2:30 PM - 2:45 PM
[STT39-04] Influence of surface topography modeling on the results of earthquake ground motion evaluation by FEM analysis
Keywords:Long-period ground motion, 3-D Finite element method, Megathrust earthquakes in subduction zone, surface topography
The long-period ground motions caused by megathrust earthquakes in subduction zones that are expected to occur in the future may have a significant impact on buildings with long natural periods, such as high-rise buildings and seismically isolated buildings. In order to take effective countermeasures against such earthquakes, it is important to evaluate the earthquake ground motions from an engineering point of view.
With the recent remarkable improvement in supercomputer performance, large-scale finite element models are increasingly being constructed to evaluate ground motions. Finite element analysis can model ground irregularities in three dimensions. On the other hand, some reports have pointed out the possibility of differences in evaluation results due to differences in modeling methods of ground surface topography. In this study, finite element models are created for the following three methods of modeling the surface topography, and their effects on the results of earthquake ground motion evaluation are analyzed.
(1) Modeling the land and sea topography.
(2) Modeling the land topography and moving the subsurface structures so that the sea topography is flat.
(3) Moving the subsurface structures so that both the land and sea topography are flat.
The seismic ground 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 greater than 3.3 seconds and a size of five elements per wavelength. The Earth Simulator was used to partition the elements.
We calculated the long-period ground motions caused by megathrust earthquakes in the subduction zone using the above analysis method and the subsurface model. We report on the effect of topography on the spatial distribution of the response spectra.
Acknowledgements : This work was supported by MEXT as “Program for Promoting Researches on the Supercomputer Fugaku” (Large-scale numerical simulation of earthquakes by Fugaku supercomputer, JPMXP1020230213) and by JAMSTEC as “Earth Simulator Proposed Research Projects” (Study for engineering application of long-period ground motion evaluation using E-wave FEM).
This work used the computational resources of the supercomputer Fugaku provided by the RIKEN Center for Computational Science and the Earth Simulator provided by the Japan Agency for Marine-Earth Science and Technology. The results of this work were obtained from the code developed by the Earthquake Research Institute, the University of Tokyo, provided by the Fugaku project and modified and operated by JAMSTEC.We used the Japan Integrated Velocity Structure Model of the HERP and the Deep Subsurface Structure Model of the NIED.
With the recent remarkable improvement in supercomputer performance, large-scale finite element models are increasingly being constructed to evaluate ground motions. Finite element analysis can model ground irregularities in three dimensions. On the other hand, some reports have pointed out the possibility of differences in evaluation results due to differences in modeling methods of ground surface topography. In this study, finite element models are created for the following three methods of modeling the surface topography, and their effects on the results of earthquake ground motion evaluation are analyzed.
(1) Modeling the land and sea topography.
(2) Modeling the land topography and moving the subsurface structures so that the sea topography is flat.
(3) Moving the subsurface structures so that both the land and sea topography are flat.
The seismic ground 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 greater than 3.3 seconds and a size of five elements per wavelength. The Earth Simulator was used to partition the elements.
We calculated the long-period ground motions caused by megathrust earthquakes in the subduction zone using the above analysis method and the subsurface model. We report on the effect of topography on the spatial distribution of the response spectra.
Acknowledgements : This work was supported by MEXT as “Program for Promoting Researches on the Supercomputer Fugaku” (Large-scale numerical simulation of earthquakes by Fugaku supercomputer, JPMXP1020230213) and by JAMSTEC as “Earth Simulator Proposed Research Projects” (Study for engineering application of long-period ground motion evaluation using E-wave FEM).
This work used the computational resources of the supercomputer Fugaku provided by the RIKEN Center for Computational Science and the Earth Simulator provided by the Japan Agency for Marine-Earth Science and Technology. The results of this work were obtained from the code developed by the Earthquake Research Institute, the University of Tokyo, provided by the Fugaku project and modified and operated by JAMSTEC.We used the Japan Integrated Velocity Structure Model of the HERP and the Deep Subsurface Structure Model of the NIED.