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California Volcano Observatory (CalVO)

Overlay represents area within CalVO's jurisdiction.
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Monthly Update
Wednesday, July 09, 2014 6:19 PM
Current Volcano Alert Level: UNASSIGNED
Current Aviation Color Code: UNASSIGNED
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

Investigating Past Eruptions of Mono Craters
July 03, 2014
CalVO geologist Mae Marcaida examines thin layers of volcanic ash sandwiched between thick beds of sediment deposited by ancestral Mono Lake in eastern California. Each ash layer is evidence of a past explosive eruption of the Mono Craters, which began erupting about 65,000 years ago just south of present-day Mono Lake. Marcaida and her colleagues use the chemistry of magnetic minerals (titanomagnetites) found in the ash to uniquely "fingerprint" each layer and link it to one of the more than 30 eruptive centers that form the Mono Craters chain. For more information about the Mono Craters ash study see: Geochemical fingerprinting of Wilson Creek tephra layers (Mono Basin, California) using titanomagnetite compositions

Small Earthquake Swarm
June 27, 2014
A swarm of small earthquakes (magnitudes less than 2) occurred at a depth of 6-7 km (about 4 miles) beneath Highway 203 in Mammoth Lakes, California midway between the water treatment plant and the Highway 395-203 junction, June 27, 2014. The swarm began at 4:50 AM and continued with sporadic activity through the morning hours. As of 1:50 PM it appears to have largely died away. We detected no ground deformation associated with this activity, and it poses no immediate hazard.
Volcano Hazard Mitigation Included in California Multi-hazard Mitigation Plan
October 29, 2013
On October 6, 2013 the California Office of Emergency Services (CalOES) published its 2013 State of California Multi-Hazard Mitigation Plan complete with a chapter from the USGS on volcano hazard mitigation. This document is the official statement of the State's hazard identification, vulnerability analysis, and hazard mitigation strategy. Volcanic eruptions occur in California about as frequently as the largest San Andreas Fault Zone earthquakes. Our State Geologist, John Parrish states, "California is the most geologically diverse state in the Nation. We are known for our earthquakes, landslides, and flood hazards. But our nearly forgotten hazard is our volcanoes." With as many as ten eruptions in the last 1,000 years, recognizing the potential for renewed volcanism in California is an essential first step in mitigating hazardous impacts.

You can see the full Mitigation Plan on the CalOES website.