles away from the geothermal field, such as the San Andreas and Healdsburg-Rodgers Creek faults. However, activities associated with the withdrawal of steam for producing electric power cause or induce small quakes to occur in the field. These smaller quakes are frequently felt by those who work at the field and by nearby residents."

— Bay City News Service contributed to this report.