P and PKP CODA Decay Characteristics for Earthquakes

Abstract : P and PKP coda characteristics are determined for earthquakes from 15 seismic regions as recorded at 17 World Wide Standard Seismograph Stations (WWSSS). In determining the coda characteristics for an event, amplitude measurements, scaled relative to the largest excursion in the coda, are made in successive time windows, and the coda envelope obtained by connecting successive observations. The individual coda, average coda, and standard deviations about the average coda as a function of time into the coda (in units of m(b)) are given for each set of measurements. The coda for events individual coda, average coda, and standard deviations about the average coda as a function of time into the coda (in units of m(b)) are given for each set of measurements. The coda for events in a given region recorded at a given distance are found to be very similar to the coda for events from another region recorded at the same distance. That is, coda characteristics are determined primarily by the arrival times and amplitude of significant secondary phases.