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California Volcano Observatory

Find U.S. Volcano

As a part of the U.S. Geological Survey's Volcano Hazards Program, the California Volcano Observatory aims to advance scientific understanding of volcanic processes and lessen the harmful impacts of volcanic activity in the volcanically active areas of California and Nevada. 

Young Volcanoes in California & Nevada

Very High Threat Potential 1
Lassen Volcanic Center
Long Valley Caldera
Mount Shasta
High Threat Potential 1
Clear Lake Volcanic Field
Medicine Lake
Mono-Inyo Chain
Salton Buttes
Moderate Threat Potential 1
Coso Volcanic Field
Mammoth Mountain
Mono Lake Volcanic Field
Soda Lakes (NV)
Ubehebe Craters

1. View the threat rankings of US Volcanoes.

California's Volcanic Hazards Geonarrative

image related to volcanoes. See description

GIS-based interactive website guides you through the eight young volcanic areas within California that pose the highest threat. 

Explore Volcanic Hazard Exposure

Volcano Research Laboratories

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CalVO hosts several laboratories for multidisciplinary research of geologic phenomena. 

Learn About the Labs

CalVO Quick Links

The U.S. Geological Survey California Volcano Observatory (USGS CalVO) was formed in 2012 and is headquartered in Menlo Park and Moffett Field, CA. It replaced the former Long Valley Observatory (LVO), which was established in 1982 to monitor the restless Long Valley Caldera and Mono-Inyo Craters region of Eastern California. CalVO now monitors these and other potentially hazardous volcanoes in California and Nevada to help communities and government authorities understand, prepare for, and respond to, volcanic activity. 

Sixteen young volcanoes designated as Low Threat to Very High Threat are dispersed throughout the State. Partially molten rock (magma) resides beneath at least seven of these—Medicine Lake Volcano, Mount Shasta, Lassen Volcanic Center, Clear Lake Volcanic Field, the Long Valley Volcanic Region, Coso Volcanic Field, and Salton Buttes— producing volcanic earthquakes(seismicity), toxic gas emissions, hot springs, and (or) ground movement (deformation).

News

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Finding the tempo of shield volcanism in California's Cascades

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A brief history of the Lassen Volcano Observatory (1926-1935)

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When it comes to calderas, how big is big?

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Publications

California’s exposure to volcanic hazards

The potential for damaging earthquakes, landslides, floods, tsunamis, and wildfires is widely recognized in California. The same cannot be said for volcanic eruptions, despite the fact that they occur in the state about as frequently as the largest earthquakes on the San Andreas Fault. At least ten eruptions have taken place in the past 1,000 years, and future volcanic eruptions are inevitable.The

Authors
Margaret Mangan, Jessica Ball, Nathan Wood, Jamie L. Jones, Jeff Peters, Nina Abdollahian, Laura Dinitz, Sharon Blankenheim, Johanna Fenton, Cynthia Pridmore
By
Volcano Hazards Program, Volcano Science Center, California Volcano Observatory, Clear Lake Volcanic Field, Coso Volcanic Field, Lassen Volcanic Center, Long Valley Caldera, Mammoth Mountain, Medicine Lake, Mono Lake Volcanic Field, Mono-Inyo Craters, Mount Shasta, Salton Buttes, Soda Lakes, Ubehebe Craters

Database for potential hazards from future volcanic eruptions in California

More than 500 volcanic vents have been identified in the State of California. At least 76 of these vents have erupted, some repeatedly, during the past 10,000 yr. Past volcanic activity has ranged in scale and type from small rhyolitic and basaltic eruptions through large catastrophic rhyolitic eruptions. Sooner or later, volcanoes in California will erupt again, and they could have serious impact

Authors
Melissa N. White, David W. Ramsey, C. Dan Miller
By
Volcano Hazards Program, California Volcano Observatory, Clear Lake Volcanic Field, Coso Volcanic Field, Lassen Volcanic Center, Long Valley Caldera, Mammoth Mountain, Medicine Lake, Mono Lake Volcanic Field, Mono-Inyo Craters, Mount Shasta, Salton Buttes, Soda Lakes, Ubehebe Craters

