Suture Zones, Seismic Wave Propagation, and Tectonics of Central Asia

Abstract : Some of the results of a number of projects are summarized: An approximate method for calculating the reflection and transmission coefficients of obliquely incident Rayleigh waves across two welded quarter-spaces is outlined; Group velocities of fundamental mode Rayleigh and Love waves, with paths traversing the Tibetan Plateau, were used to determine that the Tibetan Plateau has a 70 km thick crust, with a low velocity zone at an intermediate level within the crust; A zone of large, negative residuals for P-wave arrivals exists in northern New York State. Surface-wave amplitude spectra constrained by body-wave first motions are sufficient to determine focal mechanisms for some moderate-sized earthquakes along the Mid-Atlantic ridge; Microseismicity and geological evidences were used to model the current tectonic processes of the Hazara district in northern Pakistan; The historical and modern seismicity of a portion of south-central Asia was compiled and critically reviewed to delineate large-scale seismotectonic trends; and Seismic, volcanic, and plate tectonic data indicate the Makran region of southern Pakistan is an active subduction zone.