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Interactions between Landers and Hector Mine, California, earthquakes from space geodesy, boundary element modeling, and time-dependent friction

Evelyn J. Price and Roland Buergmann
Interactions between Landers and Hector Mine, California, earthquakes from space geodesy, boundary element modeling, and time-dependent friction (in The Hector Mine, California, earthquake of 16 October 1999, Michael J. Rymer (editor), Victoria E. Langenheim (editor) and Egill Hauksson (editor))
Bulletin of the Seismological Society of America (May 2002) 92 (4): 1450-1469

Abstract

The M (sub W) 7.1 Hector Mine earthquake happened 7 years after the 1992 M (sub W) 7.3 Landers earthquake, within a system of right-lateral strike slip faults comprising the Eastern California Shear Zone. Because estimates of recurrence intervals of M 7 earthquakes on these faults range anywhere from 1500 to 50,000 years, the close temporal spacing of these two earthquakes suggests that there is some interaction between the two. Current models of simple Coulomb static stress interactions between the earthquake ruptures do not predict an obvious cause-and-effect relationship. The interaction between the computed normal and right-lateral shear stress reductions induced by the Landers earthquake at the Hector Mine hypocenter is unclear. We use a combination of space geodesy, boundary element modeling, and computer modeling of time-dependent fault friction to investigate the interaction between the two earthquakes. We compare stress changes on the Hector Mine rupture plane induced by the Landers earthquake with the detailed slip distribution inferred using a combination of GPS and InSAR data. The slip distributions of both earthquakes are also used to infer the magnitude of the shear stress drop on each earthquake rupture and the orientation of the remote background stress consistent with these two recent events. For each earthquake the azimuth of the remote maximum compressive stress was approximately 17 degrees + or -6 degrees , and the magnitude of the shear stress drop was 8+ or -1 MPa on the Landers rupture and 10+ or -2 MPa on the Hector Mine rupture. Using a simple spring-and-slider model as a proxy for the rate-and-state frictional response of the Hector Mine faults to Landers earthquake-imposed stress steps, we find that, while a decrease in normal stress at the Hector Mine hypocenter would, by itself, have caused the Hector Mine earthquake to nucleate immediately, the simultaneous decrease in shear stress may have caused a delay in the peak shear loading. Consideration of an acceptable range of rate-and-state friction parameters, secular strain rates, and crustal stiffnesses leads us to conclude that this delay could have been 0 to 40 years.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 92
Serial Issue: 4
Title: Interactions between Landers and Hector Mine, California, earthquakes from space geodesy, boundary element modeling, and time-dependent friction
Title: The Hector Mine, California, earthquake of 16 October 1999
Author(s): Price, Evelyn J.Buergmann, Roland
Author(s): Rymer, Michael J.editor
Author(s): Langenheim, Victoria E.editor
Author(s): Hauksson, Egilleditor
Affiliation: University of Alaska at Fairbanks, Geophysical Institute, Fairbanks, AK, United States
Affiliation: U. S. Geological Survey, Menlo Park, CA, United States
Pages: 1450-1469
Published: 200205
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 85
Accession Number: 2002-064946
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, geol. sketch maps
N34°00'00" - N35°00'00", W117°00'00" - W116°00'00"
Secondary Affiliation: California Institute of Technology, USA, United StatesUniversity of California at Berkeley, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200220
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