Improved Procedures for Determining Seismic Source Depths from Depth Phase Information
ENSCO INC SPRINGFIELD VA
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This work has been directed towards evaluating the utility of ENSCOs teleseismic source depth determination procedure as a nuclear discriminant, and also towards simplifying interpretation of the program output. This depth determination procedure, developed during four previous ARPA-sponsored projects, uses cepstrum analysis techniques to detect depth phases, converts delay times to depths using computed travel times, and combines results from different primary phases P,PP,PPP,PcP and stations to get a single depth estimate for an event. Thus, this technique automatically makes use of all available depth phase information in arriving at an estimated depth. Most events were analyzed using the unclassified discrimination experiment data set. This data had very sparse station coverage for almost all events, and it was concluded that this depth determination procedure is not suitable for such a data set. A total of 41 events were examined, but only 18 depth estimates could be made, and most of these were unreliable due to poor station coverage. Some analysis was also done using the complete discrimination experiment data set. This has much better coverage and promises to produce better results.