The Effect of Bandwidth Limitations on the Inference of Slip-Weakening and Energy Parameters from Seismograms
Abstract
Numerous researchers have obtained estimates of slip-weakening distance Dc and fracture energy for recent earthquakes. Dc is often observed to be a significant fraction of the total slip and tends to correlate with total slip. While these observations may well be true of real earthquakes, we show that low-pass filtering of strong motion seismograms can also produce some of these effects in inverted rupture models. We test the accuracy of Dc estimates by calculating them in 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 Dc for model B is about twice that for model A. By low-pass filtering slip models A and B at 1.0 Hz, we simulate the blurring effects of band-limited waveform inversions on these slip models. At each point on a fault, Dc' is defined to be the slip at the time of the peak slip speed at that point. Low-pass filtering the slip models causes an upward bias in Dc inferred from stress-slip curves, and it causes an artificial correlation between Dc' and the total slip. Low-pass filtering might also bias fracture energy high and radiated energy low. These biases should be considered when interpreting Dc derived from band-limited slip models of real earthquakes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2004
- Bibcode:
- 2004AGUFM.T22A..04S
- Keywords:
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- 7209 Earthquake dynamics and mechanics