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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

One schist, two schist, greenschist, blueschist: Metamorphosed volcanic rocks in California

One schist, two schist, greenschist, blueschist: Metamorphosed volcanic rocks in California

Mud pot, mud seep, or mud volcano?

Mud pot, mud seep, or mud volcano?

Examining early 20th-century reports of "activity" at Medicine Lake's Glass Mountain

Examining early 20th-century reports of "activity" at Medicine Lake's Glass Mountain

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 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.
Large spherulites in Hot Creek rhyolite lava in the Long Valley Caldera
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.
Panoramic view of the Long Valley Caldera from its north side
Panoramic view of the Long Valley Caldera from its north side
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.
CalVO geologists take paleomag samples from a basaltic andesite lava flow on Ash Creek Butte
CalVO geologists take paleomag samples from a basaltic andesite lava flow on Ash Creek Butte
A digital elevation map of Yellowstone Caldera
A digital elevation map of Yellowstone Caldera
A digital elevation map of Yellowstone Caldera
Mount Konocti as seen from the town of Clear Lake.
Mount Konocti as seen from the town of Clear Lake.
Mount Konocti as seen from the town of Clear Lake.
Thurston Lake and Mount Konocti, Clear Lake Volcanic Field
Thurston Lake and Mount Konocti, Clear Lake Volcanic Field
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
Mammoth Mountain
Mammoth Mountain
Eddy covariance station at Mammoth Mountain, California
Eddy covariance station at Mammoth Mountain, California
Eddy covariance station at Mammoth Mountain, California
Rear-arc basalt lava outcrop
Rear-arc basalt lava outcrop
Rear-arc basalt lava outcrop