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Roof-rock contamination of magma along the top of the reservoir for the Bishop Tuff Roof-rock contamination of magma along the top of the reservoir for the Bishop Tuff

The Bishop Tuff, a Quaternary high-silica rhyolite in east-central California, is widely considered the type example of a vertically and monotonically zoned pyroclastic deposit that represents zoning in the source magma reservoir, inverted during the process of pyroclastic emplacement. However, the deposit of plinian pumice, which forms the base of the Bishop Tuff and represents the...
Authors
W. A. Duffield, J. Ruiz, J.D. Webster

Frequent outburst floods from South Tahoma Glacier, Mount Rainier, USA: Relation to debris flows, meteorological origin, and implications for subglacial hydrology Frequent outburst floods from South Tahoma Glacier, Mount Rainier, USA: Relation to debris flows, meteorological origin, and implications for subglacial hydrology

Destructive debris flows occur frequently at glacierized Mount Rainier volcano, Washington, U.S.A. Twenty-three such flows have occurred in the Tahoma Creek valley since 1967. Hydrologic and geomorphic evidence indicate that all or nearly all of these flows began as outburst floods from South Tahoma Glacier. Flood waters are stored subglacially. The volume of stored water discharged...
Authors
J. S. Walder, C. L. Driedger

San Andreas fault zone drilling project: scientific objectives and technological challenges San Andreas fault zone drilling project: scientific objectives and technological challenges

We are leading a new international initiative to conduct scientific drilling within the San Andreas fault zone at depths of up to 10 km. This project is motivated by the need to understand the physical and chemical processes operating within the fault zone and to answer fundamental questions about earthquake generation along major plate-boundary faults. Through a comprehensive program of...
Authors
S.H. Hickman, L.W. Younker, Mark D. Zoback

The USGS/OFDA Volcano Disaster Assistance Program The USGS/OFDA Volcano Disaster Assistance Program

An erupting volcano is one of nature's truly spectacular sights. From a distance, or perhaps through the cameras of the news media, we often observe roiling mushroom clouds of ash or flows of incandescent lava issuing from the volcano's throat. If, however, you happen to live near that erupting volcano, your life or livelihood may be endangered and your property at risk of destruction a...
Authors
J.W. Ewert, C.D. Miller

Inclusions in Mount St. Helens dacite erupted from 1980 through 1983 Inclusions in Mount St. Helens dacite erupted from 1980 through 1983

Inclusions of plutonic, metavolcanic and volcanic rocks are abundant in dacite pumice and lava from the 1980–1986 eruption sequence at Mount St. Helens. Point counts of inclusions exposed in talus blocks from the dome from 1980 through 1983 show that inclusions form approximately 3.5 vol% of the lava. Eighty-five percent of the inclusions are medium-grained gabbros with an average...
Authors
C. Heliker
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