Accession Number : ADA292944

Title :   Investigation of the Transportability of the P/S Ratio Discriminant to Different Tectonic Regions.

Corporate Author : ENSCO INC SPRINGFIELD VA SIGNAL ANALYSIS SYSTEMS DIV

Personal Author(s) : Baumgardt, Douglas ; Der, Zoltan

PDF Url : ADA292944

Report Date : 06 DEC 1994

Pagination or Media Count : 75

Abstract : We have developed, analyzed, and contrasted two methods for correcting measurements of Pn/Sn and NLg ratio for distance in the Scandinavian shield, the first based on an earlier detection study of Sereno and the second method has been developed specifically for regions of sparse station coverage. Both methods provide smooth distance correction curves which can correct amplitude ratio measurements to a standard distance. However, we have observed large scatter in the observations of Pn/Sn and Pn/Lg ratios as a function of distance, and the distance correction curves are not well constrained. Crustal cross sections of propagation paths in three different tectonic regions, have been derived from on-line GIS databases, and we have found approximate correlations of high-frequency Pn/Lg amplitude ratio with the crustal parameters of average elevation, average depth to basement (sediment thickness), and gradients in these parameters. Using these correlations and comparing Pn/Lg ratio measurements of a Chinese nuclear explosion with blasts in eastern Europe and Scandinavia, we find that Pn/Lg ratios in the Scandinavian shield need to be decreased by nearly 0.8 log units when comparing them to events in tectonically active regions like China. Similar analyses can be used for transporting discriminants in the future to other tectonically active regions, such as the Middle East. (AN)

Descriptors :   *SEISMIC DISCRIMINATION, *TECTONICS, DATA BASES, NUCLEAR EXPLOSIONS, PARAMETERS, COMPARISON, TIME SERIES ANALYSIS, DEPTH, REGRESSION ANALYSIS, SEISMIC DATA, CORRELATION, WAVE PROPAGATION, CROSS SECTIONS, EARTH CRUST, SEISMIC WAVES, BLAST LOADS, EARTHQUAKES, ELEVATION, RANGE(DISTANCE), AMPLITUDE, SEDIMENTS, STRUCTURAL GEOLOGY, SEISMOGRAPHS.

Subject Categories : Soil Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE