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Source parameters of the 1989 Loma Prieta Earthquake determined from long‐period Rayleigh waves
Author(s) -
Zhang Jiajun,
Lay Thorne
Publication year - 1990
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/gl017i008p01195
Subject(s) - rayleigh wave , seismology , geology , period (music) , surface wave , centroid , seismic wave , geodesy , optics , physics , geometry , acoustics , mathematics
The source parameters of the Loma Prieta earthquake are determined using long‐period Rayleigh waves recorded by USGS/ERIS, IDA/IRIS, and GEOSCOPE stations. The source mechanism is well‐constrained by the Rayleigh wave radiation pattern, with a dip = 70 (±5)°, strike = 130 (±5)°, rake = 135 (±5)°, and moment = 3.4 (±0.5) × 10 19 Nm (M w = 7.0). This mechanism is generally consistent with independent body wave determinations. The most stable long‐period waves, with periods from 200 to 275 s, indicate that the source process has a centroid time of about 10 s, somewhat longer than that indicated by body waves (about 5–6 s). This discrepancy cannot be uniquely attributed to source effects because of uncertainties in the propagation corrections. The importance of using surface waves with short propagation paths for analysis of moderate size earthquakes such as the Loma Prieta event is demonstrated by the unreasonably long source durations inferred from R 3 arrivals.