STT55-01

Room:103

Time:May 27 14:30-14:45

Advanced Disaster Simulation Researches on Earthquakes and Tsunamis using High Performance Computing System Kei
KANEDA, Yoshiyuki1∗ ; FURUMURA, Takashi2 ; IMAMURA, Fumihiko3 ; HORI, Muneo2
1Disaster mitigation research center, Nagoya University, 2 Earthquake Research Institute, University of Tokyo, 3 International
Research Institute of Disaster Science, Tohoku University‘Kei’ computer is one of the highest computing system in the world. Using ‘Kei’ computer, we are performing the advanced
simulation for disaster mitigation by earthquakes and tsunamis in a project ‘Study for Advancement of Prediction Accuracyon Earthquake and Tsunami’. In this research project, we have three research fields as Earthquake simulation research field,
Tsunami research filed and Damage estimation research field.
In Earthquake simulation research field, we are developing the scenario simulations of earthquake recurrences on the subducting plate around Japan. As other earthquake simulation researches, we are simulating seismic waves based on the scenarios, andthe underground structures using seismographs.
The second research simulation research field on Tsunami hazard, we are developing applications for the simulating tsunami
damages at East Japan earthquake 2011. In this research field, not only damage simulations, but also we are developing the earlytsunami detection system using simulation and real time data. Finally, we will apply it to the Nankai trough seismogenic zone
and etc.
The third research field is the civil engineering research as the adavanced civil engineering structural analyses, seismic response analyses on large scale cities, and agent simulation for more precise and practical evacuations.
Finally, we will integrate these research fields in this project for the seismic simulator on disaster mitigation.
Keywords: high performance computing, disaster mitigation, simulation, earthquake, tsunami

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STT55-02

Room:103

Time:May 27 14:45-15:00

Earthquake Simulations running on K computer
ICHIMURA, Tsuyoshi1∗
1

Earthquake Research Institute,The University of Tokyo

Large-scale high fidelity model can be constructed with recent accumulation of spatial data. Although computational cost ofearthquake simulations using such model is huge, supercomputer (e.g. K computer) is now resolving difficulties and creating
new frontier in this field. In this presentation, recent illustrative examples (crust deformation, earthquake ground motion, soil
amplification, city response etc.) will be shown.
Keywords: Simulation, High performance computing, Computational science

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STT55-03

Room:103

Time:May 27 15:00-15:15

Development of high performance particle simulations of fluid and granular dynamics forcontributing to human society
NISHIURA, Daisuke1∗ ; FURUICHI, Mikito1 ; SAKAGUCHI, Hide1
1

JAMSTEC

Large-scale parallel computing is important for numerically reproducing actual measurement results and dynamics of phenomena in various science and engineering areas, such as civil engineering, bioengineering, and earth sciences. The computational
performance of parallelized software tools plays a critical role in such simulation studies, as these improve the computational
accuracy relative to the simulation resolution within a limited computation time. Recent massively parallel computer systems
based on shared- and distributed-memory architectures employ various types of arithmetic processors. Current processor designs
are known to exhibit totally different computational performance depending on the numerical algorithms and implementation
methods employed. Currently, parallel computing generally uses either a multi-core CPU, graphics processing unit (GPU), or
many integrated core (MIC) processor. Multi-core CPUs have traditionally been used in high-performance computing, whereas
GPUs were originally designed for computer graphics with many arithmetic cores. The common progress of current processor
designs is the increase in the number of cores using vector operations such as single-instruction?multiple-data (SIMD). In sucha situation, the shared-memory parallelization plays a basic but critical role in dealing with the increasing number of arithmetic
cores in an efficient manner.
Numerical simulation methods used in science and engineering include the finite difference method (FDM), finite element
method (FEM), finite volume method (FVM), boundary element method (BEM), and particle simulation method (PSM). Amongthese, PSM has a benefit of being mesh-free, allowing the computation of large-scale deformations and fractures of a continuum
body without expensive remeshing tasks. As a PSM, smoothed particle hydrodynamics (SPH) is often used for tsunami disaster
simulations because of its robustness in free-surface fluid dynamics. The discrete element method (DEM) is one popular PSM
for granular dynamics in which geometrical size and shape attributes are provided for each particle. In the most conventional
formulation of the DEM, the Voigt model in both the normal and tangential directions is considered at each contact point. In
the tangential direction, Coulomb friction is introduced to determine the maximum tangential force and the slip condition. Inaddition, rolling friction can be considered at the contact points. Therefore, the DEM is attractive to simulate granular materials
such as sand, pebbles, and other grains.
However, PSM programs must be implemented carefully to avoid write-access conflicts under shared-memory parallelization,
especially when calculating a resultant force. In addition, it is important for distributed-memory parallelization to dynamicallybalance the computational load between computational nodes. To address these issues, we have proposed parallel algorithms that
use the action-reaction law and parallelize the interaction summation with a reference table to avoid memory access conflicts.
We have also implemented the algorithm of dynamic load balancing by resizing the domain decomposition region. Our methods
were implemented on various parallel processors such as GPU, MIC processor, multi-core CPU on K computer, and vector processor on Earth simulator. In this presentation, we will talk about these parallel algorithms and applications for contributing tohuman society; Tsunami disaster simulations in consideration of structures?soil?fluid interactions and impact dynamics of ballast
particles in rail track are important topics that require a high performance computing resources.

