Two earthquakes with magnitudes of greater than 3.0 struck an area in northern Sonoma County today known for frequent quakes.
A 3.1 magnitude earthquake occurred at 5 p.m. one mile north-northeast of The Geysers, at a depth of 3.5 kilometers, according to the U.S. Geological Survey.
A second quake of 3.9 occurred just a minute later at 5:01 p.m., three miles north-northeast of The Geysers and at a recorded depth of zero kilometers.
The region surrounding The Geysers is the largest single geothermal field in the world, according to the U.S. Department of Energy, and continually produces earthquakes between 0.5 and 3.0 on the Richter scale.
The small quakes are related to deep-well injection that the Department of Energy says is necessary for the extended and sustained production of geothermal resources at the site.