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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

Decadal and annual changes in biogenic opal and carbonate fluxes to the deep Sargasso Sea Decadal and annual changes in biogenic opal and carbonate fluxes to the deep Sargasso Sea

Analyses of samples from a 14-year series of sediment-trap deployments in the deep Sargasso Sea reveal a significant trend in the ratio of the sinking fluxes of biogenic calcium carbonate and silica. Although there are pronounced seasonal cycles for both flux components, the overall opal/CaCO3 ratio changed by 50% from 1978 to 1991 (largely due to a decrease of opal flux), while total...
Authors
W.G. Deuser, T.D. Jickells, Judith A. Commeau

Pay a little now, or a lot later Pay a little now, or a lot later

Odds are 2-in-3 that at least one disastrous earthquake will strike the San Francisco Bay Area before 2020. Faced with this threat, corporations and government agencies have stepped up efforts that will reduce future losses by billions of dollars.
Authors
William H. Bakun

Seismic maps foster landmark legislation Seismic maps foster landmark legislation

When a powerful earthquake strikes an urban region, damage concentrates not only near the quake's source. Damage can also occur many miles from the source in areas of soft ground. In recent years, scientists have developed ways to identify and map these areas of high seismic hazard. This advance has spurred pioneering legislation to reduce earthquake losses in areas of greatest hazard.
Authors
Roger D. Borcherdt, Robert B. Brown, Robert A. Page, Carl M. Wentworth, James W. Hendley
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