Review of the U.S. Geological Survey's Volcano Hazards Program (2000) / Chapter Skim
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6 A Vision for the USGS Volcano Hazards Program
6 A Vision for the USGS Volcano Hazards Program
Pages 93-102
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From page 93... ...
AN ALTERNATE SCENARIO FOR THE 2010 ERUPTION OF MOUNT RAINIER The first sign that Mount Rainier was reawakening came from crustal deformation measurements at the CVO. A dense array of permanent GPS receivers in the area picked up subtle ground movements nearly a year before the eruption.
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From page 94... ...
Field mapping, combined with subsurface imaging using ground penetrating radar and shallow seismic methods, allowed the hazard assessment team to develop complete three-dimensional maps of deposits from past eruptions, debris flows, and landslides and to assemble detailed
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From page 95... ...
The three-dimensional mapping combined with accurate dating and dramatically improved models of volcanic eruption processes allowed the team to assign probabilistic estimates for impending eruption scenarios. The scientist in charge was thus able to update the likelihood of these scenarios in near real time, as monitoring data from satellites and remote locations on the volcano streamed into the observatory.
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From page 96... ...
During this time, a university team brought in an array of absolute gravity meters, capable of measuring the earth's gravitational force with an accuracy of ~ part in 100 million. They detected a slight increase in the gravity field that, when combined with the GPS, InSAR, seismic, and electromagnetic imaging results, helped constrain estimates of the density and composition of the magma.
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From page 97... ...
Acoustic flow monitors, which detect the ground vibrations due to fast-moving mudflows, were double-checked, and people in the path of possible mudflows were alerted and evacuation procedures reviewed. These models and monitoring devices had been developed in part based on sophisticated studies of debris flows using a large-scale experimental facility designed and run by USGS VHP scientists.
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From page 98... ...
Sophisticated source modeling helped seismologists locate constrictions in the magma conduit that caused pressure increases followed by episodic discharges of magma. Shortly thereafter, the first recordings of harmonic tremor, a low-frequency oscillation detected by seismic instruments, were reported.
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From page 99... ...
Disaster preparedness planning was well advanced. The Washington State Emergency Management Agency task force completed a tabletop simulation of the Mount Rainier eruption emergency plan.
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From page 100... ...
Air traffic was diverted away from the region and critical facilities went into automated shutdown procedures. The Air National Guard was called in to deploy a widely dispersed network of relatively inexpensive, casehardened, biodegradable microsensors capable of detecting and relaying, via satellite, ambient temperature, pressure, humidity, and geochemical conditions to recording stations tens of kilometers away.
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From page 101... ...
Property damage, however, exceeded several billion dollars. As the eruption progressed through the night, VHP staff focused on forecasting rates of ash accumulation in nearby communities, continued lahar hazards, and the probable duration of the eruption.
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