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Source finiteness of large earthquakes measured from long-period Rayleigh waves

Zhang, Jiajun and Kanamori, Hiroo (1988) Source finiteness of large earthquakes measured from long-period Rayleigh waves. Physics of the Earth and Planetary Interiors, 52 (1-2). pp. 56-84. ISSN 0031-9201. doi:10.1016/0031-9201(88)90057-X.

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The source-finiteness parameters of 11 large shallow earthquakes were determined from long-period Rayleigh waves recorded by the Global Digital Seismograph Network and International Deployment of Accelerometers Networks. The basic data sets are the seismic spectra of periods from 150 to 300 s. In the determination of source-process times, we used Furumoto's phase method and a linear inversion method, in which we simultaneously inverted the spectra and determined the source-process time that minimizes the error in the inversion. These two methods yielded consistent results. The source-process times of the Sumbawa (Indonesia), Colombia-Ecuador, Valparaiso (Chile) and Michoacan (Mexico) earthquakes were estimated to be 79, 118, 69 and 77 s, respectively, from the linear inversion method. The source-process times determined from long-period surface waves were in general longer than those obtained from body waves. Source finiteness of large shallow earthquakes with rupture on a fault plane with a large aspect ratio was modeled with the source-finiteness function introduced by Ben-Menahem. The spectra were inverted to find the extent and direction of the rupture of the earthquake that minimize the error in the inversion. For a rupture velocity of 2.5 km s^(−1), the estimated rupture was unilateral, 100 km long and along the strike, N26°W, for the May 26, 1983 Akita-Oki, Japan earthquake; 165 km and S57°E for the September 19, 1985 Michoacan, Mexico earthquake; 256 km and N31°E for the December 12, 1979 Colombia-Ecuador earthquake; and 149 km and S15°W for the March 3, 1985 Valparaiso, Chile earthquake. The results for the August 19, 1977 Sumbawa, Indonesia earthquake showed that the rupture was bilateral and in the direction N60°E. These results are, in general, consistent with the rupture extent inferred from the aftershock area of these earthquakes.

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Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 1988 Elsevier Science Publishers B.V. Revision accepted June 2, 1987. We thank J.H. Woodhouse and AM. Dziewonski for making available to us coefficients of spherical harmonics for the Model M84C. We also thank J.E. Vidale and L. Astiz for helpful comments on the manuscript. The IDA data used in this study were made available by courtesy of the IDA project team at the Institute of Geophysics and Planetary Physics, University of California, San Diego. This work was supported by NSF grants ECE-83-03647 and EAR-86-07694. Contribution No. 4455, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.
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Caltech Division of Geological and Planetary Sciences4455
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Official Citation:Jiajun Zhang, Hiroo Kanamori, Source finiteness of large earthquakes measured from long-period Rayleigh waves, Physics of the Earth and Planetary Interiors, Volume 52, Issues 1–2, October 1988, Pages 56-84, ISSN 0031-9201, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53959
Deposited By: Tony Diaz
Deposited On:21 Jan 2015 22:47
Last Modified:10 Nov 2021 20:25

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