1. This is the source code and simulation results of Ariyoshi (2022 JGR). Date: June 11th 2022 2. source and model of Ariyoshi (2022 JGR) 3. version: 69cses4 69cses4: source code (*.f, *.mk) Note that the source code is customized to the Earth Simulator of JAMSTEC which needs special libraries for the FFT operations. Methodology is described in Ariyoshi et al. (2012) Ariyoshi, et al.(2012). Migration process of very low-frequency events based on a chain-reaction model and its application to the detection of preseismic slip for megathrust earthquakes. Earth Planets Space, 64(8), 693-702. https://doi.org/10.5047/eps.2010.09.003 4. common: green's function file (*.grn) and input model (simu3dscalar.dat) 5. model: 71s02r110dd200a230b215L199ob : model A 7is02r110dd200a230b100L199ob : model B 7is02r110dd200a230b215L199ob : model C 7ih02r110dd200a230b100L199ob : model D *.ctl : control file *.o?? : input file *.ini : initial condition file *_hg028.dat & *_v_vel.dat : datafile of Figure 5 6. Please use refer Ariyoshi (2022 JGR) if you use this code with any modifications.