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Time‐space variation of seismic S‐wave coda attenuation (Q c −1 ) and magnitude distribution (b‐values) for the Petatlan Earthquake
Author(s) -
NoveloCasanova D. A.,
Berg E.,
Hsu V.,
Helsley C. E.
Publication year - 1985
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/gl012i011p00789
Subject(s) - aftershock , coda , seismology , foreshock , geology , magnitude (astronomy) , asperity (geotechnical engineering) , attenuation , variation (astronomy) , geodesy , physics , astrophysics , optics , geotechnical engineering
Average S‐wave coda‐Q (Q c ) at 6 Hz and to about 10 sec after the S‐wave arrival shows: (1) temporal variation positively correlated with the magnitude distribution parameter b for foreshocks and aftershocks of the 1979 Petatlan, Mexico earthquake; (2) spatial variation through the aftershock area, positively correlated with b, high Q c ‐b values at the two activity centers, intermediate values in between and landward, and low values toward the Middle America Trench, which remain low for two weeks after the main shock; and (3) five‐foreshock average Q c = 135±1.6% and eleven‐aftershock average Q c = 175±1.3% for the eastern asperity. The b values—and possibly Q c values—seem to correlate with the level of aftershock activity.