Finite Difference Simulations of Seismic Wave Propagation for the 2007 Mw 6.6 Niigata-ken Chuetsu-Oki Earthquake: Validity of Models and Reliable Input Ground Motion in the Near-Field

Aochi, Hideo; Ducellier, Ariane; Dupros, Fabrice; Delatre, Mickaël; Ulrich, Thomas; Martin, Florent De; Yoshimi, Masayuki

doi:10.1007/s00024-011-0429-5

Cited by 19 publications

(19 citation statements)

References 29 publications

(21 reference statements)

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“…We tested two very different earthquake scenarios in Ondes3D. The first one is the Mw 6.6 Niigata Chuetsu‐Oki (2007) from Japan . Running the full simulation (6000 time steps) takes an unreasonable amount of time, especially because several executions are needed to obtain statistically significant results.…”

Section: Results and Evaluationmentioning

confidence: 99%

“…The first one is the Mw 6.6 Niigata Chuetsu-Oki (2007) from Japan. 19 Running the full simulation (6000 time steps) takes an unreasonable amount of time, especially because several executions are needed to obtain statistically significant results. So, in order to keep a reasonable duration for the experiments, we limited this simulation to the first 500 time steps.…”

Section: Testbed Validation Methodology and Ondes3d Workloadmentioning

confidence: 99%

“…It has two AMD Opteron 6344 processors per node, using an Infiniband 40G network (MT27500 Family). We simulated the first 500 time steps of the Mw 6.6 2007 Niigata Chuetsu‐Oki earthquake, using a grid of dimensions 1152 × 1152 × 384, adjusted to the increased computational power of this cluster. We evaluate four load balancing heuristics (RefineLB, HwTopoLB, and HierarchicalLB) with two over‐decomposition levels (8 and 16), and an MPI_Migrate call every 20 time steps.…”

Section: Adaptive Mpi: Load Balancing With Over‐decompositionmentioning

confidence: 99%

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Performance modeling of a geophysics application to accelerate over‐decomposition parameter tuning through simulation

Tesser

Schnorr

Legrand

et al. 2018

Concurrency and Computation

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Summary Finite‐difference methods are commonplace in High Performance Computing applications. Despite their apparent regularity, they often exhibit load imbalance that damages their efficiency. We characterize the spatial and temporal load imbalance of Ondes3D, a typical finite‐differences application dedicated to earthquake modeling. Our analysis reveals imbalance originating from the structure of the input data, and from low‐level CPU optimizations. Ondes3D was successfully ported to AMPI/CHARM++ using over‐decomposition and MPI process migration techniques to dynamically rebalance the load. However, this approach requires careful selection of the over‐decomposition level, the load balancing algorithm, and its activation frequency. These choices are usually tied to application structure and platform characteristics. In this article, we propose a workflow that leverages the capabilities of SimGrid to conduct such study at low experimental cost. We rely on a combination of emulation, simulation, and application modeling that requires minimal code modification and manages to capture both spatial and temporal load imbalance to faithfully predict the performance of dynamic load balancing. We evaluate the quality of our simulation by comparing simulation results with the outcome of real executions and demonstrate how this approach can be used to quickly find the optimal load balancing configuration for a given application/hardware configuration.

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Section: Results and Evaluationmentioning

confidence: 99%

Section: Testbed Validation Methodology and Ondes3d Workloadmentioning

confidence: 99%

Section: Adaptive Mpi: Load Balancing With Over‐decompositionmentioning

confidence: 99%

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Performance modeling of a geophysics application to accelerate over‐decomposition parameter tuning through simulation

Tesser

Schnorr

Legrand

et al. 2018

Concurrency and Computation

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“…• the 1-D layered geological model proposed by Aochi et al [27], representative for the propagation of the long-period (LP) ground motion (i.e. 0.1-3.75 Hz) at a regional scale (see the velocity and attenuation properties listed in Table 1);…”

Section: Construction Of the Regional Scale Scenariomentioning

confidence: 99%

“…an area of approximately 68 km ×50 km ×50 km). Further details Table 1: Properties of the Aochi2013 profile [27]. z represents the depth of the upper layer surface, V P and V S are the P-wave and S-wave velocities respectively, Q P and Q S the quality factors for P-wave and S-wave respectively.…”

