Cross-power and coherency as a function of period and azimuth have been calculated for several seismic stations during the course of a microseismic storm in the north Pacific. These data indicate that in addition to the predicted Rayleigh waves, a large fraction of the observed ground motion must be due to other wave types, most of which have predominantly vertical motion. The data indicate that the angle subtended by the source of the waves increases with distance, suggesting that wave interactions at the coastline may be a major factor in the observed disturbances on the continent.

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