Publications

Seismic events have long been known to cause changes in the level of oceans, streams, lakes, and the water table. The great San Francisco earthquake of 1906 induced significant hydrologic changes that were qualitatively similar to those changes observed for the Loma Prieta earthquake. What is different is that the hydrologic data sets collected from the Loma Prieta event have enough...

No abstract available.

Supply of 210Pb to the continental shelf off the northeastern United States is dominated by the deposition from the atmosphere, the rate of which is reliably known from previously published work. Excess 210Pb inventories in the shelf sediments show accumulations that are nearly in balance with the supply, even in areas of relict sands where it is believed that no net accumulation of...

During the 1969-1974 Mauna Ulu eruption on Kilauea's upper east rift zone, lava tubes were observed to develop by four principal processes: (1) flat, rooted crusts grew across streams within confined channels; (2) overflows and spatter accreted to levees to build arched roofs across streams; (3) plates of solidified crust floating downstream coalesced to form a roof; and (4) pahoehoe...

The character of the vesicle population in lava flows includes several measurable parameters that may provide important constraints on lava flow dynamics and rheology. Interpretation of vesicle size distributions (VSDs), however, requires an understanding of vesiculation processes in feeder conduits, and of post-eruption modifications to VSDs during transport and emplacement. To this end...

A critical need exists among coastal researchers and policy-makers for a precise method to obtain shoreline positions from historical maps and aerial photographs. A number of methods that vary widely in approach and accuracy have been developed to meet this need. None of the existing methods, however, address the entire range of cartographic and photogrammetric techniques required for...

Magmatic fluids, both vapour and hypersaline liquid, are a primary source of many components in hydrothermal ore deposits formed in volcanic arcs. These components, including metals and their ligands, become concentrated in magmas in various ways from various sources, including subducted oceanic crust. Leaching of rocks also contributes components to the hydrothermal fluid—a process...

The catastrophic release of gas from Lake Nyos, Cameroon, in 1986 caused substantial but incomplete mixing of the stratified water column. The post-release evolution of water-column structure has been monitored through April 1992. Changes began immediately after the event as rainfall and inflow brought dilute fluid into the surface layer. Inflow and surface mixing have gradually deepened...

Quaternary volcanoes of the Cascade Range form a 1,200- kilometer-long arc that extends from southern British Columbia to northern California. The section of the Cascade Range volcanic arc in central Oregon is characterized by relatively high Quaternary volcanic extrusion rates and hot-spring discharge rates. Stableisotope data and measurements of hot-spring heat discharge indicate that...

Multibeam bathymetry and seismic reflection profiles of the New Jersey continental slope reveal a series of abandoned and now-buried submarine canyons that have apparently influenced the development of modern canyons. The buried canyons are infilled along nine slope-wide unconformities separating upper-middle Miocene to Pleistocene sediments that thin downslope. Canyons infilled during...

New seismic reflection data from Chesapeake Bay reveal a buried, 85-km-wide, 1.5-2.0-km-deep, peak-ring impact crater, carved through upper Eocene to Lower Cretaceous sedimentary strata and into underlying pre-Mesozoic crystalline basement rocks. A polymictic, late Eocene impact breccia, composed mainly of locally derived sedimentary debris (determined from four continuous cores)...

Seismic profiling data indicate that the thickness of an accreted oceanic terrane of Paleocene and early Eocene age, which forms the basement of much of the forearc beneath western Oregon and Washington, varies by approximately a factor of 4 along the strike of the Cascadia subduction zone. Beneath the Oregon Coast Range, the accreted terrane is 25 to 35 kilometers thick, whereas...