Geological Society of America

T60 Earth Surface Processes in Tectonically Active and Unstable Regions II

Sunday, 22 September 2024
1:30 PM - 5:30 PM
210B

THE EFFECT OF GEOMETRICAL COMPLEXITY ON EARTHQUAKE RUPTURE LENGTH

Paper number: T60-13
Program: Technical Sessions
Time: 4:35 PM – 4:55 PM

Authors

Alba Mar Rodriguez Padilla Presenting Author
California Institute of Technology, Pasadena, CA
Michael E. Oskin
University of California, Davis, Davis, CA
Emily E. Brodsky
University of California, Santa Cruz, Santa Cruz, CA
Kelian Dascher-Cousineau
University of California, Berkeley, Berkeley, CA
Vanessa Herrera
San Diego State University, San Diego, CA
Sophia White
University of California, Santa Cruz, Santa Cruz, CA

Abstract

Propagating earthquakes must overcome geometrical complexity on fault networks to grow into large, surface rupturing events. We map step-overs, bends, gaps, splays, and strands of length scales ~100-500 meters from the surface ruptures of 31 strike-slip earthquakes, recording whether ruptures propagated past the feature. We find that step-overs and bends can arrest rupture and develop a statistical model for passing probability as a function of geometry for each group. Step-overs wider than 1.2 km, single bends larger than 32°, and double bends larger than 38° are breached by rupture half of the time. ~20% of the ruptures terminate on straight segments. We examine how the distribution of earthquake gates influences surface rupture length, inferring an exponential relationship between rupture length and event probability for a given fault. Our findings support that earthquake gates limit the size of large events and help discriminate between different proposed models of rupture propagation.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-403033

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