- Status: Clear Lake is monitored by the Long Valley Observatory and is at a background level of activity.
- Volcanic History Overview: The late-Pliocene to early Holocene Clear Lake volcanic field in the northern Coast Ranges, contains lava dome complexes, cinder cones, and maars of basaltic-to-rhyolitic composition. The westernmost site of Quaternary volcanism in California, the Clear Lake field is located far to the west of the Cascade Range in a complex geologic setting within the San Andreas transform fault system. Mount Konocti, a composite dacitic lava dome on the south shore of Clear Lake, is the largest volcanic feature. Volcanism has been largely non-explosive, with only one major airfall tuff and no ash flows. The latest eruptive activity, forming maars and cinder cones along the shores of Clear Lake, continued until about 10,000 years ago. A large silicic magma chamber provides the heat source for the Geysers, the world's largest producing geothermal field.
- Location: Western US, CA
Elevation: 1439 m
Recent Eruption: The most recent eruption was about 10,000 yrs ago based on studies of lake deposits. It was probably a mafic tuff erupted through Clear Lake.
- Hazard Assessments:
- Link to monitoring data:
Volcanic Alert Level: NORMAL Aviation Color Code: GREEN