OpenSWPC: an open-source integrated parallel simulation code for modeling seismic wave propagation in 3D heterogeneous viscoelastic media

Abstract

We have developed an open-source software package, Open-source Seismic Wave Propagation Code (OpenSWPC), for parallel numerical simulations of seismic wave propagation in 3D and 2D (P-SV and SH) viscoelastic media based on the finite difference method in local-to-regional scales. This code is equipped with a frequency-independent attenuation model based on the generalized Zener body and an efficient perfectly matched layer for absorbing boundary condition. A hybrid-style programming using OpenMP and the Message Passing Interface (MPI) is adopted for efficient parallel computation. OpenSWPC has wide applicability for seismological studies and great portability to allowing excellent performance from PC clusters to supercomputers. Without modifying the code, users can conduct seismic wave propagation simulations using their own velocity structure models and the necessary source representations by specifying them in an input parameter file. The code has various modes for different types of velocity structure model input and different source representations such as single force, moment tensor and plane-wave incidence, which can easily be selected via the input parameters. Widely used binary data formats, the Network Common Data Form (NetCDF) and the Seismic Analysis Code (SAC) are adopted for the input of the heterogeneous structure model and the outputs of the simulation results, so users can easily handle the input/output datasets. All codes are written in Fortran 2003 and are available with detailed documents in a public repository.

Comprehensive Detection of Very Low Frequency Earthquakes Off the Hokkaido and Tohoku Pacific Coasts, Northeastern Japan

“…The fault mechanisms were assumed to be consistent with the plate boundary geometry (along the Japan Trench: Nakajima & Hasegawa, 2006;Nakajima et al, 2009; along the Kuril Trench: Kita et al, 2010) and plate motion (NUVEL-1A; DeMets et al, 1994). The source time function was the Küpper's wavelet of a single cycle (Maeda et al, 2017) with a duration of 1 s. Mw of each template was set at 3.8. To contain two signal cycles within a distance range of~100 km, the time window of each template was defined as 150 s from the event origin time.…”

“…We used generic mapping tools to prepare the figures (Wessel et al, ). We used OpenSWPC code (Maeda et al, ; https://github.com/takuto-maeda/OpenSWPC) for numerical simulations, which were performed on the EIC computer system of the Earthquake Research Institute, the University of Tokyo. We used F‐net broadband seismograms (http://www.fnet.bosai.go.jp), National Research Institute for Earth and Disaster Resilience ().…”

Centroid Moment Tensor Inversion of Shallow Very Low Frequency Earthquakes Off the Kii Peninsula, Japan, Using a Three‐Dimensional Velocity Structure Model

“…Seismic sources of five basis moment tensors except for an isotropic one (Kikuchi & Kanamori, 1991) were assumed at each source grid, which was assumed to project onto the PHS boundary at a horizontal interval of 0.1°(blue circles in Figure 1 and yellow stars in Figure 2a) and covered the epicenter region of SVLFEs determined using DONET records (Nakano et al, 2016). A cosine-type moment rate function with a duration of τ s (see Figure 4d of Maeda et al, 2017) was employed. After FDM simulations, moment rate functions with τ = 10-50 s were convolved to make Green's functions with various source durations.…”

Migrations and Clusters of Shallow Very Low Frequency Earthquakes in the Regions Surrounding Shear Stress Accumulation Peaks Along the Nankai Trough

“…Parallel simulation codes (e.g., Gokhberg & Fichtner, ; Maeda et al, ) and realistic 3‐D subsurface structure models (e.g., Eberhart‐Phillips & Bannister, ; Hayes et al, ; Koketsu et al, ) are often utilized to evaluate the effects of subsurface heterogeneities on seismic wave propagation. Takemura et al (, ) conducted numerical simulations of seismic wave propagation to obtain a set of Green's functions using a 3‐D heterogeneous model.…”