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Monthly Update
Friday, December 01, 2017 1:58 PM US/Pacific
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN
 
California Volcano Observatory's mission
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.

NEWS   (archive)
Young Volcanoes in California & Nevada1

Explore California's volcanic legacy and future with new field trip guides
July 05, 2017

California is well-known for its frequent earthquakes, but less so for its volcanic history – despite the fact that the most recent eruption in the state occurred just 100 years ago. Nearly every kind of volcanic landform is represented in California, from the stratocone of Mount Shasta to the lava domes of the Mono-Inyo Craters to the steam explosion features of Ubehebe Craters. To explore this wealth of geologic phenomena, use some of the USGS's newly published and upcoming volcanic field trip guides!

Several new and updated field guides for the 2017 Scientific Assembly of the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) in Portland, Oregon showcase California's volcanoes. Upcoming publications for Medicine Lake, Mount Shasta, Lassen Peak, Long Valley and Mammoth Mountain will provide easy to follow and informative field trips. The new collection of guidebooks can be found at the USGS Publications Warehouse and summarizes decades of advances in understanding volcanic and tectonic processes of western North America.


New ages confirm that the youngest Eagle Lake volcanic rocks erupted 130-125 thousand years ago
April 03, 2017

New research on the ages of the most recent lava flows at Eagle Lake Volcanic Field, California suggest they are much older than once thought, minimizing the possibility of future eruption. USGS scientists recently released a report about the age of the youngest volcanic deposits at Eagle Lake, CA, in which they concluded that three of the most recent lava flows erupted 130, 127 and 123 thousand years ago. The scientists used stratigraphic, paleomagnetic, and 40Ar/39Ar dating techniques to measure the ages.

Eagle Lake is one of 14 sites in California that was previously identified for potential future volcanism. Originally, geologic mapping was used to interpret the ages of the youngest flows at Eagle Lake. The interpretations from mapping led scientists to believe that eruptions there might have occurred in the Holocene (last 10,000 years). However, the new precise ages show that the flows erupted over a hundred thousand years ago in the Pleistocene. Geologists tend to consider only volcanoes with Holocene-age eruptions to be young enough to potentially erupt again, therefore the likelihood of volcanism from Eagle Lake in the future is extremely low.

Knowing the age of the most recent volcanic eruptions throughout the state helps the California Volcano Observatory (CalVO) plan for, and efficiently deploy, its volcano monitoring resources to locations that have the greatest potential for activity. As a result of the new research at Eagle Lake, CalVO scientists have reconsidered its priority as a location that needs monitoring equipment.


New scientific publications about our California Volcanoes by USGS authors
March 15, 2017

Two new journal articles about California Volcanoes in the eastern part of the state, the Long Valley Caldera and Ubehebe Craters, are headed to press.

Early postcaldera rhyolite and structural resurgence at Long Valley Caldera, California by Wes Hildreth, Judy Fierstein, Andrew Calvert (CalVO, Menlo Park)

After the eruption of 650 cubic kilometers of material known as the Bishop Tuff, forming the Long Valley Caldera, another ~100 cubic kilometers erupted in batches over the next 110,000 years. The paper characterizes the geology of the post-caldera rhyolites.

Eruptive history of the Ubehebe Crater cluster, Death Valley, California by Judy Fierstein, Wes Hildreth (CalVO, Menlo Park)

The Ubehebe Crater cluster in Death Valley National Park was a quick eruption; that is, they all erupted over a short period of time rather than forming over a period of several hundred years. This study has been in our news before, because it documents, in detail, the reasons why Ubehebe Craters are not a long-lived volcanic system, changing previous scientific thinking.