Time functions appropriate for some aftershocks of the Point Mugu, California earthquake of February 21, 1973
Broad-band recordings of aftershocks of the Pt. Mugu earthquake at small epicentral distances provided an excellent opportunity to test source models for small earthquakes. Simple events recorded at nearly vertical incidence produced a single P-wave pulse of a duration of about 0.07 sec and a somewhat more complicated S wave with a slightly longer duration. Such events are consistent with a point dislocation source for which Q_β = 100 or for which there is directivity with the fault breaking downward. We attribute the more usual complexities of small earthquake records to multiple events, some of which we observed, layering effects combined with greater epicentral distances, and scattering.
Additional InformationCopyright © 1975, by the Seismological Society of America. Manuscript received June 7, 1974. The authors were assisted by Francis Lehner, Len Blayney, John Lower, and Dan Tanner in the data collection and in the detailed synthesis of the system response. This research was supported by the Advanced Research Projects Agency of the Department of Defense and was monitored by the Air Force Office of Scientific Research under Contract FF44620-72 C-0083.
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