HR: 1330h
AN: S42C-0187    [PDF]
TI: Tests of the Accuracy of the {\it Dc'} Estimate of Earthquake Slip-Weakening Distance
AU: * Spudich, P
EM: spudich@usgs.gov
AF: U. S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Guatteri, M
EM: Mariagiovanna_Guatteri@swissre.com
AF: Swiss Re, 175 King St., Armonk, NY 10504 United States
AB: Mikumo {\it et al.} (2003) and Fukuyama {\it et al.} (2003) have proposed a parameter they call {\it Dc'} which might be a useful estimate of slip weakening distance {\it Dc}. At each point on a fault, {\it Dc'} is defined to be the slip at the time of the peak slip speed at that point. We test the accuracy of the {\it Dc'} estimate by calculating it in unfiltered and low-pass filtered versions of models A and B of Guatteri and Spudich (2000). Models A and B are two different rupture models for a hypothetical M6.5 earthquake, and they have nearly identical rupture time, slip, and stress drop distributions, as well as nearly identical predicted seismograms, but {\it Dc'} for model B is about twice that for model A. {\it Dc'} calculated for these models tends to underestimate {\it Dc}. By low-pass filtering slip models A and B at 1.0 Hz or 0.2 Hz, we simulate the blurring effects, on these slip models, of band-limited waveform inversions. In these filtered slip models, {\it Dc'} usually overestimates {\it Dc} for subfaults in which {\it Dc} is less than half the total slip, but {\it Dc'} is approximately correct for subfaults having {\it Dc} greater than half the total slip. Low-pass filtering the slip models causes an artificial correlation between {\it Dc'} and the total slip. Spatial variations of {\it Dc'} in filtered slip models do not necessarily correlate with spatial variations of {\it Dc}. These biases should be considered when interpreting {\it Dc'} derived from band-limited slip models of real earthquakes.
DE: 7209 Earthquake dynamics and mechanics
DE: 7215 Earthquake parameters
SC: Seismology [S]
MN: 2003 Fall Meeting