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Teleseismic source parameters and rupture characteristics of the 24 November 1987, Superstition Hills earthquake

Hwang, Lorraine J. and Magistrale, Harold and Kanamori, Hiroo (1990) Teleseismic source parameters and rupture characteristics of the 24 November 1987, Superstition Hills earthquake. Bulletin of the Seismological Society of America, 80 (1). pp. 43-56. ISSN 0037-1106. https://resolver.caltech.edu/CaltechAUTHORS:20140813-134940334

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Abstract

Long-period body waves from the 24 November 1987, Superstition Hills earthquake are studied to determine the focal mechanism and spatial extent of the seismic source. The earthquake is a complex event consisting of two spatially distinct subevents with different focal mechanisms. Two consistent models of rupture are developed. For both models, the second subevent begins 8 sec after the initiation of the first subevent and the preferred centroid depth lies between 4 to 8 km. Model 1 consists of two point sources separated by 15 to 20 km along strike of the Superstition Hills fault. Model 2 consists of one point source and one line source with a rupture velocity of 2.5 km/sec with moment release distributed along strike of the focal plane at a distance of 10 to 22 km from the epicenter. These moment release patterns show that a significant amount of long-period energy is radiated from the southern segment of the fault. Total moment release for both models is approximately 8 × 10^(25) dyne-cm. Both models also suggest a change of dip from near vertical near the epicenter to steeply southwesterly dipping along the southern segment of the fault. The difference in rupture characteristics and fault dips seen teleseismically is also reflected in aftershock and afterslip data, and crustal structure underlying the two fault segments. The northern segment had more aftershocks and a smaller proportion of afterslip than the southern segment. The boundary between the two segments lies at a step in the basement that separates a deeper metasedimentary basement to the south from a shallower crystalline basement to the north.


Item Type:Article
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http://bssa.geoscienceworld.org/content/80/1/43.abstractPublisherArticle
Additional Information:© 1990, by the Seismological Society of America. Manuscript received 21 July 1989. We thank the personnel at the WWSSN, CAND and USGS for making the data available to us. A. Bent and D. Wald reviewed a previous version of this manuscript for us. T. Heaton solved our timing problem by suggesting the use of the Borrego Mountain earthquake. Numerous discussions with D. Heimberger and T. Heaton were helpful. This work was supported by an NSF Graduate Fellowship, NSF Grant EAR-86-18189 and the USGS under contract 14-08-001-G1356 and 14-08-001-G1354. Contribution No. 4773, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California.
Funders:
Funding AgencyGrant Number
NSF Graduate FellowshipUNSPECIFIED
NSFEAR-86-18189
USGS14-08-001-G1356
USGS14-08-001-G1354
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Caltech Division of Geological and Planetary Sciences4773
Issue or Number:1
Record Number:CaltechAUTHORS:20140813-134940334
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140813-134940334
Official Citation:Lorraine J. Hwang, Harold Magistrale, and Hiroo Kanamori Teleseismic source parameters and rupture characteristics of the 24 November 1987, Superstition Hills earthquake Bulletin of the Seismological Society of America, February 1990, v. 80, p. 43-56
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48522
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:13 Aug 2014 21:04
Last Modified:03 Oct 2019 07:04

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