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Sierra Nevada Earthquake Swarm

The USGS California Volcano Observatory (CalVO) is tracking an earthquake swarm in the Sierra Nevada range south of Long Valley Caldera, about 8 miles...

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Earthquake Swarm in Long Valley Caldera Diminishes

Over the past 42 hours, the earthquake swarm in California's Long Valley Caldera, which began last Friday (see September 26 post), has gradually...

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Earthquake Swarm in Long Valley Caldera

We have been closely tracking an earthquake swarm in California's Long Valley Caldera, which started yesterday at around 4AM PDT (September 25, 2014)...

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Mount Shasta debris flow not linked to volcanic activity

On the afternoon of September 20, a large volume of water surged down Mount Shasta's south flank into Mud Creek, entraining debris and inundating the...

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Automated Volcanic-Gas Sniffer Installed at Mammoth Mountain Fumarole

In July 2014, USGS Scientists Peter Kelly (Cascades Volcano Observatory) and Stuart Wilkinson (California Volcano Observatory) installed an automated...

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Investigating Past Eruptions of Mono Craters

CalVO geologist Mae Marcaida examines thin layers of volcanic ash sandwiched between thick beds of sediment deposited by ancestral Mono Lake in...

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Small Earthquake Swarm

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...

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Earthquake swarm under Mammoth Mountain - Update

The earthquake swarm under Mammoth Mountain which started on February 3, 2014 has declined over the past few days. The daily numbers of earthquakes...

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Earthquake swarm under Mammoth Mountain

An earthquake swarm under Mammoth Mountain (Mono County, CA), which started slowly on February 3, 2014 intensified in the early hours of February 5...

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Volcano Hazard Mitigation Included in California Multi-hazard Mitigation Plan

On October 6, 2013 the California Office of Emergency Services (CalOES) published its 2013 State of California Multi-Hazard Mitigation Plan complete...

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Magnitude 3.8 earthquake in Long Valley region is tectonic, and not volcanic, in origin

A magnitude 3.8 earthquake occurred on October 21, 2013 at 10:04 PDT 18 km (11 miles) SE of the town of Mammoth Lakes in eastern California.

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Instrumentation Installed for Continuous Monitoring of Carbon Dioxide Emissions at Horseshoe Lake, Mammoth Mountain

Since 1990, high levels of carbon dioxide (CO2) in the soil have killed trees within about a 75-acre area adjacent to Horseshoe Lake on the south side...

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