scholarly journals Compilation of results of three-dimensional stress determinations made in Rainier and Aqueduct Mesas, Nevada Test Site, Nevada

1980 ◽  
Author(s):  
William L. Ellis ◽  
Jerry E. Magner
1978 ◽  
Vol 68 (2) ◽  
pp. 451-469
Author(s):  
Walter W. Hays

Abstract Ground-response maps for Tonopah, Nevada, were prepared using ground-motion data from a Nevada Test Site explosion recorded on a 12-station seismic array in Tonopah. These data were used to define 10 frequency-dependent ground-response maps for the period range 0.05 to 2.5 sec. These data were combined with the probabilistic calculation of earthquake ground accelerations on rock sites in the Tonopah area, made in a 1976 study by S. T. Algermissen and D. M. Perkins, in order to give estimates of the ground shaking expected throughout the city in a 50-yr period of time, at the 90 per cent probability level. Although these relative ground-response estimates are based on low-strain data, they provide a preliminary basis for delineating geographic areas with different susceptibilities to earthquake ground shaking until the time that high-strain earthquake ground-motion measurements become available in Tonopah.


1984 ◽  
Vol 74 (6) ◽  
pp. 2187-2199
Author(s):  
Jing Wen ◽  
George A. McMechan

Abstract Three-dimensional kinematic migration produces a “best-fit” migrated surface, in three-dimensions, of any chosen reflector. The data are the travel times of all observed reflections and diffractions produced by the reflector. Source/receiver configurations are arbitrary, but should be arranged to provide good spatial sampling of the reflector. Each observation contributes an ellipsoid containing all possible reflection points. From this family of ellipsoids, the optimal reflector surface (the envelope of the family) is estimated by use of a statistical imaging condition. The “best-fit” position and shape of the reflector surface is obtained by defining a regular (x, y) grid over the region of interest and estimating the reflector depth beneath each grid point from the distribution of ellipsoids that are present there. The imaging criterion is implemented at each grid point by convolution of a Gaussian with the vector of ellipsoid depths. The width of the Gaussian is chosen to correspond to the scale of the features one wishes to resolve in the image. For each grid point, the migrated image is located at the depth at which the convolution is a maximum. The algorithm is applied to both synthetic and real data. The synthetic data are constructed by ray tracing in a known structure. The real data are from a seismic survey at the Nevada Test Site; here, a reflector is imaged and interpreted as the surface of a high velocity Paleozoic dolomite that is overlain by low-velocity tuffs.


Geophysics ◽  
1962 ◽  
Vol 27 (5) ◽  
pp. 599-610 ◽  
Author(s):  
John W. Allingham ◽  
Isidore Zietz

A granitic stock at Oak Spring, Nevada, was selected in 1960 by the Atomic Energy Commission as a possible site to study the seismic effect of a deep nuclear shot contained in a large volume of rock. Geophysical surveys were conducted to determine the general configuration of the stock, particularly the thickness. The stock intrudes a sequence of carbonate and siliceous sedimentary rocks of Paleozoic age, which are overlain by Tertiary pyroclastic rocks consisting of tuff, welded tuff, and breccia. A three‐dimensional analysis of a detailed aeromagnetic survey indicates that the stock has a shape similar to a truncated cone, the diameter of which increases from about one mile at the surface to at least 6 miles near sea level, 5,000 feet beneath the surface. The stock, therefore, is much larger than indicated by the area of [Formula: see text] square miles exposed at the surface. In addition, computations show that the intrusion has a thickness of at least 13,000 ft. Much of the ambiguity of interpretation was removed from the analysis because susceptibility measurements of cores from recent drilling and remanent magnetization data from surface samples were available. Interpretation of a gravity profile over the stock gives the probable thickness of the overlying alluvial fill and buried tuff, but does not delineate the intrusive from the Paleozoic rocks.


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