Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published May 2002 | Published
Journal Article Open

Source Description of the 1999 Hector Mine, California, Earthquake, Part II: Complexity of Slip History


We present a rupture model of the Hector Mine earthquake (M 7.1), determined from the joint inversion of strong-motion records, P and SH teleseismic body waves, Global Positioning System (GPS) displacement vectors, and measured surface offset. We solve for variable local slip, rake angle, rise time, and rupture velocity of a finite-fault model involving multiple segments. The inversion methodology developed in a companion article (Ji et al., 2002) combines a wavelet transform approach with a nonlinear (simulated annealing) algorithm. The final model is checked by forward simulating the Interferometric Synthetic Aperture Radar (InSar) data. Our estimation to the seismic moment is 6.28 × 10^(19) N m, which is distributed along three segments from north to south, releasing 37%, 41%, and 22% of the total moment, respectively. The average slip is 1.5 m, with peak amplitudes as high as 7 m. The fault rupture has an average rise time of 3.5 sec and a relatively slow average rupture velocity (1.9 km/sec) resulting in a 14-sec rupture propagation history. Our approach permits large variation in rupture velocity and rise time, and indicates that rise time appears to be roughly proportional to slip and shorter rise times are associated with the initiation of asperity rupture. We also find evidence for nearly simultaneous rupture of the two northern branches.

Additional Information

© 2002 by the Seismological Society of America. Manuscript received 6 November 2000. We benefited from discussions with H. Kanamori. We thank M. Simons for providing the InSar figure, E. Hauksson for the aftershock catalog, and D. Agnew for the GPS data. The manuscript benefited significantly from the thoughtful comments by the reviewers S. H. Hartzell, G. C. Beroza, and associate editor V. Langenheim. This project was supported by SCEC Contract Number. NSF EAR-8920136 and by the U.S. Geological Survey under Contract Number 1HQGR0098. The figures were made using GMT (Generic Mapping Tools) software (Wessel and Smith, 1991). This is Contribution Number 8750, Division of Geological and Planetary Sciences, California Institute of Technology.

Attached Files

Published - 1208.full.pdf


Files (6.0 MB)
Name Size Download all
6.0 MB Preview Download

Additional details

August 19, 2023
October 20, 2023