Kinematic earthquake rupture inversion in the frequency domain

Abstract

We develop a frequency-based approach to earthquake slip inversion that requires no priorinformation on the rupture velocity or slip-rate functions. Because the inversion is linear andis performed separately at each frequency, it is computationally efficient and suited to imagingthe finest resolvable spatial details of rupture. We demonstrate the approach on syntheticseismograms based on the Source Inversion Validation Exercise 1 (SIV1) of a crustal Mw 6.6strike-slip earthquake recorded locally. A robust inversion approach is obtained by applyinga combination of damping, smoothing and forcing zero slip at the edge of the fault model.This approach achieves reasonable data fits, overall agreement to the SIV1 model, includingslip-rate functions of each subfault, from which its total slip, slip time history and rupturevelocity can be extracted.We demonstrate the method's robustness by exploring the effects ofnoise, random timing errors, and fault geometry errors. The worst effects on the inversion areseen from errors in the assumed fault geometry.