Open AccessComment on ‘Q for short‐period P waves: is it frequency dependent?’ by A. Douglas
Author(s) -
Murphy John R.
Publication year - 1993
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1993.tb00906.x
Subject(s) - seismology , geology , period (music) , deconvolution , source model , amplitude , test site , yield (engineering) , seismic wave , spectral line , physics , computational physics , optics , astronomy , acoustics , thermodynamics
SUMMARY Douglas (1992) has presented evidence based on deconvolution analyses of British array data recorded from explosions at the Shagan River Test Site (STS), USSR and the Nevada Test Site (NTS), USA from which he has concluded that the source time dependence characteristics of explosions at these test sites is significantly different from that associated with the Mueller‐Murphy (M‐M) seismic source model. The objective of this note is to demonstrate that the M‐M model is in fact consistent with a very large variety of short‐period P ‐wave observations from explosions and to argue that the alternate source time function proposed by Douglas (1992) is inconsistent with both theoretical and observational constraints on the explosion source process. More specifically, network‐averaged teleseismic P ‐wave spectra corresponding to NTS, French Sahara and STS explosions in granite are used to illustrate the fact that the M‐M source model can provide remarkably good descriptions of the observed amplitude levels and spectral shapes over the short‐period band extending from at least 0.5 to 2.5 Hz, as well as seismic estimates of explosion yield which agree very closely with corresponding yield estimates obtained from other, independent sources.