9:45 AM - 10:00 AM
[STT43-04] Evaluation of long-period ground motions from megathrust earthquakes in the Japan subduction zones using the supercomputer Fugaku
Keywords:Long-period ground motion, 3-D Finite element method, megathrust earthquakes in subduction zones, Seismic-source uncertainties
There are concerns that long-period ground motions will be generated by megathrust earthquakes in subduction zones. And long-period ground motions may have a significant impact on buildings with long natural period, such as tall buildings and seismically isolated buildings. On the other hand, it is not economical to design buildings to sustain only minor damage from the maximum ground motions caused by megathrust earthquakes, which has a low probability of occurrence. It is desirable to design the building with appropriate consideration of the variation in seismic intensity and the degree of building damage. Therefore, it is important to understand the seismic intensity and variation of long-period seismic motions caused by megathrust earthquakes. In this paper, we evaluated the long-period ground motions caused by the megathrust earthquakes in the Japan subduction zones by using the 3D-FEM with the seismic-source models considering the uncertainty of the seismic-source characteristics.
The seismic motions were evaluated using the large-scale 3D-FEM calculation program "E-wave FEM" on the supercomputer "Fugaku". The subsurface structure is based on the shallow and deep layers combined model of the National Research Institute for Earth Science and Disaster Resilience (NIED) and the plate structure is based on the Japan Integrated Velocity Structure Model of the Headquarters for Earthquake Research Promotion (HERP). The model was divided into tetrahedral quadratic elements with a period of more than 3.3 seconds and a size that maintains at least five elements per wavelength. The Earth Simulator was used for mesh dividing. We set up seismic-source models considering the uncertainty of seismic-source characteristics in asperity sizes, locations, and rupture initiation point locations based on the models of the Cabinet Office and Kawabe et al. (2013). The other seismic-source characteristics were in accordance with the Recipe for Predicting Strong Ground Motions of the HERP.
We calculated the long-period ground motions using the above analysis method, subsurface model, and seismic-source models. The intensity of long-period ground motions was strongly affected by the subsurface structure. We will report the effect of seismic-source characteristics on the spatial distribution of the seismic intensity.
Acknowledgements : This work was supported by MEXT as “Program for Promoting Researches on the Supercomputer Fugaku” (Large-scale numerical simulation of earthquake generation, wave propagation and soil amplification, JPMXP1020200203) and used computational resources of the supercomputer Fugaku provided by the RIKEN Center for Computational Science (Project ID: hp220171). The calculation code was developed by the Earthquake Research Institute of the University of Tokyo and modified by JAMSTEC. This work was also used the Earth Simulator provided by JAMSTEC. We used strong-motion records from K-NET and KiK-net of the NIED, the shallow and deep layers combined model of the NIED and the Japan Integrated Velocity Structure Model of the HERP.
The seismic motions were evaluated using the large-scale 3D-FEM calculation program "E-wave FEM" on the supercomputer "Fugaku". The subsurface structure is based on the shallow and deep layers combined model of the National Research Institute for Earth Science and Disaster Resilience (NIED) and the plate structure is based on the Japan Integrated Velocity Structure Model of the Headquarters for Earthquake Research Promotion (HERP). The model was divided into tetrahedral quadratic elements with a period of more than 3.3 seconds and a size that maintains at least five elements per wavelength. The Earth Simulator was used for mesh dividing. We set up seismic-source models considering the uncertainty of seismic-source characteristics in asperity sizes, locations, and rupture initiation point locations based on the models of the Cabinet Office and Kawabe et al. (2013). The other seismic-source characteristics were in accordance with the Recipe for Predicting Strong Ground Motions of the HERP.
We calculated the long-period ground motions using the above analysis method, subsurface model, and seismic-source models. The intensity of long-period ground motions was strongly affected by the subsurface structure. We will report the effect of seismic-source characteristics on the spatial distribution of the seismic intensity.
Acknowledgements : This work was supported by MEXT as “Program for Promoting Researches on the Supercomputer Fugaku” (Large-scale numerical simulation of earthquake generation, wave propagation and soil amplification, JPMXP1020200203) and used computational resources of the supercomputer Fugaku provided by the RIKEN Center for Computational Science (Project ID: hp220171). The calculation code was developed by the Earthquake Research Institute of the University of Tokyo and modified by JAMSTEC. This work was also used the Earth Simulator provided by JAMSTEC. We used strong-motion records from K-NET and KiK-net of the NIED, the shallow and deep layers combined model of the NIED and the Japan Integrated Velocity Structure Model of the HERP.