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Monthly Update
Wednesday, January 04, 2017 2:46 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

Strong Earthquakes near CA-NV border
December 28, 2016

Three jolting earthquakes occurred in the wee hours this morning near Hawthorne NV, with two M5.7 events and a M5.5 occurring between the hours of 12:18 AM PST and 1:13 AM PST. The earthquakes are related to movement along a NW striking regional fault zone known as the Walker Lane. As of this writing there have been 135 aftershocks, most in the M1-2 range. A similar sequence of earthquakes in April-May 2011 known as the "Hawthorne earthquake swarm" occurred in the same general area.

Although the earthquakes are near Nevada's Aurora-Bodie Volcanic Field (see map), the events are unlikely to be related to volcanic unrest. The lavas of Aurora-Bodie Volcanic Field look "young" but the most recent eruption was 110,000 years ago. The field has a history of eruptions that date as far back as 3.6 million years ago.

More information on the earthquake activity can be found on the University of Nevada, Reno website:

Short-lived Long Valley earthquake swarm does not indicate heightened volcanic unrest.
December 14, 2016

A short-lived earthquake swarm occurred overnight under the Long Valley Caldera in eastern California about 4 km (2.5 mi) ESE of the town of Mammoths Lakes. The swarm does not appear to be related to increased volcanic unrest.

The swarm started with a M2.76 at 11:28 PM PST last night in the South Moat of Long Valley Caldera. This event was followed by a M3.87, the largest event in the swarm, about 15 minutes later. More than forty earthquakes between M1.0 to M3.17 occurred over the ensuing hour. The swarm gradually decayed in numbers of events and earthquake magnitudes over the course of the night to about 10 events of M1.0 or less per hour. Focal depths of earthquakes in the swarm cluster are between about 5-6 km (3-3.8 mi) below Route 203 just west of the junction with Route 395. Swarms of this type are common under the South Moat of Long Valley Caldera. At present, we see no indication of increased volcanic threat to the region.

View current monitoring data on the Long Valley Caldera Monitoring webpage.

CalVO Scientists Present Work at International 2016 AGU Fall Meeting
December 12, 2016

Fifteen CalVO scientists will present work this week at the 2016 American Geophysical Union Fall Meeting, held in San Francisco, California. The meeting is the largest one of its kind in the world: over 20,000 international scientists gather to discuss a wide range of topics and present their work to the Earth and space science community. Our scientists will present research that contributes to understanding volcanic hazards.

This year, CalVO scientist Tom Sisson has been selected as one of 60 new Fellows of the American Geophysical Union, an honor reserved for a small number of AGU members. Fellows are honored for scientific eminence in the Earth and space sciences, which Tom has achieved through his notable discoveries and innovative contributions to scientists' thinking about how magma systems work.

Tom's work applies the results of meticulous petrologic experiments to solve real-world issues surrounding volcano hazards; one example is his great volume of work on Mount Rainier. His work is important to the USGS Volcano Science Center for improving our understanding of volcano hazards, which benefits other volcano researchers and observatories worldwide.

Volcanic hazards in the long term: 3rd Volcano Observatory Best Practices (VOBP) workshop
November 29, 2016

Volcanologists from volcano observatories around the world met at the international Volcano Observatory Best Practices Workshop in Vancouver, Washington from November 15-18th to collaborate on how to best communicate volcanic hazard and risk via long-term assessments. Volcanic hazards are a threat to millions of people who live near the world's 1,550 active volcanoes. Together as a global community of volcanologists we shared ideas, success stories, and useful strategies that are critical to protecting peoples' lives and communities' livelihoods.

An overarching discovery during the meeting was that many best practices are tailored to specific countries and volcanoes, since observatories have variable resources and community involvement. As a result, a variety of hazard assessment approaches were featured, including numerical models and complex databases, user-tailored hazard maps, and new communications strategies and tools—including how to represent long-term volcanic hazards on maps.

CalVO scientists contributed their own thoughts on developing the "next generation" of hazard assessments for US volcanoes, a process that has already begun with updating and revised hazard assessments and maps. The Lassen Volcanic Center assessment (2012) and its accompanying map are the newest of these products to be released for California volcanoes.

Earthquake swarm near Salton Buttes is not volcanic
September 26, 2016

An earthquake swarm started on 26 Sep 2016, 04:03AM PDT, and is ongoing in the Brawley Seismic Zone near the southern terminus of the San Andreas Fault and about 12 km (7.5 mi) north of Salton Buttes. The swarm does not appear to be related to volcanic activity. The USGS/Caltech Southern California Seismic Network has identified 37 events as of 9:10 AM PDT today with magnitudes ranging between M1.4 to M4.3 at 4 to 9 km depth. Two two previous swarms occurred in the area in 2009 and 2001. See the full report and updates.