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Modeling Topography and Fault Geometry Effects on Earthquake Ruptures and Ground Motions Along Double Compressional Bends

Description: 

Fault geometry is known for affecting the endpoints of earthquake ruptures. Recent studies suggest that ground surface topography also affects earthquake ruptures and ground motion, but they do not offer much physical explanations. This project is a dynamic rupture modeling geometrical parameter study that explores the effects of fault geometry and topography on earthquake ruptures and ground motion on double compressional bends in strike-slip faults. Our primary variables are fault bend angles, and mountain height and width. Our results show that bend angle has a larger role in controlling earthquake ruptures than topography does. For bend angles >= 23°, earthquakes stop within the linking segment, while faults with bend angles =< 22° ruptured entirely, regardless of topography. Higher or lower initial stresses shift this transition point by only 2° and 1°, respectively. Mountains allow more of the fault to slip compared to the flat models and produce tails and patches of slip along the surface. In models with topography, both supershear and subshear rupture fronts occur. Shallow normal stress perturbations occur at and behind the subshear rupture front, which increase in length and depth for taller and wider mountains and increase in number for narrower ones. Seismic wave reflections within the topography along the linking segment, and associated normal stress perturbations, produce the tails and patches of slip along the surface. This effect is largest when the mountain height is larger than the mountain width. Fault-adjacent topography also increases maximum ground motions in the near field, particularly directly on the hills.

Session: Physics-Based Ground Motion Modeling - II

Type: Oral

Date: 5/3/2024

Presentation Time: 10:30 AM (local time)

Presenting Author: NIcholas

Student Presenter: Yes

Invited Presentation: 

Authors