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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Focal mechanisms for eastern Tennessee earthquakes, 1981-1983

Teague, Alan Gaither January 1984 (has links)
To understand better the faulting process in the Southern Appalachians, eleven single event focal mechanisms (SEFM) and seven composite focal mechanisms (CFM) are determined from 37 events that occurred in eastern Tennessee between September 1981 and July 1983. Both P-wave polarities and (Sv/P)z amplitude ratios are input to a computer program that systematically searches the focal sphere for solutions acceptable within pre-set error limits. Hypocenter locations, azimuth and departure angles are taken from locations obtained by the Tennessee Earthquake Information Center (TEIG) with a four layer velocity model (GCOl). A second velocity model (STEP2), developed to improve focal depth estimates and to acquire continuously varying departure angles, is used to relocate events for which SEFM and CFM solutions are obtained. The two different velocity models produced focal mechanisms with similar nodal plane and P-axis orientations, indicating stable and reliable results; the differences between average strike, dip, and rake angles of the two data sets range from 2° to 11°. Both SEFM and CFM solutions exhibit predominantly strike-slip motion along nearly vertical north-south (right-lateral) or east-west (left-lateral) oriented nodal planes. Standard deviations for average strike, dip, and rake angles are generally less than 20°. P-axis trends average about N50°E, with a nearly horizontal average plunge, and both have standard deviations of 25° or less. Except for three events in the northernmost region, all earthquakes in the study area result from a maximum compressive stress trending between N40°E and N70°E and plunging between 10° and -30°. / Master of Science

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