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Comparison of strong-motion spectra with teleseismic spectra for three magnitude 8 subduction-zone earthquakes

Houston, Heidi and Kanamori, Hiroo (1990) Comparison of strong-motion spectra with teleseismic spectra for three magnitude 8 subduction-zone earthquakes. Bulletin of the Seismological Society of America, 80 (4). pp. 913-934. ISSN 0037-1106. https://resolver.caltech.edu/CaltechAUTHORS:20140806-111823869

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Abstract

We studied strong-motion spectra observed for three M_w 7.8 to 8.0 earthquakes (the 1985 Michoacán, Mexico; 1985 Valparaíso, Chile; and 1983 Akita-Oki, Japan earthquakes). We determined the decay of spectral amplitude with distance from the station, considering different measures of distance from a finite fault. We compared strong-motion spectra (Fourier acceleration spectra) observed for these three earthquakes with those estimated from the source spectrum determined from teleseismic P waves. We scaled the teleseismic source spectra to produce reference strong-motion spectra at periods from 1 to 10 sec using a simple physical model of far-field S body waves from a point source recorded at the surface of a homogeneous half-space. For all three earthquakes the reference spectral amplitudes at periods of 1 to 5 sec are about half the observed ones at distances of about 50 km. The difference increases as the distance increases. At distances of 200 to 300 km, the reference spectrum is about 1/10 of the observed one. The difference between the reference and the observed spectrum is attributed to the contribution of phases other than direct S waves and to site response. We applied corrections for the finiteness (spatial extent) of the source using a simple model of rupture propagation on a dipping two-dimensional fault. Including the source finiteness did not improve the estimate substantially at periods from 1 to 20 sec, but it modeled significant changes in the signal duration as a function of azimuth for the 1985 Michoacán earthquake. Our results can be used to establish empirical relations between the observed spectra and the half-space responses, depending on the distance and the site condition. If such empirical relations can be established, source spectra determined from teleseismic records may be used to estimate strong motions.


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http://bssa.geoscienceworld.org/content/80/4/913.abstractPublisherArticle
Additional Information:© 1990, by the Seismological Society of America. Manuscript received 30 May 1989. Accelerograms from the Guerrero accelerometer array were made available by John Anderson and the Institute of Geophysics and Planetary Physics of the University of California, San Diego and the Instituto de Ingenieria at the Universidad Nacional Autonoma de Mexico, Mexico City. T. Sato provided strong-motion data from the Akita-Oki earthquake, which were used with the permission of the Port and Harbor Research Institute (stations AKI, AOM, HAK, SAK, MUR, and HAC), the Central Research Institute of the Electric Power Industry (stations FRF and SRN), and Hirosaki University (station HRD). E. Kausel provided strong-motion data from the Valparaiso earthquake recorded by accelerometers operated by the Department of Geophysics at the University of Chile. P. Mork, M. Celebi, and G. H. Saragoni made available strong-motion data from accelerometers operated by the Department of Civil Engineering at the University of Chile. The paper was reviewed by D. Boore and J. Boatwright. This research was partially supported by NSF grants ECE-86-10994 and EAR-87-21190, USGS Grant 14-08-0001-G1773, and the W. M. Keck Foundation. This is contribution No. 90 of the Institute of Tectonics and C. F. Richter Seismological Laboratory.
Funders:
Funding AgencyGrant Number
NSFECE-86-10994
NSFEAR-87-21190
USGS14-08-0001-G1773
W. M. Keck FoundationUNSPECIFIED
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Institute of Tectonics and C. F. Richter Seismological Laboratory90
Issue or Number:4
Record Number:CaltechAUTHORS:20140806-111823869
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140806-111823869
Official Citation:Heidi Houston and Hiroo Kanamori Comparison of strong-motion spectra with teleseismic spectra for three magnitude 8 subduction-zone earthquakes Bulletin of the Seismological Society of America, August 1990, v. 80, p. 913-934
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48076
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:06 Aug 2014 18:35
Last Modified:03 Oct 2019 06:59

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