A comparison of broadband source spectra, seismic energies, and stress drops of the 1989 Loma Prieta and 1988 Armenian earthquakes
- Univ. of California, Santa Cruz (USA)
Broadband source spectra of the 1989 Loma Prieta (M{sub W} = 6.9) and 1988 Armenian (M{sub W} = 6.7) earthquakes are computed at periods from 1 to 50 sec using digitally-recorded teleseismic P body waves. The effects of attenuation, geometrical spreading, and radiation pattern are removed from the spectra of individual stations, which are then averaged. The source spectra of the Loma Prieta and Armenian earthquakes are higher for their seismic moments than the spectra of 11 intraplate earthquakes studied by Zhuo and Kanamori (1987), which in turn are 2 to 4 times larger than average spectra of interplate subduction zone earthquakes. The seismically radiated energy can be computed from the source spectrum using Haskell's (1964) formulation assuming a point source with no directivity. An Orowan stress drop can be obtained from the seismic energy and moment. The Orowan stress drops for the Loma Prieta and Armenian earthquakes are both about 20 bars, significantly higher than Orowan stress drops of recent large interplate earthquakes. There is a positive correlation between the Orowan stress drops and the estimated repeat times, consistent with the notion that mechanical fault strength increases with increasing interseismic period.
- OSTI ID:
- 6400561
- Journal Information:
- Geophysical Research Letters (American Geophysical Union); (USA), Journal Name: Geophysical Research Letters (American Geophysical Union); (USA) Vol. 17:9; ISSN GPRLA; ISSN 0094-8276
- Country of Publication:
- United States
- Language:
- English
Similar Records
Broadband source spectrum, seismic energy, and stress drop of the 1989 Macquarie Ridge earthquake
Seismic slip, segmentation, and the Loma Prieta earthquake
Related Subjects
580000* -- Geosciences
ASIA
ATTENUATION
CALIFORNIA
COMPARATIVE EVALUATIONS
DATA ANALYSIS
EARTHQUAKE MAGNITUDE
EARTHQUAKES
EASTERN EUROPE
EUROPE
FEDERAL REGION IX
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
NORTH AMERICA
SEISMIC EVENTS
SEISMIC P WAVES
SEISMIC SOURCES
SEISMIC WAVES
SLIP
STRESS ANALYSIS
USA
USSR