Keywords: DEM, parallel computing, Tsunami, ballast track, particle, SPH

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STT55-04

Room:103

Time:May 27 15:15-15:30

Efficient Domain Partitioning Method for Dynamic BIEM applicable to Non-planar Faults
ANDO, Ryosuke1∗
1

School of Science, University of Tokyo

The boundary integral equation method (BIEM) is a powerful tool to analyze the earthquake rupture dynamics on non-planarfaults. The non-planar fault analysis requires of the boundary integral equations (BIEs) that they are formulated in the real space
and time domain, while those formulate in the spectral domain are limited to the application of the planar fault geometry. However BIEM in the space-time domain has extremely large numerical costs. Due to such large costs particular for the memory
requirement, efficient use of the memory storage of the integration kernel have not be possible. In this study, we develop a new
method to reduce the calculation time and memory requirement greatly without degrading the accuracy in 3-D. We extend themethod proposed by Ando et al. (2007) in 2-D. This method divide the causality cone appealing in the integration kernel tothe domains related to the wave fronts, the near-field term and the static term. We implement the algorithm on K-computer, anddemonstrate the memory storage of the integration kernel becomes possible on the currently available computational environment
owing to the reduced memory requirement. This contributes the efficiency of the numerical analysis considerably. For example,by using the same 6400 nodes, the analysis of the model consisting of 160 thousands fault elements and 1600 time steps took
about a half year with the original method, however it is reduced to about two hours with the current efficient method. The current
method is also shown to be scalable on distributed memory environment to the scale of these nodes. This method is expected
to break through the emerging limitations of the dynamic earthquake rupture simulations with realistic 3-D geometrical models,
and will contribute to widen the spectrum of the applicational works using the dynamic simulations.
Keywords: Boundary element method, Boundary integral equation method, non-planar faults, rupture dynamics, domain partitioning, high speed computing

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STT55-05

Room:103

Time:May 27 15:30-15:45

Current status and issues of Tsunami simulation by HPC
ARIKAWA, Taro1∗
1

Port and Airport Research Institute

The Great East Japan Earthquake of 2011 has shown that a tsunami disaster is not limited to inundation damage in a specified
region, but destruction over a wide area can cause a severe disaster. Because various structures stand on the land, in order toevaluate damage to these structures, it is necessary to perform highly precise evaluations of three-dimensional fluid motion. But
the calculation cost of high precision three-dimensional fluid analysis is very high. So the goals of this research were to develop
a method of coupling STOC (Tomita et al., 2005) and CADMAS-SURF/3D (Arikawa et al., 2005) to establish a method ofefficiently calculating every stage from wave source to runup, and to verify its applicability.
Summing up shows that in order to improve overall calculation speed, as long as this method is adopted, the calculation domainof STOC-ML is as small as possible and CS3D is as large as possible, and it is important the number of calculation nodes beincreased to the level eliminating synchronicity standby state.
Under this condition, calculation time is about 2s/step, and if the mesh is 1m wide, the time interval is an average of about
0.004s/step, so in order to calculate integration time of 1s, about 500s are necessary.
The coupling simulator with structure analysis is also shown. The breakwater under tsunami overflow was reproduced.
Finally, the issues of the future tsunami simulation will be discussed.
Keywords: Tsunami simulation, High performance computing, Tsunami, Coupling simulation

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STT55-06

Room:103

Time:May 27 15:45-16:00

Two-phase flow simulation in the large digital rock by using high performance cluster
JIANG, Fei1 ; TSUJI, Takeshi1∗
1

I2CNER, Kyushu UniversityA numerical implementation based on a Graphics Processing Unit (GPU) is proposed for the acceleration of the two-phasesimulation using Lattice Boltzmann Method (LBM). The LBM yields regular, data-parallel computations; therefore, it is especially well fitted to GPU calculations. This study focuses on the application of the LBM for fluid displacement computations
in real rock sample. For this purpose, the digital rock model is reconstructed from the micro-CT scanned images of reservoir
sample with a resolution of 2.0 um. In order to obtain reliable and accurate results from the developed numerical model, thecomputational domain must be large enough to cover the representative element size (REV) of sample rock. As a result, porescale LBM simulation of multiphase porous medium systems with sufficient resolution and large grid-number are very computationally challenging. To achieve this extremely large-scale simulation, multi-GPU parallel scheme by using CUDA and MPI
is developed. Careful optimizations include sparse storage scheme, efficient domain decomposition and non-blocking communication are desired for algorithm implementation. Finally, we succeeded to perform a two-phase simulation with 10 billion(1000 x1000x1000) mesh sizes using a small-scale GPU cluster. The developed large-scale simulation method enables the direct
upscaling from pore scale to core scale which is a very powerful tool for many engineering applications such as enhanced oil
recovery (EOR) and Carbon Capture and Storage (CCS).
Keywords: Digital rock, lattice Boltzmann method, two-phase simulation, GPU, CO2 storage

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STT55-P01

Room:Convention Hall

Time:May 27 18:15-19:30

Introduction for Creating future of solid Earth science with HPC
HORI, Takane1∗ ; KANEDA, Yoshiyuki2 ; HORI, Muneo3 ; HINO, Ryota4 ; ARIKAWA, Taro5 ;TODORIKI, Masaru6
1JAMSTEC, 2 Nagoya University, 3 University of Tokyo, 4 Tohoku University, 5 Port and Airport Research Institute, 6 Universityof Tokyo
In this session we will explore the scientific and social issues that can be addressed by Earth scientists over the next 10-20
years using high performance computing (HPC). We will discuss future problems and prospects in the development of solid Earthscience, especially for simulation technology in earthquake and tsunami disaster mitigation, new methods for big data analysesof seismic waves and crustal deformation obtained by high-density observation networks, construction of multi-scale solid Earthmodels, and so on. We welcome both earth scientists working on computational, observational and theoretical aspects of thephysics of the solid Earth, and specialists on disaster mitigation, to discuss the role of HPC in solving future problems in thisfield. We will introduce current states in this talk.

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