Evolving Seismic and Aseismic Slip on a Heterogeneous Frictional Fault with Heat Generation and Temperature-Dependent Creep

Session: Earthquake Source Parameters: Theory, Observations and Interpretations [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

We study the evolution of seismicity and seismic/aseismic slip partitioning on a fault using a generalized version of the Ben-Zion and Rice (1993) model for a discrete cellular fault in elastic halfspace. Previous versions of the model were shown to produce a wide variety of realistic results (e.g., frequency-size statistics, hypocenter distributions, slip distributions, and temporal occurrence) using distributions of static and kinetic friction levels and creep properties that vary in space but are fixed in time. In the present study we incroporate heat generation due to slip within a 1 cm wide zone, subsequent diffusion cooling to the halfspace, and related changes of temperature-dependent creep on the fault. We assume a power law dependency of creep on the local shear stress, with temperature-dependent parameters based on the Arrhenius equation. Temperature rises due to seismic slip lead to increased aseismic slip, which can lead to further heat generation and stress concentrations in a feedback loop. The partitioning of seismic/aseismic slip and the temporal distribution of seismicity are strongly affected by the activation energy in the Arrhenius equation, and frictional parameters that control the local stress drop after failure. The current results can be summarized as follows: (1) The feedback between heat generation and creep produces space-time evolution of seismic coupling, (2) A constant or increasing activation energy with depth lead to clear overall depth separation of brittle and creeping fault sections, (3) A heterogeneous distribution of activation energies can produce variations in the temporal distribution of seismicity, which are strongest when the fault has alternating regions of higher and lower activation energies and (4) A realistic aftershock sequence can be generated by combining the temperature dependent creep and cooling.

Presenting Author: Bruce Zhou

Authors