Computational Disaster Mitigation and Reduction Research Team (Oishi)

Research summary

Main research results

Hazard map based on large-scale simulations

We have developed a next-generation hazard map depicting a possible scenario resulting from the predicted Nankai Trough Earthquake. Using large-scale numerical simulations, the map includes four cities in Hyogo prefecture.

Previously, hazard maps were made from the results of simpler numerical simulations and empirical equations based on distribution of ground motion index values. However, the latest simulations using the K computer for next-generation hazard maps have simulated propagation and amplification of seismic waves, and then calculated their physical impact on buildings. In other words, the latest simulations have explicitly calculated the fragility curve. This calculation is an essential component for estimating damage to cities caused by earthquakes because the simulation includes the elemental physical process of the propagation of waves and the response of buildings to these waves. We are applying it to the other disasters like floods, landslides and mud slides; and we will estimate the propagation of the disaster impact into traffic and economy.

Our numerical simulation developed to create next-generation hazard maps has two advanced features. The first is the comprehensive simulation of an entire city 100km2 in area. Comprehensive simulation means both geotechnical wave propagation and urban structures to be simulated simultaneously. This large-scale comprehensive calculation has been performed on the K computer.Consequently, this research achievement in the computational science had been chosen as a finalist for the Gordon Bell Prize. It is much more expected with Fugaku in the near future. The second feature enables the technology to represent existing buildings in numerical simulations as data and equations. By using newly developed data processing platform, hundreds of thousands of buildings can be represented in such simulations.

Numerical city structure model

Representative papers

• O-tani, H., Hori, M., Wijerathne, L.:
  “Automated Model Construction for Seismic Disaster Assessment of Pipeline Network in Wide Urban Area”
  Earthquakes, Intech, (2018).
  
• Hori, M., Ichimura, T., Wijerathne, L., Ohtani, H., Chen, J., Fujita, K., Motoyama, H.:
  “Application of High Performance Computing to Earthquake Hazard and Disaster Estimation in Urban Area”
  Front. Built Environ., (2018).
  
• Fujita, K., Horikoshi, M., Ichimura, T., Meadows, L., Nakajima, K., Hori, M., Maddegedara, L.:
  “Development of Element-by-Element Kernel Algorithms in Unstructured Implicit Low-Order Finite-Element Earthquake Simulation for Many-Core Wide-SIMD CPUs.”
  Computational Science - ICCS 2019, Lecture Notes in Computer Science, vol 11536, (2019).
  
• Maddegedara, L., Gill, A., Poledna, S., Hori, M., Inoue H., Noda T., Toda K., and Ichimura T.:
  “Distributed Memory Parallel Implementation of Agent Based Economic Models”
  Lecture Notes in Computer Science, (2019).
  
• Chen J., Takeyama, T., O-tani, Fujita, K., Motoyama, H., Hori, M.:
  “Using High Performance Computing for Liquefaction Hazard Assessment with Statistical Soil Models”
  International Journal of Computational Methods, Vol. 16, p.1840005(1-21), (2019), (https://doi.org/10.1142/S0219876218400054).
  
• Chen J., O-tani, H., Takeyama, T., Oishi, S., Hori, M.:
  “Toward a numerical-simulation-based liquefaction hazard assessment for urban regions using high-performance computing”
  Engineering Geology, Vol.258, (2019), (https://doi.org/10.1016/j.enggeo.2019.105153).
  
• Chen J., Takeyama, T., O-tani, H., Yamanoi, K., Oishi, S., Hori, M.:
  “Code verification of soil dynamics simulations: A case study using the method of numerically manufactured solutions”
  Computers and Geotechnics, Vol.117, (2019), (https://doi.org/10.1016/j.compgeo.2019.103258).
  
• Yamanoi, K., Oishi, S., Kawaike, K., Nakagawa, H.:
  “Predictive Simulation of Concurrent Debris Flow: How Slope Failure Locations Affect Predicted Damage”
  Journal of Flood Risk Management, (2021).
  
• Takeyama, T., O-tani, H., Oishi, S., Hori, M., Iizuka, A.:
  “Automatic construction of three-dimensional ground model by data processing”
  in IEEE/ASME Transactions on Mechatronics, vol.26, no.6, 2881-2887, (2021).
  
• Yokoya, N., Yamanoi K., He, W., Baier, G., Adriano, B., Miura, H., Oishi, S.:
  “Breaking the Limits of Remote Sensing by Simulation and Deep Learning for Flood and Debris Flow Mapping”
  in IEEE Transactions on Geoscience and Remote Sensing, vol.60, pp. 1-15, (2022).
  

Annual Reports