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Clear Lake Volcano | John Seach
California, USA
38.97 N, 122.77 W
summit elevation 1439 m
Volcanic field
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.
Further Reading
Stimac, J.A. and Pearce, T.H., 1992. Textural evidence of mafic-felsic magma interaction in dacite lavas, Clear Lake, California. American Mineralogist, 77(7-8), pp.795-809.
Chapman, R.H., 1975. Geophysical study of the Clear Lake region, California (No. NP-22407). California Division of Mines and Geology, Sacramento, CA.
Anderson, C.A., 1936. Volcanic history of the Clear Lake area, California. Bulletin of the Geological Society of America, 47(5), pp.629-664.
Clear Lake Volcano Eruptions
No recent eruptions.