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Bridging the Gap Between Millions of Years and Milliseconds in Visco-Elasto-Plastic Subduction Earthquake Sequence Models

Description: 

Deformation in subduction zones is characterized by the interaction of multiple deformation processes that occur over a wide range of temporal and spatial scales. Basing earthquake sequence models on continuum mechanics allows simulating a large spectrum of visco-elasto-plastic deformation, including earthquake dynamics, spontaneous fault evolution, lithospheric deformation, mantle flow, and topographic evolution [1]. Such seismo-tectonic models have been unable to resolve coseismic time scales, hence not providing insight into all stages of the seismic cycle. Understanding the interaction between slab, overriding plate, and mantle on sub-year time scales has therefore been difficult. We simulate the coupled mechanical and thermal evolution of a subduction zone with a visco-elasto-plastic rheology. We self-consistently evolve a mature subduction zone with a heterogeneous subduction channel by simulating the subduction of a 2D slab for 4 million years. Adopting an invariant reformulation of rate- and state-dependent friction and an adaptive time stepping scheme [2] enables us to span the gap between millions of years of tectonic evolution and milliseconds of seismic rupture. We resolve all relevant time scales of the seismic cycle in a realistic subduction zone setting. Depending on the characteristic slip distance and the ratio of seismogenic zone width over nucleation size W/h*, we generate slow slip events with slip rates between 10^-8 m/s and 10^-4 m/s and earthquakes with slip rates on the order of m/s. Earthquake nucleation and propagation is fully resolved and leads to the generation of seismic waves. Earthquakes nucleate in the heterogeneous subduction channel near the 350°C isotherm and propagate upwards to arrest at the up-dip velocity-strengthening segment. We will comment on technical challenges, enabling cross-scale modeling of increasingly complex scenarios and its potential.

References

[1] van Dinther et al., JGR, 2013b, doi.org/10.1002/2013JB010380

[2] Herrendörfer et al., JGR, 2018, doi.org/10.1029/2017JB015225

Session: From Geodynamics to Earthquake Rupture, Models That Cross Time- and Length-Scales - I

Type: Oral

Date: 5/3/2024

Presentation Time: 05:00 PM (local time)

Presenting Author: Alexander

Student Presenter: No

Invited Presentation: Yes

Authors