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California Volcano Observatory

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The map displays volcanoes, earthquakes, monitoring instruments, and past lava flows.

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To view an earthquake cross-sectional plot, click "Draw Plot" to start drawing on the map. Once the plot area is selected, click on "View Plot" to view chart or "Clear Plot" to start over.

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The map displays volcanoes, earthquakes, monitoring instruments, and past lava flows.

Get Help

Earthquake Plots
To view an earthquake cross-sectional plot, click "Draw Plot" to start drawing on the map. Once the plot area is selected, click on "View Plot" to view chart or "Clear Plot" to start over.

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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 at 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

USGS Releases Five-year Nationwide Strategic Plan for Volcano Hazards

USGS Releases Five-year Nationwide Strategic Plan for Volcano Hazards

Volcanoes and USGS Volcano Science: Just the Facts

Volcanoes and USGS Volcano Science: Just the Facts

California roots of the USGS Volcano Hazards Program

California roots of the USGS Volcano Hazards Program

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Publications

Multidisciplinary constraints on magma compressibility, the pre-eruptive exsolved volatile fraction, and the H2O/CO2 molar ratio for the 2006 Augustine eruption, Alaska 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...
Authors
Valerie Wasser, Taryn M. Lopez, Kyle Anderson, Pavel Izbekov, Jeffrey T. Freymueller
By
Volcano Hazards Program, Volcano Science Center, California Volcano Observatory

California’s exposure to volcanic hazards 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...
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

Eruption probabilities for the Lassen Volcanic Center and regional volcanism, northern California, and probabilities for large explosive eruptions in the Cascade Range Eruption probabilities for the Lassen Volcanic Center and regional volcanism, northern California, and probabilities for large explosive eruptions in the Cascade Range

Chronologies for eruptive activity of the Lassen Volcanic Center and for eruptions from the regional mafic vents in the surrounding area of the Lassen segment of the Cascade Range are here used to estimate probabilities of future eruptions. For the regional mafic volcanism, the ages of many vents are known only within broad ranges, and two models are developed that should bracket the...
Authors
Manuel Nathenson, Michael Clynne, L.J. Muffler
By
Natural Hazards Mission Area, Volcano Hazards Program, Volcano Science Center, California Volcano Observatory
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Multimedia

In this photo of a bare, rocky hill in the middle of a fire-blackened forest, a pole and strapping are laying on the ground next to a charred stump. In the foreground, a dented and warped box contains the melted remains of several large bits of electronics. USGS photo by Ryan Presser, NCSN.
Fire-damaged seismic station in the Lassen Volcanic Center
Fire-damaged seismic station in the Lassen Volcanic Center
A stylized circular logo reads "California Volcano Observatory U.S. Geological Survey" in black on gray font with a central vector image of a brown bear in profile on red ground. Green forests are visible in the mid ground and the two peaks of Mount Shasta and Shastina are shown in the distance.
USGS California Volcano Observatory logo
USGS California Volcano Observatory logo
A silvery scientific instrument in a wooden room. The instrument consists of two open frameworks of slotted gray aluminum bars, in which is a large silver cylinder with another off to it side. Cables and tubes snake out of the instrument to power outlets, motor boxes, and sensor boxes. The instrument is tall and protrudes into an opening in the roof of the room.
Cryogenic magnetometer in the USGS California Volcano Observatory Paleomagnetics Laboratory
Cryogenic magnetometer in the USGS California Volcano Observatory Paleomagnetics Laboratory
Aerial view of Mount Konocti, highlighting Little Borax Lake, the Black Forest landslide scarp and deposits
The lava dome complex of Mount Konocti, Clear Lake Volcanic Field
The lava dome complex of Mount Konocti, Clear Lake Volcanic Field
Map of faults around the Geysers Geothermal Field with the Maacama in green and Collayami in purple
Faults bounding the Geysers Geothermal Complex
Faults bounding the Geysers Geothermal Complex
Map of faults around the Clear Lake volcanic field, highlighting the Bartlett Springs and Maacama faults and the field bounds
Faults bounding the Clear Lake Volcanic Field
Faults bounding the Clear Lake Volcanic Field
An oblique map view of Cobb Mountain and surrounding landscape, featuring Clear Lake, Mount Konocti, and The Geysers
Cobb Mountain and The Geysers geothermal field
Cobb Mountain and The Geysers geothermal field
A geologist wearing a green USGS shirt and ballcap is seen from the back, standing at the top of a hill overlooking a lake and a large mountain. The lake is divided by a long peninsula dotted with homes and trees, and the mountain has two prominent peaks that are covered in dark forest.
Mount Konocti, Clear Lake Volcanic Field, and CalVO geologist Seth Burgess
Mount Konocti, Clear Lake Volcanic Field, and CalVO geologist Seth Burgess
A 3D block diagram showing a cross-section of geologic layers being split by a fault. The block on the right side of the diagram is moving away from the viewer past the block on the left, splitting a surface stream.
Transform fault
Transform fault
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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

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