Clear Lake Volcanic Field is located about 90 miles north of San Francisco, California. The town of Clear Lake lies within the volcanic field as does much of the 43,000-acre fresh water lake of its namesake. The Geysers steam field, which sits at the southwest margin of the volcanic region, is host to one of the world’s most productive geothermal fields, producing enough electricity for 850,000 homes. The heat driving the geothermal system emanates from a zone of partially molten rock (magma) deep below Clear Lake volcanic field. The volcanic features are Quaternary and include rhyolitic lava dome complexes, cinder cones, and maars of basaltic composition. The most prominent volcanic feature is 300,000 year-old Mount Konocti, rising about 975 m (3,200 ft) above the southwestern shore of the lake. The most recent eruptions occurred about 11,000 years ago around Mount Konocti. Although Clear Lake volcanic field has not erupted for several millennia, sporadic volcanic-type earthquakes do occur, and the numerous hot springs and volcanic gas seeps at in the area point to its potential to erupt again.

Location: California, Lake County
Latitude: 38.97° N
Longitude: 122.77° W
Elevation: 1,439 (m) 4,721 (f)
Volcano type: volcanic field (red map area)
Composition: basalt to rhyolite
Most recent eruption: about 10,000 years ago
Nearby towns: Clearlake, Kelseyville, Lakeport, Lucerne
Alert Level: Normal