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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

Cooling, degassing and compaction of rhyolitic ash flow tuffs: A computational model Cooling, degassing and compaction of rhyolitic ash flow tuffs: A computational model

Previous models of degassing, cooling and compaction of rhyolitic ash flow deposits are combined in a single computational model that runs on a personal computer. The model applies to a broader range of initial and boundary conditions than Riehle's earlier model, which did not integrate heat and mass flux with compaction and which for compound units was limited to two deposits. Model...
Authors
J.R. Riehle, T.F. Miller, R. A. Bailey

Factors influencing the height of Hawaiian lava fountains: implications for the use of fountain height as an indicator of magma gas content Factors influencing the height of Hawaiian lava fountains: implications for the use of fountain height as an indicator of magma gas content

The heights of lava fountains formed in Hawaiian-style eruptions are controlled by magma gas content, volume flux and the amounts of lava re-entrainment and gas bubble coalescence. Theoretical models of lava fountaining are used to analyse data on lava fountain height variations collected during the 1983–1986 Pu'u 'O'o vent of Kilauea volcano, Hawaii. The results show that the variable...
Authors
E.A. Parfitt, L. Wilson, C.A. Neal

Volcano seismology, hazards assessment Volcano seismology, hazards assessment

The last few years have seen several impressive examples of seismic monitoring at volcanoes to provide warnings that have saved lives and property. Changes in the rates and character of volcanic earthquakes provided precursory signs to explosive eruptions of moderate size at Redoubt volcano (Alaska), Mount Unzen (Japan), Mount Spurr (Alaska), and Rabaul caldera (Papua New Guinea), as...
Authors
J. Mori

Thermodynamics of gas and steam-blast eruptions Thermodynamics of gas and steam-blast eruptions

Eruptions of gas or steam and non-juvenile debris are common in volcanic and hydrothermal areas. From reports of non-juvenile eruptions or eruptive sequences world-wide, at least three types (or end-members) can be identified: (1) those involving rock and liquid water initially at boiling-point temperatures (‘boiling-point eruptions’); (2) those powered by gas (primarily water vapor) at...
Authors
L.G. Mastin
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