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Source Parameters Of the May 7, 1986 Andreanof Islands Earthquake

Hwang, Lorraine J. and Kanamori, Hiroo (1986) Source Parameters Of the May 7, 1986 Andreanof Islands Earthquake. Geophysical Research Letters, 13 (13). pp. 1426-1429. ISSN 0094-8276. doi:10.1029/GL013i013p01426.

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Source characteristics of the May 7, 1986 Andreanof Islands earthquake (51.412°N, 174.830°W, NEIC) are investigated from WWSSN, GDSN and IDA records. First motions from over 60 stations determine one steeply dipping nodal plane. We constrained this nodal plane and inverted long-period surface waves at a period of T=256 sec and determined the second nodal plane to be dip 18°, rake 116°, and strike 257°. This shallowly dipping thrust mechanism is consistent with plate motions in this region. Seismic moment from surface-wave inversion is 1.3×10^(28) dyne-cm corresponding to M_w=8.0. Amplitudes of body and surface waves from short-period instruments yield magnitudes of equation image and M_s=7.7. The teleseismic average P-wave moment rate spectrum from 17 short- and intermediate-period instruments is slightly lower than that of an average M_w=8.0 subduction-zone event. We constrained the fault plane as determined above to deconvolve the first 90 secs of the long-period body wave at 11 teleseismic stations to determine the source time function and the spatial distribution of moment release. The source time function consists of 4 moment-releasing episodes which have a total moment release of 9.4×10^(27) dyne-cm. The fault ruptured bilaterally with the largest moment releasing subevent occurring between 30-45 sec. This subevent nucleates approximately 75-90 km west of the determined epicenter. This region corresponds to the epicentral area of the 1957 Great Aleutian earthquake which is one of the largest earthquakes in recorded history.

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Kanamori, Hiroo0000-0001-8219-9428
Alternate Title:Of the May 7, 1986 Andreanof Islands Earthquake source parameters
Additional Information:Copyright 1986 by the American Geophysical Union. (Received October 6, 1986; accepted October 22, 1986.) Paper number 6L7064. We thank the personnel from the WWSSN stations, Project IDA at the Institute for Geophysics and Planetary Physics at University of California, San Diego and the U.S. Geological Survey for making their data available to us. H. Houston helped us with the computation of the source spectra. Thoughtful reviews by L. Astiz and H. Houston were greatly appreciated. This research was supported by USGS Grant No. 14-08-0001-G1170 and partially by an NSF Graduate Fellowship. Contribution No. 4407, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125. Lorraine J. Hwang and Hiroo Kanamori (1987) Correction to “Source parameters of the May 7, 1986 Andreanof Islands Earthquake”. Geophysical Research Letters Volume 14, Issue 2, page 170, February 1987 DOI: 10.1029/GL014i002p00170
Group:Division of Geological and Planetary Sciences
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NSF Graduate Research FellowshipUNSPECIFIED
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Caltech Division of Geological and Planetary Sciences4407
Issue or Number:13
Record Number:CaltechAUTHORS:20141030-102856627
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51056
Deposited By: George Porter
Deposited On:30 Oct 2014 17:44
Last Modified:01 Jun 2023 22:49

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