Dept. of Geophysics Colloquium: Illuminating the Dynamic Effect of Fault Geometry on Earthquake Ruptures with Lab Experiments

Zoom: https://tau-ac-il.zoom.us/j/85032703038

Abstract:

Long tectonic faults typically exhibit non-planar geometry across multiple scales, which is suggested to strongly affect the dynamics and destructive potential of earthquake ruptures. However, due to limited direct observations, the exact effect of fault geometry on rupture behavior remains unclear. Here, we experimentally mimic earthquake ruptures and combine ultrahigh-speed cinematography and image analysis to resolve the full-field evolution of dynamics associated with rupture propagation. By controlling the experimental fault geometry, we test the effect of simple bends as well as complex multiscale roughness on rupture dynamics. For the rough interfaces, we also measure the off-fault seismic signal with laser vibrometers. I will show how geometric deviations promote complex ruptures, including new and previously unrecognized rupture behaviors, and how they amplify ground motions and acceleration spectra. Lastly, I will present results from a collaboration with Université Côte d’Azur, combining our experimental measurements with an approximate analytical approach to show that fault geometry dominates the slip distribution during earthquakes. These new observations reveal how fault structure influences rupture dynamics, providing critical information for hazard assessment, model calibration, and seismic data interpretation.

Event Organizer: Dr. Lior Rubanenko