Skip to main content
U.S. flag

An official website of the United States government

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

image related to volcanoes. See description

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

How hot is hot when it comes to volcanoes?

How hot is hot when it comes to volcanoes?

USGS supercomputers help assess volcanic hazards in support of community resilience

USGS supercomputers help assess volcanic hazards in support of community resilience

Last century's volcanic mudflows at Lassen Peak (May 22, 1915)

Last century's volcanic mudflows at Lassen Peak (May 22, 1915)

View All

Publications

Multidisciplinary constraints on magma compressibility, the pre-eruptive exsolved volatile fraction, and the H2O/CO2 molar ratio for the 2006 Augustine eruption, Alaska

Geodetically modeled reservoir volume changes during volcanic eruptions are commonly much smaller than the observed eruptive volumes. This discrepancy is thought to be partially due to the compressibility of magma, which is largely controlled by the presence of exsolved volatiles. The 2006 eruption of Augustine Volcano, Alaska, produced an eruptive volume that was ∼3 times larger than the geodetic
Authors
Valerie K. Wasser, Taryn M. Lopez, Kyle R. Anderson, Pavel E. Izbekov, Jeffrey T. Freymueller
By
Volcano Hazards Program, Volcano Science Center, California Volcano Observatory

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

Lahar hazard zones for eruption-generated lahars in the Lassen Volcanic Center, California

Lahar deposits are found in drainages that head on or near Lassen Peak in northern California, demonstrating that these valleys are susceptible to future lahars. In general, lahars are uncommon in the Lassen region. Lassen Peak's lack of large perennial snowfields and glaciers limits its potential for lahar development, with the winter snowpack being the largest source of water for lahar generatio
Authors
Joel E. Robinson, Michael A. Clynne
By
Natural Hazards Mission Area, Volcano Hazards Program, Volcano Science Center, California Volcano Observatory
View All

Science

link
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
link

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
link
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
link

Volcano Monitoring at California Volcano Observatory

CalVO monitors volcanoes in California with GPS sensors, tiltmeters, strainmeters, and satellite imagery.
Learn More
link
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.
By
California Volcano Observatory
link

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
View All

Multimedia

Side-view diagram of a thin oceanic layer of the Earth’s crust diving beneath a thick layer of Continental crust
Subduction zone
Subduction zone
A side-view diagram showing a cone of mantle rising underneath a layer of oceanic crust with the ocean on top
Divergent spreading center
Divergent spreading center
A conical, gray, rocky hill rises above a wetland and waterway dotted with bright white wading birds
Salton Buttes
Salton Buttes
An oblique block diagram shows two tectonic plates sliding laterally past each other while sitting atop a section of mantle.
Transform boundary
Transform boundary
A line map of California, Nevada, Oregon, and Idaho is overlaid with tectonic plate boundaries
Mendocino Triple Junction
Mendocino Triple Junction
A scientist in a long silver heat-resistant coat, gas mask, and helicopter helmet inspects a just-quenched sample of lava
Sampling molten lava from the middle East Rift Zone Kīlauea eruption in Nāpau Crater, September 17, 2024
Sampling molten lava from the middle East Rift Zone Kīlauea eruption in Nāpau Crater, September 17, 2024
Shaded relief map showing Lassen Volcanic National Park, with Lassen Peak labeled in the northern portion of the map, Growler & Morgan hot springs to the southwest, and the June 24 2024 swarm to the southeast
Lassen Volcanic Center earthquake swarm of June 24, 2024
Lassen Volcanic Center earthquake swarm of June 24, 2024
Helicorder record showing dozens of tiny earthquake traces occurring over 12 hours, with each line comprising 15 minutes and earthquakes looking like drum cymbals turned on their sides.
LSIB helicorder trace from the Lassen Volcanic Center on June 24, 2024.
LSIB helicorder trace from the Lassen Volcanic Center on June 24, 2024.
Viewed from overhead, the gray and rubbly rhyolite lava domes of the Mono-Inyo Craters are interspersed with smooth patches of volcanic ash and scoria. In the distance, a snow-capped mountain range surrounds a broad lake.
Rhyolite lava domes of the Mono Craters
Rhyolite lava domes of the Mono Craters
View All

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

Was this page helpful?