A Least-Squares Procedure for Direct Estimation of Azimuth and Velocity of a Propagating Wave,

摘要

A least-squares technique for the estimation of the phase velocity and apparent azimuth of a plane wave propagating across a horizontal array is developed and applied to two events:the Rayleigh waves from an Alaskan earthquake recorded on the 7-element UBO long-period seismic array,and the acoustic-gravity waves from a presumed atmospheric nuclear explosion,recorded on part of the 13-element microbarographic array at LAMA. Both time-domain and frequency-domain formulations of the technique were used, i.e.,both the multichannel correlation and spectral matrices are used to measure the interchannel time shifts. The results suggest that the time-domain application may provide a useful algorithm for signal detection. The phase velocity dispersion results in both cases agree reasonably well with theory and with group velocities calculated by another method. Prewhitening (Flattening the spectral peaks by linear filtering) was tested as a means of preventing spectral leakage from contaminating the derived phase velocity and azimuth;the results suggest that prewhitening decreases the standard error when the signal-to-noise ratio is high,but is ineffective when the signal-to-noise ratio is low. (Author)