Studies of Regional Body and Surface Waves in Eastern Asia - Data Analysis and Modeling
STATE UNIV OF NEW YORK AT BUFFALO DEPT OF GEOLOGICAL SCIENCES
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This report consists of two parts. The first consists of a surface wave regionalization and tomographic analysis of China. The second involves modeling of regional body waveforms from earthquakes in western China. Love and Rayleigh waves recorded at CDSN stations for earthquakes within China and on its periphery are used to determine dispersion along more than 400 paths in China and its immediate vicinity. These data are used to determine the dispersion characteristics of 17 regions, which may then be inverted for velocity structure. We have also attempted to determine the anisotropic nature of the crust and upper mantle of this area. However, at present, the data is not sufficient to resolve the additional parameters. Regional body waves have been collected and modeled from a profile of earthquakes located southwest of CDSN station WMQ. The profile is compared to a profile of synthetic seismograms computed using a frequency-wavenumber integration technique with an assumed velocity structure model. Since the depths of the different earthquakes varies, we also compare individual P waveforms with synthetics computed for 10, 20 and 30 km depth. The variable moveout of different phases within the P sub n-P sub g wavetrain enables a fairly accurate determination of source depth. This illustrates that the interference of phases that contribute to the regional P sub n-P sub g waveforms can serve as a discriminant.