Integrating Earthquake Cycles, Plate Tectonics and Mantle Dynamics Using Scalable GPU-accelerated Pseudo-transient Simulations

Earthquakes are often treated as isolated ruptures in simplified media. Growing geodetic, seismological, and geological datasets reveal deformation that extend far beyond individual events and reflect interactions between fault slip, plate motion, and mantle dynamics. Our objective is to adapt a High-Performance-Computing geodynamic code base to resolve earthquake rupture, plate tectonics forces, and mantle dynamics consistently across time scales withing a single modeling framework. Our new framework QuakeSystem.jl is being built upon an efficient and scalable matrix-free thermo-mechanical pseudo-transient framework JustRelax.jl. This requires updates to an advanced time-stepping algorithm, invariant rate-and-state dependent friction and the use of inertia. This approach allows us to explore system-scale interactions at high spatial resolution in 2D and 3D, including episodic variations in subduction rates, a flexural response of the overriding plate, and transient changes in mantle flow associated with large earthquakes. Matrix-free pseudo-transient code will significantly reduce computational cost and memory requirements while enabling massively parallel simulations on GPU architectures. This will allow us to produce many forward models efficiently, which will be incorporated in and adjoint-based inversion of megathrust slip and bulk rheological parameters from satellite-derived and ground-based deformation data, without requiring separate simulations for each parameter. By integrating observations across pre-, co-, and post-seismic periods, the framework enforces temporal and mechanical consistency and reduces non-uniqueness.