Conference Papers

The magnitude 6. 1 Morgan Hill, California, earthquake of April 24, 1984, produced a set of acceleration records at the freeway overpass in San Jose carrying I-280/I-680 across U. S. 101, 12 km from the epicenter. Peak accelerations reached 0. 10 g at ground level and 0. 16 g in the box girder. The integrated displacements at frequencies higher than 3 Hz permit the identification of the

Multiple generations of prehistoric sand blows, interpreted as earthquake induced, have been discovered throughout coastal South Carolina. These sand blows extend far beyond 1886 earthquake induced sand blows, in sediments having approximately the same liquefaction susceptibility. The seismic source zone for the prehistoric sand blows is unknown. The different distributions of...

Hydrodynamics of the upper extent of the Potomac Estuary between Indian Head and Morgantown, Md. , are simulated using a two-dimensional model. The model computes water-surface elevations and depth-averaged velocities by numerically integrating finite-difference forms of the equations of mass and momentum conservation using the alternating direction implicit method. The fundamental, non...

No abstract available

Changes in salinity and nitrate concentration in groundwater and surface water in the semiarid Arkansas River valley of southeastern Colorado, USA were related primarily to irrigation practices. Water is applied to fields by flood irrigation through ditches and furrows. Irrigation water is derived in nearly equal amounts from surface water and groundwater pumped from the shallow alluvial...

The collapse of the north face of Mount St. Helens on May 18, 1980, and the debris avalanche that resulted blocked outflow from Spirit Lake and Coldwater and South Fork Castle Creeks. Spirit Lake began to increase in size and lakes began to form in the canyons of Coldwater and South Fork Castle Creeks. Coldwater and Castle Lakes would have overtopped their respective blockages in late...

In this paper the authors describe an experimental research program, conducted in conjunction with the National Acidic Precipitation Assessment Program (NAPAP), to quantify acid-rain damage to commercial and cultural carbonate-rock resources. Initial results of this experiment show that carbonate-rock dissolution and associated surface recession increase with increasing acid deposition...

The Charleston, South Carolina, area offers a unique opportunity to conduct studies that give insight into the implementation of policy for long-term earthquake preparedness at the local level. Research by Greene and Gori documented the low state of preparedness in 1981. Recent studies show that earthquake preparedness activities are now occurring in Charleston. Since 1981, increased...

MAPGEN is a software system that facilitates production of cartographic displays in the research and production environment. The system generates a set of metagraphic overlays of application-defined geographical information that can be aggregated in any combination for display without reprocessing the original data. An overview of the control files, available cartographic projections...

In 1984, the U.S. Geological Survey conducted a detailed geologic analysis of two nuclear test craters at Enewetak Atoll, Marshall Islands, on behalf of the Defense Nuclear Agency. A multidisciplinary task force mapped the morphology, surface character, and subsurface structure of two craters, OAK and KOA. The field mapping techniques include echo sounding, sidescan sonar imaging, single...

Thirteen natural frequencies of a concrete arch dam (Monticello Dam near Sacramento, California) have been identified by using a dynamic testing method which employs an air gun firing in the reservoir as the excitation source. These vibrations modes are determined from the peak responses in the Fourier amplitude spectra of the free-vibration data recorded at three crest locations using...

No abstract available