The presence of spherulites indicates that a lava flow cooled quickly, and their mineralogy holds clues to its precise cooling history. USGS photo by Jessica Ball
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Large spherulites in Hot Creek rhyolite lava in the Long Valley Caldera
The presence of spherulites indicates that a lava flow cooled quickly, and their mineralogy holds clues to its precise cooling history. USGS photo by Jessica Ball
Panoramic view of the Long Valley Caldera from its north side
This panorama of the Long Valley Caldera, looking from north to south, shows its broad central plain, post-caldera rhyolite flows and uplift on the right, and eastern Sierra Nevada in the background. USGS photo by Jessica Ball.
This panorama of the Long Valley Caldera, looking from north to south, shows its broad central plain, post-caldera rhyolite flows and uplift on the right, and eastern Sierra Nevada in the background. USGS photo by Jessica Ball.
CalVO geologists take paleomag samples from a basaltic andesite lava flow on Ash Creek Butte
Andy Calvert and Tony Pivarunas drill into the face of a lava flow on Ash Creek Butte, a Pleistocene shield volcano northeast of Mount Shasta. USGS photo by Dawnika Blatter
Andy Calvert and Tony Pivarunas drill into the face of a lava flow on Ash Creek Butte, a Pleistocene shield volcano northeast of Mount Shasta. USGS photo by Dawnika Blatter
A digital elevation map of Yellowstone Caldera
Rhyolite lavas in the Yellowstone Caldera younger than 631,000 years
Rhyolite lavas in the Yellowstone Caldera younger than 631,000 years
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, California.
Thurston Lake and Mount Konocti, Clear Lake Volcanic Field, California.
Mammoth Mountain
View of the Mammoth Mountain lava dome complex overlooking Horseshoe Lake.
View of the Mammoth Mountain lava dome complex overlooking Horseshoe Lake.
Eddy covariance station at Mammoth Mountain, California
Photograph of permanent eddy covariance station installed since 2014 in area of volcanic CO2 emissions on Mammoth Mountain, California. USGS photo by Jennifer Lewicki, August 2019.
Photograph of permanent eddy covariance station installed since 2014 in area of volcanic CO2 emissions on Mammoth Mountain, California. USGS photo by Jennifer Lewicki, August 2019.
Rear-arc basalt lava outcrop
A 3-4m (10-12 ft) high outcrop of basalt lava, part of a broader lava flow. These flows were erupted about 300,000 years ago following basalt dike intrusions in a rear-arc region of northern California. The eruptions of three of these flows are thought to have taken place within several hundred years of each other.
A 3-4m (10-12 ft) high outcrop of basalt lava, part of a broader lava flow. These flows were erupted about 300,000 years ago following basalt dike intrusions in a rear-arc region of northern California. The eruptions of three of these flows are thought to have taken place within several hundred years of each other.
Lidar image of Rocky Ridge and raised shorelines along Lake Tahoe
High-resolution, bare-earth, airborne light detection and ranging (LiDAR) image, looking obliquely northwest into Rocky Ridge.
High-resolution, bare-earth, airborne light detection and ranging (LiDAR) image, looking obliquely northwest into Rocky Ridge.
Mount Shasta, a steep-sided Cascade Range stratovolcano in Northern Ca
Mount Shasta, a steep-sided Cascade Range stratovolcano in Northern California, looms above Little Glass Mountain, a thick obsidian flow erupted from the Medicine Lake shield volcano about 1,000 years ago. These are just two of the young volcanic areas monitored by the USGS California Volcano Observatory. USGS photo.
Mount Shasta, a steep-sided Cascade Range stratovolcano in Northern California, looms above Little Glass Mountain, a thick obsidian flow erupted from the Medicine Lake shield volcano about 1,000 years ago. These are just two of the young volcanic areas monitored by the USGS California Volcano Observatory. USGS photo.
Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera.
Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera. The resurgent dome, Doe Ridge, Mammoth Mountain, and the Inyo Craters and Domes all reflect volcanic activity since 760,000 years ago, when a giant eruption formed the caldera.
Simplified geologic map (left) and diagrammatic cross section (right) of Long Valley Caldera. The resurgent dome, Doe Ridge, Mammoth Mountain, and the Inyo Craters and Domes all reflect volcanic activity since 760,000 years ago, when a giant eruption formed the caldera.
Argon geochronology lab in Menlo Park, California.
Argon geochronology lab in Menlo Park, California.
Argon geochronology lab in Menlo Park, California.
Microprobe laboratory in Menlo Park, California.
Microprobe laboratory in Menlo Park, California.
Microprobe laboratory in Menlo Park, California.
Long Valley Caldera map
Map showing distribution of Long Valley postcaldera rhyolites. Abbreviations: CD, Casa Diablo geothermal plant; Ski area, Mammoth Mountain Ski Area; LVEW, Long Valley Exploratory Well, 3 km deep, located high on resurgent uplift; s, surficial deposits filling structural lows on resurgent uplift.
Map showing distribution of Long Valley postcaldera rhyolites. Abbreviations: CD, Casa Diablo geothermal plant; Ski area, Mammoth Mountain Ski Area; LVEW, Long Valley Exploratory Well, 3 km deep, located high on resurgent uplift; s, surficial deposits filling structural lows on resurgent uplift.
Medicine Lake, CA simplified hazards map
Medicine Lake, California simplified hazards map showing potential impact area for ground-based hazards during a volcanic event.
Medicine Lake, California simplified hazards map showing potential impact area for ground-based hazards during a volcanic event.
Hydrotherm program output example
Example Hydrotherm output. Hydrotherm is a three-dimensional simulation of multiphase groundwater flow and heat transport in the temperature range of 0 to 1200 degrees Celsius and the pressure range of 1 to 1000 MPa.
Example Hydrotherm output. Hydrotherm is a three-dimensional simulation of multiphase groundwater flow and heat transport in the temperature range of 0 to 1200 degrees Celsius and the pressure range of 1 to 1000 MPa.
Collecting gases from a hot spring pool near Lassen Peak, California
Inverted funnel connected to thermoplastic tubing used to collect gas from a hot spring pool near Lassen Peak, California.
Inverted funnel connected to thermoplastic tubing used to collect gas from a hot spring pool near Lassen Peak, California.
Flow banding of Panum pumice and obsidian
Flow banding of Panum pumice and obsidian of the same composition.
Flow banding of Panum pumice and obsidian of the same composition.
Salton Sea mud pot
A mud pot releases a burst of gas in the Davis-Schrimpf Seep Field near the Salton Sea. The geothermal area here is related to the same faulting and volcanic system which created the Salton Buttes lava domes. USGS photo by Deb Bergfeld, 2016.
A mud pot releases a burst of gas in the Davis-Schrimpf Seep Field near the Salton Sea. The geothermal area here is related to the same faulting and volcanic system which created the Salton Buttes lava domes. USGS photo by Deb Bergfeld, 2016.
Drew Downs in Iceland
Drew Downs in Iceland with a glacier in hte background.
Drew Downs in Iceland with a glacier in hte background.