Evidence of Spall from Deghosting of Short-Period Teleseisms
TELEDYNE GEOTECH ALEXANDRIA VA SEISMIC DATA ANALYSIS CENTER
Pagination or Media Count:
Spall signals, if present on teleseisms, should be most easily detected in the short-period P-waveforms. If pP and spall P sub s echoes are identical in waveform to the P then, theoretically, deghosting filters could remove these source echoes and produce identical seismograms from neighboring explosions with nearly identical source-to-receiver paths. If P sub s is absent, the pP corrections alone suffice. Determining the optimum echo amplitude and delay parameters involves trial-and-error and using known event depths and close-in measurements of pP and P sub s echo delays when available. Two explosions at Pahute Mesa, KNICKERBOCKER in 1967 and CHATEAUGAY in 1968, which were within 25 meters of the same depth and within 0.5 kilometers of the same location, generated virtually identical seismograms at all stations their correlation coefficient exceeded 0.95 at RKON. For other neighboring pairs of Pahute Mesa explosions correlation coefficients ranged between 0.50 and 0.70.