2 Matching Results

Search Results

Advanced search parameters have been applied.

Verification of inferred faults by resistivity analysis. Technical progress report, July 17-October 31, 1981

Description: The major purpose of this effort is to detect new faults which may indicate fracture systems with potential for gas production from the black shales. The method is to gather surface geophysical data, principally resistivity, to test Landsat lineaments as faults. A second purpose is to develop an economical method of confirming remotely sensed lineaments as faults or fractures which can be applied in this region and perhaps be extended to the eastern part of the United States. To attain the goal of this work, the planned approach was to use high-powered (3KW) resistivity measurements in a dipole-dipole configuration to penetrate deeply - a rather expensive procedure. Toward this end it was decided to make a preliminary investigation using a scintillation counter in addition to a low-current resistivity measuring instrument. The scintillation counter gave more definite indication of known faults than did the resistivity measurements. The South Graham, North Graham, and the fault at Highways 403-269, Kentucky were all indicated on one traverse by scintillation measurements, but only the North Graham fault was indicated by resistivity, and the resistivities profile was not conclusive. The reason for the inconclusive resistivity result may have been the fact that the fault zones in this region are often thin, sometimes a matter of a few inches.
Date: January 1, 1981
Creator: Jackson, P.L.
Partner: UNT Libraries Government Documents Department

Probablilistic evaluation of earthquake detection and location capability for Illinois, Indiana, Kentucky, Ohio, and West Virginia

Description: Probabilistic estimations of earthquake detection and location capabilities for the states of Illinois, Indiana, Kentucky, Ohio and West Virginia are presented in this document. The algorithm used in these epicentrality and minimum-magnitude estimations is a version of the program NETWORTH by Wirth, Blandford, and Husted (DARPA Order No. 2551, 1978) which was modified for local array evaluation at the University of Michigan Seismological Observatory. Estimations of earthquake detection capability for the years 1970 and 1980 are presented in four regional minimum m/sub b/ magnitude contour maps. Regional 90% confidence error ellipsoids are included for m/sub b/ magnitude events from 2.0 through 5.0 at 0.5 m/sub b/ unit increments. The close agreement between these predicted epicentral 90% confidence estimates and the calculated error ellipses associated with actual earthquakes within the studied region suggest that these error determinations can be used to estimate the reliability of epicenter location. 8 refs., 14 figs., 2 tabs.
Date: September 1, 1980
Creator: Mauk, F.J. & Christensen, D.H.
Partner: UNT Libraries Government Documents Department