Repeating earthquake finite source models: Strong asperities revealed on the San Andreas Fault
Article first published online: 5 DEC 2007
Copyright 2007 by the American Geophysical Union.
Geophysical Research Letters
Volume 34, Issue 23, December 2007
How to Cite
2007), Repeating earthquake finite source models: Strong asperities revealed on the San Andreas Fault, Geophys. Res. Lett., 34, L23302, doi:10.1029/2007GL031353., , and (
- Issue published online: 5 DEC 2007
- Article first published online: 5 DEC 2007
- Manuscript Accepted: 18 OCT 2007
- Manuscript Revised: 10 OCT 2007
- Manuscript Received: 24 JUL 2007
- finite source;
- stress drop;
- fault mechanics
 We investigate the rupture process of a sequence of repeating Mw 2.1 earthquakes on the San Andreas Fault in Parkfield spanning the occurrence of the September 28, 2004 mainshock by inverting seismic moment rate functions obtained from empirical Green's function deconvolution. The results show that these events have extremely concentrated slip patches with radii on the order of 10–20 m, with peak slip between 8.4 and 11.4 cm. The rupture speed and rise time are consistent with values of larger earthquakes. The spatial distribution of stress drop for the events shows low average values 2.5–5.6 MPa and very large peak values of 66.7–93.9 MPa. The results show that strong asperities can exist at small scales on an otherwise weak fault, and helps reconcile differences between traditional spectra-based and tectonic loading methods for determining the stress drop of small repeating earthquakes.