Science

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Image Collage of Landsat, pollinator, and volcanologist

Volcano Hazards Assessments

Geologists create hazard maps to convey the types of hazards that may occur during future eruptions and to identify the areas of potential impact. Specific hazards to people and property depend on eruption style, the volume of lava erupted, the location of the eruptive vent, the eruption duration, and local hydrologic conditions. As geologic research progresses, these maps are updated and created.
By
California Volcano Observatory
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Volcano Hazards Assessments

Geologists create hazard maps to convey the types of hazards that may occur during future eruptions and to identify the areas of potential impact. Specific hazards to people and property depend on eruption style, the volume of lava erupted, the location of the eruptive vent, the eruption duration, and local hydrologic conditions. As geologic research progresses, these maps are updated and created.
Learn More
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CalVO's Stuart Wilkinson skis out to a remote seismic instrument in...

Volcano Monitoring at California Volcano Observatory

CalVO monitors volcanoes in California with GPS sensors, tiltmeters, strainmeters, and satellite imagery.
By
California Volcano Observatory
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Volcano Monitoring at California Volcano Observatory

CalVO monitors volcanoes in California with GPS sensors, tiltmeters, strainmeters, and satellite imagery.
Learn More
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Image Collage of Landsat, pollinator, and volcanologist

California has active and hazardous volcanoes

Threat rankings issued by the U.S. Geological Survey (USGS) for California identify fifteen volcanic centers of Low-, Moderate-, High-, or Very High Threat.
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California Volcano Observatory
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California has active and hazardous volcanoes

Threat rankings issued by the U.S. Geological Survey (USGS) for California identify fifteen volcanic centers of Low-, Moderate-, High-, or Very High Threat.
Learn More
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Multimedia

A geologist crouches next to a rhyolite outcrop and points to an egg-shaped mass of radiating pink minerals about the size of a cantaloupe. The rest of the rock is pocked with other egg to grapefruit sized pink crystal masses, interspersed with chunky fragments of black glassy lava.
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Large spherulites in Hot Creek rhyolite lava in the Long Valley Caldera
A broad, flat plain covered in dull green sagebrush stretches away from the viewer in this panorama. The photo is being taken from a rocky hill, with snow-capped, sharp peaks on the far side of the plain and low raised hills on the right side of the photo. One geologist is sitting on the rocks at lower right and one geologist is standing and giving a peace sign.
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Panoramic view of the Long Valley Caldera from its north side
Man standing next to rock with hat and high-vis vest. Snow covered mountain in background.
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Phil Dawson at Mount Shasta
In front of an outcrop of matte grey rock splotched with lichens, a young man in an orange safety vest gives a happy thumbs up and an older man sits writing notes in a small notebook and smiles at the camera. The rocks are perched on a moderate slope covered in brushy manzanita and scraggly pine trees.
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CalVO geologists take paleomag samples from a basaltic andesite lava flow on Ash Creek Butte
A digital elevation map of Yellowstone Caldera
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A digital elevation map of Yellowstone Caldera
Mount Konocti as seen from the town of Clear Lake.
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Mount Konocti as seen from the town of Clear Lake.
Thurston Lake and Mount Konocti, Clear Lake Volcanic Field
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Thurston Lake and Mount Konocti, Clear Lake Volcanic Field
A deep blue lake is nestled in pine forest at the foot of a rocky, hilly peak
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Mammoth Mountain
Eddy covariance station at Mammoth Mountain, California
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Eddy covariance station at Mammoth Mountain, California
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Young Volcanoes in California & Nevada

Very High Threat Potential 1
Lassen Volcanic Center
Long Valley Caldera
Mount Shasta
High Threat Potential 1
Clear Lake Volcanic Field
Medicine Lake
Mono-Inyo Chain
Salton Buttes
Moderate Threat Potential 1
Coso Volcanic Field
Mammoth Mountain
Mono Lake Volcanic Field
Soda Lakes (NV)
Ubehebe Craters

1. View the threat rankings of US Volcanoes.

Volcanoes Hazards Program Links