SCEC2021 Poster #147: Propagation of Slow Slip Events on a Rough Fault

Poster #147, Fault and Rupture Mechanics (FARM)

Propagation of Slow Slip Events on a Rough Fault

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Poster Presentation

2021 SCEC Annual Meeting, Poster #147, SCEC Contribution #11430 VIEW PDF

Recent studies showed that slow slip events (SSEs) in subduction zones can happen at all temporal and spatial scales and propagate at a wide range of velocities. Heterogeneity of fault properties, such as fault roughness, is often invoked to explain this complex behavior, but how roughness affects SSEs is not well understood. Here we use linear elastic fracture models and quasi-dynamic seismic cycle simulations to model slow slip events on a rough fault. Roughness induces heterogeneity in normal stress and causes locked asperities where normal stress is high. We find that SSEs tend to rupture like a pulse rather than a crack when the amplitude of the normal stress perturbation is large and t...he minimum wavelength is in an appropriate range. In our models, pulse-like ruptures are usually clusters of small subevents and propagate slowly, while crack-like ones are single extensive events and propagate much faster. On a rough fault with a fractal elevation profile, the transition from pulse to crack can also lead to faster back propagation of SSEs. By treating asperities as spring-sliders rupturing in sequence, we explain the difference in forward and backward propagation velocity. Our study provides a possible mechanism for the complex evolution of SSEs from geophysical observations.
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