Narrow and Broad Region Dispersion of Long-Period Surface Waves
Technical rept. no. 16
TEXAS INSTRUMENTS INC DALLAS EQUIPMENT GROUP
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Examples of both narrow and broad region dispersion analysis for long-period surface waves are presented. Narrow region dispersion analysis of KurilesKamchatka earthquake signals recorded at Guam, by means of moving-window maximum entropy spectral analysis, indicates strong multipathing in the 3.0 to 4.5 kmsec group velocity range, causing poor polarization filter performance. In contrast, between 2.0 and 3.0 kmsec the signals are well defined, resulting in a good polarization filter response. The dispersion for this region seems quite diverse. Broad region dispersion models for the North American and Asian continents were generated using previously reported group velocity data for Nevada Test Site and Eastern Kazakh presumed nuclear explosion signals recorded at world-wide stations. These models facilitate frequency-dependent surface wave magnitude measurement.