Section: Construction Of the Regional Scale Scenariomentioning

confidence: 99%

Broad-band 3-D earthquake simulation at nuclear site by an all-embracing source-to-structure approach

Gatti

Touhami

López-Caballero

et al. 2018

Soil Dynamics and Earthquake Engineering

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The scope of this paper is to give an insight into the advantages of a new, allembracing, modeling approach of a strong ground motion scenario, by carrying out a source-to-structure analysis at regional scale, accounting explicitly for the uncertainties related to the databases and the models. To this end, a suitable case-study is represented by the 2007 Mw6.6 Niigata-Ken Chūetsu-Oki seismic sequence (west Japan), that damaged the Kashiwazaki Kariwa Nuclear Power Plant. This study describes the effect of the wave propagation path within the Earth's crust on the seismic response of nuclear reactor buildings located nearby a seismogenic source. The multiscale problem is de-coupled into three steps: (1) a parallel simulation of seismic-wave propagation throughout the Earth's crust at regional scale (≈ 60 km wide, major 3-D geological interfaces found below the nuclear site), reliable up to 5.0 Hz; (2) a mid hybridization step consisting in enriching the synthetic wave-field at high frequency (up to 30 Hz), employing an Artificial Neural Network to predict the short-period (SP) spectral ordinates; (3) a high-resolution structural dynamic analysis, introducing the hybrid broadband synthetics as input wave-motion. A simplified stress-test is performed, ✩ Fully documented templates are available in the elsarticle package on CTAN.

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Using Simulation to Evaluate and Tune the Performance of Dynamic Load Balancing of an Over-Decomposed Geophysics Application

Tesser

Schnorr

Legrand

et al. 2017

Lecture Notes in Computer Science

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Finite difference methods are, in general, well suited to execution on parallel machines and are thus commonplace in High Performance Computing. Yet, despite their apparent regularity, they often exhibit load imbalance that damages their efficiency. In this article, we first characterize the spatial and temporal load imbalance of Ondes3D, a seismic wave propagation simulator used to conduct regional scale risk assessment. Our analysis reveals that this imbalance originates from the structure of the input data and from low-level CPU optimizations. Such dynamic imbalance should, therefore, be quite common and can not be solved by any static approach or classical code reorganization. An effective solution for such scenarios, incurring minimal code modification, is to use AMPI/CHARM++. By over-decomposing the application, the CHARM++ runtime can dynamically rebalance the load by migrating data and computation at the granularity of an MPI rank. We show that this approach is effective to balance the spatial/temporal dynamic load of the application, thus drastically reducing its execution time. However, this approach requires a careful selection of the load balancing algorithm, its activation frequency, and of the over-decomposition level. These choices are, unfortunately, quite dependent on application structure and platform characteristics. (i.e., number of processors and their speed; network topology, bandwidth, latency). Therefore, we propose a methodology that leverages the capabilities of the SimGrid simulation framework and allows to conduct such study at low experimental cost. Our approach relies on a combination of emulation, simulation, and application modeling that requires minimal code modification and yet manages to capture both spatial and temporal load imbalance and to faithfully predict the performance of dynamic load balancing. We evaluate the quality of our simulation by systematically comparing simulation results with the outcome of real executions and demonstrate how this approach can be used to quickly find the optimal load balancing configuration for a given application/hardware configuration.

show abstract

Finite Difference Simulations of Seismic Wave Propagation for the 2007 Mw 6.6 Niigata-ken Chuetsu-Oki Earthquake: Validity of Models and Reliable Input Ground Motion in the Near-Field

Cited by 19 publications

References 29 publications

Performance modeling of a geophysics application to accelerate over‐decomposition parameter tuning through simulation

Performance modeling of a geophysics application to accelerate over‐decomposition parameter tuning through simulation

Broad-band 3-D earthquake simulation at nuclear site by an all-embracing source-to-structure approach

Using Simulation to Evaluate and Tune the Performance of Dynamic Load Balancing of an Over-Decomposed Geophysics Application

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