Mechanics, Slip Behavior, and Seismic Potential of Corrugated Dip Slip Faults

Scott T. Marshall, & Anna C. Morris

Published March 2012, SCEC Contribution #1497

To better understand the mechanics and seismic potential of non-planar fault surfaces, we present results from a suite of numerical models of faults with sinusoidal corrugations in the down-dip direction. Systematic variations in corrugation wavelength, amplitude, and loading angle are introduced to determine the effects on slip behavior and seismic energy release. We find that corrugated faults, in general, slip less than planar faults. Changes in slip behavior are scale independent and correlate to the amplitude/wavelength of corrugations. Model results suggest that obliquely loaded corrugated faults accumulate less strike-slip than a planar fault with the same tip line dimensions and average orientation. This result implies that slip direction is not a reliable indicator of regional stress direction and may at least partially explain repeated nearly pure dip slip coseismic events at oblique plate boundaries. Though seismic energy release can be larger for some corrugated fault surfaces due to a larger surface area, for geologically reasonable corrugation geometries, changes in total seismic energy release are not significantly different than planar faults. Techniques that utilize highly simplified fault geometries may therefore accurately reproduce seismic energy release, but nonetheless incorrectly predict coseismic slip rates and distributions.

Marshall, S. T., & Morris, A. C. (2012). Mechanics, Slip Behavior, and Seismic Potential of Corrugated Dip Slip Faults. Journal of Geophysical Research, 117(B3), B03403. doi: 10.1029/2011JB008642.