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Parkfield, California, Earthquake of June 1966: Interpretation of the strong motion records
Author(s) -
ShojaTaheri Jafar
Publication year - 1980
Publication title -
earthquake engineering and structural dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.218
H-Index - 127
eISSN - 1096-9845
pISSN - 0098-8847
DOI - 10.1002/eqe.4290080604
Subject(s) - seismology , geology , fault plane , rayleigh wave , san andreas fault , slip (aerodynamics) , intraplate earthquake , fault (geology) , displacement (psychology) , seismic gap , seismic energy , geodesy , tectonics , surface wave , physics , psychology , astronomy , psychotherapist , thermodynamics
A detailed seismological interpretation of the strong motion records was attempted for the 1966 Parkfield earthquake, California. Velocity and displacement traces integrated from the corresponding recorded accelerograms were found most valuable in studying the earthquake mechanism and wave forms. A double‐couple right‐lateral strike — slip mechanism (along the San Andreas fault) is consistent with the recorded direct S‐waves originating from the hypocentre. High energy arrivals observed on the velocity traces are interpreted as S‐waves (‘stopping phases’) that originated at the termination of the rupture towards the south‐east of the San Andreas fault. A double‐couple left‐lateral strike–slip mechanism is suggested as the cause of this rupture termination. From particle velocity diagrams of the stopping phases in the horizontal plane, the rupture length was found to be between 20 and 28 km. Corresponding rupture velocities are estimated to be 2·5 ± 0·1 and 3·1 ± 0·5 km/s. The inference from the strong motion records is that Love waves were more excited at the south‐western than the north‐eastern side of the fault, whereas the Rayleigh waves were more energetic at the north‐eastern than the south‐western side of the fault.