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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
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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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Sulfur Bank Mine on the western shore of Clear Lake, is one of the ...

Mining and mineralization of the Clear Lake region

The Geysers-Clear Lake area has been one of the most productive in the United States for mercury, and gold was mined in the late 1800s. Many of the deposits are directly associated with outcrops of early Clear Lake volcanic rocks.
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Volcano Science Center, California Volcano Observatory, Clear Lake Volcanic Field, Clear Lake Volcanic Field
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Mining and mineralization of the Clear Lake region

The Geysers-Clear Lake area has been one of the most productive in the United States for mercury, and gold was mined in the late 1800s. Many of the deposits are directly associated with outcrops of early Clear Lake volcanic rocks.
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View from Lookout Mountain of Obsidian Dome and surrounding area....

Long Valley Caldera Field Guide

Ten stops were chosen from published scientific field guides and from California Volcano Observatory field trip notes to represent the geology of the area.
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California Volcano Observatory, Long Valley Caldera
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Long Valley Caldera Field Guide

Ten stops were chosen from published scientific field guides and from California Volcano Observatory field trip notes to represent the geology of the area.
Learn More
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vertical columns of volcanic rock at Devils Postpile National Monument

Vertical columns of volcanic rock at Devils Postpile National Monument

A spectacular display of a columnar-jointed basalt flow.
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California Volcano Observatory, Long Valley Caldera
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Vertical columns of volcanic rock at Devils Postpile National Monument

A spectacular display of a columnar-jointed basalt flow.
Learn More
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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