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Alcedo volcano is one of six shield volcanoes on Isabela Island in the western Galápagos Islands. Although Alcedo is dominantiy basaltic, it is unusual in that it also has erupted ∼1 km3 of rhyolite. The rhyolitic phase marked a 10-fold decrease in the mass-eruption rate of the volcano, and the volcano...

Updated radiometric calibration and systematic processing procedures for Galileo solid‐state imaging (SSI) data from the first (1990) Earth‐Moon encounter are presented. These procedures were applied to a whole‐disk imaging sequence of the Moon centered near Mare Orientale, called Lunmap 14 (L14). Processing of L14 data included radiometric calibration, subpixel coregistration,...

Strain accumulation observed over the 1974 to 1988 interval in a 25 by 100 km aperture trilateration network spanning Owens Valley is adequately described by a strain rate that is uniform in space and time. The tensor strain-rate components referred to a coordinate system with the 2 axis directed N18°W...

Uplift as a function of time from 1951 through 1990 has been deduced from annual mean sea level measured at 15 tide gages along the Nankai subduction zone, southwest Japan. The recurrence interval for rupture of the Nankai subduction zone is about 100 years, and the most recent rupture was...

The geochemical processes controlling the behavior of stable Pb, 210Pb, and 210po in seasonally anoxic Lake Sammamish, Washington were identified from water column distributions and box model calculations. Total (sum of dissolved and particulate) inventories of stable Pb, 210Pb, and 210Po increased in the whole lake during the latter part of the oxic stage...

The U.S. Geological Survey, in cooperation with the Kentucky Natural Resources and Environmental Protection Cabinet, constructed a two-dimensional, steady-state ground-water-flow model to estimate hydraulic properties, contributing areas to discharge boundaries, and the average linear velocity at selected locations in an aquifer system near Calvert City, Ky. Nonlinear regression was used...

A two-dimensional, multispecies reactive solute transport model with sequential aerobic and anaerobic degradation processes was developed and tested. The model was used to study the field-scale solute transport and degradation processes at the Bemidji, Minnesota, crude oil spill site. The simulations included the biodegradation of volatile and nonvolatile fractions of...

Rainfall and streamflow data collected in Lake County, Ill., from March 1990 through September 1993 were used to (1) calibrate a rainfall-runoff model for an area encompassing three watersheds (individual areas of 17.2, 35.7, and 37.0 mi2 (square miles) and (2) verify the regional model parameter set obtained from the calibration...

Guemes Island, located in Puget Sound of Washington State, is experiencing population growth and seawater intrusion. The island consists of Pleistocene glacial deposits overlying bedrock. Geologic sections and a map of surficial geology were constructed and used to delineate six hydrogeologic units, three of which are aquifers. The most productive...

To construct a digital simulation of a plume of brackish water in the surficial Biscayne aquifer of central Dade County, Florida, that originated from a flowing artesian well, it was necessary to quantify the rate of spillage and the consequent point-source loading of the aquifer. However, a flow-rate measurement (2,350...

Desert Valley is a 1,200-square-mile, north- trending, structural basin, about 30 miles northwest of Winnemucca, Nevada. Unconsolidated basin-fill deposits exceeding 7,000 feet in thickness constitute the primary ground-water reservoir. Dewatering operations at an open-pit mine began in the Spring of 1985 in the northeast part of Desert Valley. Ground-water withdrawal...

Channel change and suspended-sediment transport were monitored in the Salt and Hassayampa Rivers in Maricopa County, Arizona, during the winter and summer rainy seasons of 1991-92. Flows were moderate. Results illustrate the high instability of these channels and high variability of process and response. A channelized, gravel-paved reach of...

A study was done to describe the hydrogeology of unconsolidated deposits, simulated ground-water flow, and ground-water quality at two landfills in Bristol, Vermont. The study area is characterized by a glacial delta greater than 200 feet thick on the west flank of the Green Mountains. An upper unconfined, coarse-grained glacial...

The assimilative capacities of selected reaches of the Waccamaw River and the Atlantic Intracoastal Waterway near Myrtle Beach, South Carolina, were determined using results from water-quality simulations by the Branched Lagrangian Transport Model. The study area included tidally influenced sections of the Waccamaw River, the Pee Dee River, Bull Creek,...

In 1991 the Trinity River Basin study unit was among the first 20 study units in which work began under full-scale program implementation of the National Water-Quality Assessment Program. A retrospective assessment was undertaken to review and analyze existing pesticide data and related environmental factors. Population and land-use data indicate...

Three aquifers and two confining units have been delineated within the drift underlying the area near the site of a former coal-tar distillation and wood-preserving plant in St. Louis Park, Minnesota. The hydrogeologic units of the drift, in descending order, are the upper drift aquifer, the upper drift confining unit,...

Disposal of munitions and chemical-warfare substances has introduced inorganic and organic contaminants to the ground water, surface water, and bottom sediment at O-Field, in the Edgewood area of Aberdeen Proving Ground, Maryland. Contaminants include chloride, arsenic, transition metals, chlorinated aliphatic hydrocarbons, aromatic compounds, and organosulfur and organophosphorus compounds. The hydrologic...

The 250-square mile study area in southwestern King County, Washington is underlain by sediments as much as 2,200 feet thick, deposited during at least four continental glacial/interglacial periods. Published surficial geologic maps and drillers' lithologic logs from about 700 field-located wells were used to prepare 28 geologic sections; these sections...

A statewide study of flood magnitude and frequency in urban areas of Georgia was made to develop methods of estimating flood characteristics at ungaged urban sites. A knowledge of the magnitude and frequency of floods is needed for the design of highway drainage structures, establishing flood- insurance rates, and other...

The 72 basins of the 82,000-square-mile study area were grouped into five broad categories on the basis of their geohydrologic characteristics. Water-resources development has resulted in depletion of surface flow in several basins and overdraft of ground water in most developed basins. In places, water levels have declined more than...

Calf Creek Spring provides drinking water to users of Calf Creek Campground, which is operated by the Bureau of Land Management in southcentral Utah. Use of all methods and tools available indicates that surface water from Calf Creek does not contribute to the discharge of Calf Creek Spring.Microscopic Particulate Analysis...

The hydrogeology of Hardee and De Soto Counties in west-central Florida was evaluated, and a ground-water flow model was developed to simulate the effects of expected increases in ground-water withdrawals for citrus irrigation on the potentiometric surfaces of the intermediate aquifer system and the Upper Floridan aquifer. In 1988, total...

In this paper, we report on an experiment aimed at evaluating the feasibility of the application of our coupled regional climate modeling system to long-term climate simulations over the Great Lakes region. The simulation analyzed covers a continuous 24-month period beginning 1 September 1990 and extending to 1 September 1992.Many...

The possible effects of trace-gas induced climatic changes on Pyramid and Yellowstone Lakes are assessed using a model of lake temperature. The model is driven by 312">312 years of hourly meteorological data obtained directly from the output of double-CO2 experiments (2 × CO2) conducted with a regional...