Seismic wave propagation and earthquake characteristics in Asia

The effects of subduction zones on local and teleseismic network data for earthquakes in the North Pacific have been determined. Hypocenter location, focal mechanisms and slip vectors are all perturbed in ways that can be corrected by tracing seismic rays through appropriate models of the upper mantle. The matching of synthetic seismograms for the first 30 seconds of the long period P signal with observations at several azimuths yields depths of crustal events to within 10 km and reliable estimates of focal mechanisms and source time functions. Spectral estimates for body waves based on the autocorrelation function, with a Hanning window, are more reliable than those by the FFT algorithm. Station spectra can be corrected reasonably well for source crust and receiver crust effects, but the proper way to model attenuation remains a difficult problem. The use of a frequency-dependent modulation of T/Q has been tested and seems promising.