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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. 

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)

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

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

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

Science

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.
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

Volcano Monitoring at California Volcano Observatory

CalVO monitors volcanoes in California with GPS sensors, tiltmeters, strainmeters, and satellite imagery.
link

Volcano Monitoring at California Volcano Observatory

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

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.
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

Multimedia

A small outcropping of rough gray boulders sits in the middle of a field of dry, tan-colored grass. A metal clipboard leans on one rock to provide scale, and a low hill with a stand of oak trees is visible in the background.
Burdell Mountain andesite lava flow
Burdell Mountain andesite lava flow
Viewed from a rocky ledge, a brown-and-green grassy valley filled with eroded, rolling hills slopes towards a body of water at the lower right. Behind them, more hills covered in oak trees and a line of distant mountains form the horizon.
Quien Sabe Volcanic Field
Quien Sabe Volcanic Field
A small outcropping of rough gray boulders sits in the middle of a field of dry, tan-colored grass. A metal clipboard leans on one rock to provide scale, and a low hill with a stand of oak trees is visible in the background.
Vitrophyre breccia in the Tolay Volcanic Field
Vitrophyre breccia in the Tolay Volcanic Field
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
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