HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (25) Citing Articles via Google Scholar Google Scholar Articles by Sammis, C. G. Articles by Rice, J. R. Search for Related Content GeoRef GeoRef Citation

Repeating Earthquakes as Low-Stress-Drop Events at a Border between Locked and Creeping Fault Patches

Department of Earth Sciences
University of Southern California
Los Angeles, California, 90089-0740
sammis{at}earth.usc.edu
(C.G.S.)

Department of Earth and Planetary Sciences
and Division of Engineering and Applied Sciences
Harvard University
Cambridge, Massachusetts, 02138
rice{at}esag.harvard.edu.
(J.R.R.)

The source of repeating earthquakes on creeping faults is modeled as a weak asperity at a border between much larger locked and creeping patches on the fault plane. The x^–1/2 decrease in stress concentration with distance x from the boundary is shown to lead directly to the observed scaling TM₀^1/6 between the average repeat time and average scalar moment for a repeating sequence. The stress drop in such small events at the border depends on the size of the large locked patch. For a circular patch of radius R and representative fault parameters, = 7.6(m/R)^3/5 MPa, which yields stress drops between 0.08 and 0.5 MPa (0.8–5 bars) for R between 2 km and 100 m. These low stress drops are consistent with estimates of stress drop for small earthquakes based on their seismic spectra. However, they are orders of magnitude smaller than stress drops calculated under the assumption that repeating sources are isolated stuck asperities on an otherwise creeping fault plane, whose seismic slips keep pace with the surrounding creep rate. Linear streaks of microearthquakes observed on creeping fault planes are trivially explained by the present model as alignments on the boundaries between locked and creeping patches.

This article has been cited by other articles:

				D. C. Templeton, R. M. Nadeau, and R. Burgmann Behavior of Repeating Earthquake Sequences in Central California and the Implications for Subsurface Fault Creep Bulletin of the Seismological Society of America, February 1, 2008; 98(1): 52 - 65. [Abstract] [Full Text] [PDF]

				L. R. Johnson and R. M. Nadeau Asperity Model of an Earthquake: Dynamic Problem Bulletin of the Seismological Society of America, February 1, 2005; 95(1): 75 - 108. [Abstract] [Full Text] [PDF]

				M. Wyss, C. G. Sammis, R. M. Nadeau, and S. Wiemer Fractal Dimension and b-Value on Creeping and Locked Patches of the San Andreas Fault near Parkfield, California Bulletin of the Seismological Society of America, April 1, 2004; 94(2): 410 - 421. [Abstract] [Full Text] [PDF]

				Asperity Models for Earthquakes Bulletin of the Seismological Society of America, August 1, 2003; 93(4): 1792 - 1802.

				Asperity Model of an Earthquake: Static Problem Bulletin of the Seismological Society of America, March 1, 2002; 92(2): 672 - 686.

				A Simple Stick-Slip and Creep-Slip Model for Repeating Earthquakes and its Implication for Microearthquakes at Parkfield Bulletin of the Seismological Society of America, December 1, 2001; 91(6): 1797 - 1804.