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The effects of site response on source parameters deduced for the 1980 Long Valley, California earthquake sequence
Author(s) -
Peppin William A.
Publication year - 1991
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/91gl02080
Subject(s) - seismogram , geology , seismometer , seismology , seismic moment , cutoff frequency , sequence (biology) , displacement (psychology) , geodesy , physics , fault (geology) , optics , biology , genetics , psychology , psychotherapist
Data taken from the University of Nevada (UNR) array of surface‐located wideband, digital, displacement seismographs placed over the 1980 Long Valley earthquake sequence show very strong site effects, which control spectral parameters and hence inferred source parameters, up to M L 5.0. Observations from 4,000 seismograms show that differences in site effects can lead to inferred seismic moments at least a factor of two lower than previously reported. Observed S‐wave spectral corner frequencies show upper‐bound cutoffs which are widely disparate at different sites (e.g., 15 Hz at MG1 and 6 Hz at WT1), thus f max is quite variable by site. This high‐ frequency cutoff, clearly a site effect at WT1, could be misinterpreted as an apparent departure from source similarity for seismic moments below 10 21 dyn‐cm. Estimates of seismic moment and source duration from the UNR ‘rock’ sites may be more accurate than those previously published, both because the UNR instrumentation has greater resolution at longer periods (0.1 to 1.0 Hz) and because of less near‐site signal distortion at high frequencies.