A pre-dawn earthquake gave parts of Sonoma County an early wake-up call today, as a magnitude 3.7 temblor shook the hills near The Geysers at about 4:21 AM. The quick jolt sent in a flurry of shake reports, but so far, there have been no reports of injuries or structural damage.
Local outlets quickly reported the quake, and according to the Fresno Bee, an initial automated reading from the U.S. Geological Survey was later revised to a magnitude of 3.7 after review by seismologists. The epicenter was reported near the Geysers geothermal complex, with officials logging only a handful of felt reports early in the morning.
Where It Struck
Shake maps placed the epicenter roughly two miles southeast of The Geysers, near the Lake and Sonoma county line, with the quake’s depth listed as essentially at the surface. Shallow quakes like this can feel extra punchy close to the source, even when the magnitude is relatively modest. As of today, there were still no confirmed reports of damage or injury, according to SFGATE.
Why This Area Quakes Often
The Geysers geothermal field is one of the country’s most seismically active zones, and it is not just a result of natural fault lines. Steam extraction and the injection of condensed water for power production alter the pressure and stress in the rock below, which can increase the likelihood of small, shallow quakes. The U.S. Geological Survey notes that those industrial processes, combined with existing regional faults, are a key reason the area sees frequent minor tremors.
What To Do If You Feel It…