Large-scale earthquake sequence simulations on 3D nonplanar faults using the boundary element method accelerated by lattice H-matrices

TL;DR

This paper introduces a scalable method for large-scale earthquake simulations on complex 3D faults using lattice H-matrices, achieving significant acceleration and enabling unprecedented computational modeling on supercomputers.

Contribution

The study develops a novel earthquake simulation method for 3D nonplanar faults utilizing lattice H-matrices, improving scalability and efficiency over traditional H-matrix approaches.

Findings

Achieved over 10^4 parallel acceleration with 10^5 degrees of freedom.

Demonstrated >10-fold performance improvement over traditional H-matrices.

Verified mesh convergence on complex fault geometries.

Abstract

Large-scale earthquake sequence simulations using the boundary element method (BEM) incur extreme computational costs through multiplying a dense matrix with a slip rate vector. Hierarchical matrices (H-matrices) have often been used to accelerate this multiplication. However, the complexity of the structures of the H-matrices and the communication costs between processors limit their scalability, and they therefore cannot be used efficiently in distributed memory computer systems. Lattice H-matrices have recently been proposed as a tool to improve the parallel scalability of H-matrices. In this study, we developed a method for earthquake sequence simulations applicable to 3D nonplanar faults with lattice H-matrices. We present a simulation example and verify the mesh convergence of our method for a 3D nonplanar thrust fault using rectangular and triangular elements. We also performed performance and scalability analyses of our code. Our simulations, using over 10^5 degrees of freedom, demonstrated a parallel acceleration beyond 10^4 MPI processors and a >10-fold acceleration over the best performance when the normal H-matrices are used. Using this code, we can perform unprecedented large-scale earthquake sequence simulations on geometrically complex faults with supercomputers. The software HBI is made an open-source and freely available.