Research Directed Toward the Use of Long and Intermediate Period Seismic Waves for the Identification of Seismic Sources
Semi-annual technical rept. no. 6, Jan-Jun 1974
LAMONT-DOHERTY GEOLOGICAL OBSERVATORY PALISADES NY
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The study of anomalous events has succeeded in clarifying many of their puzzling aspects. Careful attention to the details of body wave magnitude computations has markedly reduced the number of anomalous events on the Asian continent. The remaining anomalous events display the same short period surface wave characteristics as intraplate events and because of their focal depth and the continental crustal structure there is the strong likelihood that Love wave surface magnitudes will provide a good discriminant. The propagation of Love waves from one layered structure to another has been solved by a very efficient computational method giving excellent agreement with observations. A new technique of analyzing multi-mode surface wave dispersion has been developed which makes it possible to separate fundamental and higher mode Love waves from earth quake sources, given many observations. The technique permits mapping the horizontal variations of Love wave phase velocities. The relation of earthquake focal mechanisms to global tectonic patterns has been extended to include the heretofore perplexing plate boundaries in the South Atlantic.