Effect of Asymmetric Topography on Rupture Propagation Along Fault Stepovers
Description:
Complex fault systems are often located in regions with asymmetric topography, and these systems are very common in Southern California. As an example, the eastern portion of the left-lateral Garlock fault system, which is composed of two segments separated by an extensional stepover width of 3-4 km, has high mountain ranges on its northern side and almost a flat topography on the southern side. Previous rupture dynamic studies have investigated the effect of stepover widths on throughgoing rupture but these stepover studies assumed a flat topography and didn’t examine the influence of topography on the rupture behavior. Therefore, in this study, to investigate the effect of topography, I consider three cases: a flat topography, a positive (mountain) and a negative (basin) topography on only one side of the fault system outside of the stepover. In each case, I consider a suite of geometries with two 30 km long vertical planar segments with 5 km overlap and stepover widths of 2 to 8 km. I create a three-dimensional finite element mesh for each of those geometries and use FaultMod to compute the rupture dynamics. The results show a significant time dependent variation of the normal stress for the topography cases as opposed to the flat surface case. For a positive topography on the right of the rupture propagation for a left-lateral fault, there is a clamping effect behind the rupture front that prevents the rupture to jump a wider extensional stepover. The opposite is observed for a negative topography or positive topography on the left side of the rupture propagation, where the rupture can jump over a wider stepover than the flat case. These results suggest that topography seems to have significant impact on throughgoing rupture and should be considered in dynamic studies with geometric complexities such as stepovers, bends and branch fault systems.
Session: Numerical Modeling in Seismology: Developments and Applications
Type: Oral
Date: 4/20/2023
Presentation Time: 03:00 PM (local time)
Presenting Author: Roby Douilly
Student Presenter: No
Invited Presentation:
Authors
Roby Douilly Presenting Author Corresponding Author roby.douilly@ucr.edu University of California, Riverside |
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Effect of Asymmetric Topography on Rupture Propagation Along Fault Stepovers
Category
Numerical Modeling in Seismology: Developments and Applications