38.97 N, 122.77 W
summit elevation 1439 m
Clear Lake volcanic field is located 135 km north of San Francisco. Volcanic activity is related to extension within the San Adreas fault system.
The volcanic field consists of cinder cones, maars, and lava dome complexes. It is the largest natural freshwater lake in California.
A large magma chamber about 14 km diameter lies 7 km beneath the volcano, which provides the thermal energy for the geysers and geothermal field on SW side of the volcano.
Eruptions at Clear Lake Volcano
Over 100 separate eruptions have been identified in the Clear Lake area. Eruptive products from the first period of activity can be found in the east of the field. The second period of activity built the edifices of Cobb Mountain (1.0 Ma) and Mount Hannah (0.9 Ma). The third period of activity at Clear Lake, volcanic activity occurred at Mount Konocti–Thurston Lake area. This period produced most of the dacite and over half of the rhyolite at the volcanic field.
The most recent activity produced small volume, mostly basaltic and andesitic eruptions, located in the north of the field.
No recent eruptions.