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.
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.
A picture is worth a thousand words—USGS Post Doctoral Fellow Jared Peacock's new 3D geophysical model for the Long Valley Caldera and Mammoth Mountain reveals a subsurface marked by active hydrothermal reservoirs (hot water and fluids), bodies of partial melt (molten rock), and rock that has been pervasively altered to clay by fluids from a now extinct hydrothermal reservoir. Using magnetotelluric (MT) data, Jared located a robust hydrothermal reservoir with a source located about 4 km (2 and a half miles) under Deer Mountain. Groundwater heated in this reservoir flows upward and eastward towards the caldera's Resurgent Dome. A separate hydrothermal reservoir was identified under Mammoth Mountain at a depth of about 1 km (0.6 mi). Both reservoirs are fueled by heat emanating from small bodies of partially molten rock located more than 8 km (5 mi) below the surface. The new model verifies and improves upon the results of earlier geophysical investigations.
A newly released geologic map and U.S. Geological Survey Professional Paper, Eruptive History of Mammoth Mountain and its Mafic Periphery, California, by CalVO scientists Wes Hildreth and Judith Fierstein recount the geologic and volcanic history of the area east of the Sierra Nevada in greater detail than any previously published report. The map includes the Long Valley Caldera, Mono-Inyo chain, Mammoth Mountain and the Middle Fork canyon of the San Joaquin River, including Devils Postpile National Monument.
Geophysical unrest beneath the Mammoth Mountain volcano, and in adjacent parts of the Sierra Nevada and Long Valley Caldera, has generated some concern among residents, stakeholders, and geoscientists since at least 1980 when four magnitude-6 earthquakes shook the area. Three decades of volcano monitoring near Mammoth Mountain has documented numerous earthquake swarms, ground deformation, and emission of magmatic carbon dioxide gas . The new map and publication contribute detailed information to scientists' understanding of the eruption frequency and volcanic history of the area, which is essential for assessing the region's likely long-term future volcanic activity.
The new map and report represent a significant milestone after decades of geologic fieldwork and research. The release of the map and report coincides with the 2016 celebration of the 100th anniversary of the establishment of the National Park Service. In the month of July, staff from the USGS, Devils Postpile National Monument and Inyo National Forest have teamed up to offer outdoor educational activities for the public as the new map and report are unveiled. CalVO geologists Wes Hildreth, Judy Fierstein, and others will be hosting an interpretive talk at Minaret Vista Overlook near the monument on July 14. They will also lead an interpretive hike to the Devils Postpile formation and to nearby Rainbow Falls, both in the monument, on July 15. If you plan to visit Devils Postpile National Monument this week, be sure to check out these great opportunities to hear about the volcanic history of the area from expert geologists!