California-Nevada Fault Map centered at 39°N,123°W
Geysers. Ca, near a USGS known volcano, has had a 4.5 mag earthquake and a swarm of smaller quakes before and after the 4.5. It is near a lake that local Native Americans call a 'bottomless' lake, and this lake is actually a collapsed caldera. It is called Clear Lake, and is just north of Santa Rosa, California and the San Francisco Bay Area, about two hours south.
I have seen quake swarms in this area a lot, but this is a bit stronger than usual.
This is an area famous for it's hot springs, and a geothermal experimental powerplant that has recently been shut down - due to fears that drilling and pumping water into the geothermal field may cause earthquakes. Obviously, this latest quake swarm is not due to that drilling and pumping. Or is it?
Often this drill induced quake argument is applied to the Cerro Prieto Geothermal field south of Mexicali, Mexico, but often those voices pointing out the possible risks of drilling and pumping are hushed up.
The area around Cerro Prieto is also volcanic, and is a part of a rifting zone - the same spreading zone that the Salton Buttes volcano sits on. Like Geysers, the area around Cerro Prieto has a good many earthquake swarms and last April had a 7.2 mag quake. Geysers has not had a quake of that magnitude, recently, but does have many quake swarms. Geysers' quakes are very localized within a mile or two, while the quakes around Cerro Prieto is very widespread over tens of miles. Unlike Cerro Prieto, Geysers is not thought to be a part of a rift zone.