Regional Network: Seismicity of Asia: and Frequency-Dependent Q.
Final rept. 1 Feb 85-30 Sep 86,
COLUMBIA UNIV NEW YORK
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A method is developed for the computation of body-wave synthetics which is suitable to a medium having smooth variation with depth and anelasticity having arbitrary variation with frequency. The method is applied to an anelastic earth model where Q is assumed to follow a power-law frequency dependence. The outcome is a pulse shape with properties quite different from what might be expected if the familiar constant-Q pulse shapes are surveyed. The seismicity of Soviet Central Asia is studied using Soviet catalogs, and the relationship between topography and seismicity is analyzed using digital terrain data. The seismicity is concentrated along the major topographic gradients dividing the distinct physiographictectonic provinces of the region, with relatively low activity in both high plateaus and low basins and higher activity along the flanks of mountainous areas. Further, there is a distinct relationship between seismic activity and active salt diapirism. The capabilities of the New York State Seismic Array for studying teleseismic waveforms and sub-array structure are evaluated.