Waveform tomography of a complex model of the lithosphere with two-dimensional, full wavefield, visco-elastic, wide-angle, synthetic seismic data.

摘要

A third-party realistic synthetic seismic dataset was created for use in a blind experiment. The data were created in a geological model 250 km long and 40 km deep, representative of a section of continental lithosphere with heterogeneous P-velocity, S-velocity, density and Q-factor. The 2-D, visco-elastic, wide-angle data were generated using 51 shots spaced every 5 km, and 2779 receivers, spaced every 90 m.; Following the successful blind test, a carefully selected subset of the available data frequencies, avoiding spectral redundancy in the image, was used to recover equivalent results with a significant decrease in total computational cost. In wide-angle experiments, the cost of dense spatial sampling of the wavefield is prohibitive. Low-frequency data are also difficult to acquire. The effects of increased receiver spacings, increased source spacings, and increased starting frequencies were therefore investigated. We found the required source sampling wavenumber to avoid aliasing in the tomography image was greater than or equal to kNyq/3, where k Nyq is the Nyquist sampling wavenumber; this condition requires that the receiver sampling wavenumber exceeds kNyq. In tests of the starting frequency, good quality images of the central portion of the model were obtained for starting frequencies as large as 3.0 Hz.; These results suggest waveform tomography can be performed with wide-angle data without requiring dense spatial sampling of the wavefield in both recording domains. (Abstract shortened by UMI.)