Introduction

We present a new approach to develop and evaluate earth models at the regional scale that utilizes full waveform seismograms. Adequate path calibrations are crucial for improving the accuracy of seismic event location and origin time, size, and mechanism. There is considerable information on structure in broadband seismograms that is currently not utilized. The limitations have been largely theoretical. The development and application to solid earth problems of powerful numerical techniques, such as the Spectral Element Method (SEM), has opened a new era, and it should be possible to compute the complete predicted wavefield accurately without any restrictions on the strength or spatial extent of heterogeneity. This approach requires considerable computational power, which is currently not fully reachable in practice.

We have begun work on an approach which relies on a cascade of increasingly accurate theoretical approximations for the computation of the seismic wavefield to develop a model of structure for the area of Eurasia located between longitudes of 30 and 150 degrees E, and latitudes of -10 to 60 degrees North. The selected area is particularly suitable for the purpose of this experiment, as it is highly heterogeneous, presenting a challenge for modeling, but it is well surrounded by earthquake sources and a significant number of high quality broadband digital stations exist, for which data are readily accessible through IRIS (Incorporated Research Institutions for Seismology) and the FDSN (Federation of Digital Seismic Networks).

Berkeley Seismological Laboratory
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