虎扑电竞 虎扑电竞

Makes tsunami warnings more precise and helps cities become more resilient to damage

International 虎扑电竞 Institute of Disaster Science (IRIDeS), Tohoku University and Fujitsu Laboratories Ltd. today announced their joint development of a high-resolution tsunami model, able to run on a supercomputer, and based on Tohoku University's existing TUNAMI-N2 (*1) simulation model, which is in widespread use internationally. For this project, IRIDeS prepared the model to perform high-resolution calculations, and Fujitsu Laboratories implemented methods for high-efficiency parallelization.

The Great East Japan Earthquake far exceeded the scale of previously envisioned earthquakes, causing underestimations of tsunami height made three minutes after the start of the earthquake, exposing an urgent need to improve methods of real-time estimation. The disaster also illustrated the need for information beyond wave height, such as the scope of flooding. Now Tohoku University and Fujitsu Laboratories have developed a tsunami model that quickly predicts the extent of flooding from sea surface deformation, which is the source of the tsunami and is estimated based on observation data on the shape of the tsunami out at sea and on tectonic shifts onshore at the time of the earthquake. For example, flooding in the Great East Japan Earthquake started in Sendai one hour after the earthquake struck. With this technology basic predictions of where flooding would occur in the City of Sendai can be provided in about 10 minutes for the Great East Japan Earthquake case.

By making high-resolution, real-time predictions of general tsunami-flooding conditions, Tohoku University and Fujitsu Laboratories will contribute to more effective disaster-response measures.

This research was published on February 24^th in an online preview of Geophysical 虎扑电竞 Letters, a journal of the American Geophysical Union.

Background

In the aftermath of the Great East Japan Earthquake, for the purpose of improving tsunami disaster prevention, work has proceeded on laying out an extensive, fine-grained offshore tsunami observation grid. At the same time, to make the best possible use of that observation data, there has also been a vigorous R&D push to develop analytical techniques for more sophisticated real-time tsunami forecasting.

Issues

Tohoku University and Fujitsu Laboratories have moved forward on joint research since 2014 to enable not only predictions for when tsunamis will hit coastlines and for tsunami wave heights, which are released by the Japan Meteorological 虎扑电竞ncy, but also real-time forecasts of the extent of tsunami-induced flooding, which are important for disaster-response measures. Tsunami flood simulations currently in wide use are an important practical tool for disaster preparedness, producing flood-hazard maps and more. But this simulator is computationally intensive, and takes time to solve nonlinear equations. As a result, it typically has not been used for real-time analysis.

About the 虎扑电竞

Under the research project "The advancement of the accuracy of tsunami prediction" (principal investigator: Fumihiko Imamura; project number: hp140222), which is a project of the HPCI Strategic Program for Innovation 虎扑电竞 Field 3, "Advanced Prediction 虎扑电竞es for Natural Disaster Prevention and Reduction," (*2) advanced by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Fujitsu Laboratories and Tohoku University have investigated the feasibility of using their parallelized tsunami model for real-time flood analysis, making full use of the computational power of the K computer (*3) to perform highly efficient parallel computations.

Using a wave-source model estimated from observation data collected from the tsunami caused by the Great East Japan Earthquake, the team conducted flood simulations to verify the technology. To reproduce the tsunami's flood dynamics in detail, the team used high-resolution topographic data, modeling an approximate 10 km area around the City of Sendai's coastal districts with a resolution of 5 m.

Results

This testing showed that simulations of the general extent of flooding in the City of Sendai could be completed in two minutes. Performing the same computations on a workstation would take several days. Even including the time needed to analyze the tsunami wave source from the observation data, the time to provide basic flood predictions was estimated to be approximately 10 minutes. This would have been sufficiently fast for the tsunami caused by the Great East Japan Earthquake, which took one hour to reach the City of Sendai.

In addition, using this high-resolution analysis, the team was able to reproduce results actually seen from the tsunami caused by the Great East Japan Earthquake. For example, the embankment of the Sendai East Road was able to stop the tsunami, which then passed through passageways underneath it. For example, Figure 1 shows the estimated arrival times of the tsunami. Figure 2 displays the probability of buildings in a particular area being destroyed based on statistical information. These predictions are given by the newly developed tsunami model.

Figure 1: Predicted tsunami arrival times	Figure 2: Predicted probability of building destruction

Future Plans

Tohoku University and Fujitsu Laboratories will apply this technology to hypothetical cases of a massive earthquake in the Nankai Trough, which is a large region from which earthquakes originate, and test its effectiveness. In doing so, it is hoped that precise and targeted tsunami forecasts will help local governments and businesses around seaports better prepare tsunami-response measures.

Glossary and Notes

1. TUNAMI-N2

A tsunami model used in Tsunami Inundation Modeling Exchange (TIME), an international project carried out by Tohoku University in collaboration with UNESCO and the International Union of Geodesy and Geophysics since 1991. TUNAMI is the name for "Tohoku University Numerical Analysis Model for Inundation," with N2 referring to flood analysis.

2. HPCI Strategic Program for Innovation 虎扑电竞 Field 3, "Advanced Prediction 虎扑电竞es for Natural Disaster Prevention and Reduction"

A project led by the Japan 虎扑电竞ncy for Marine-Earth Science and Technology with the strategic objective to "globally project tropical cyclone trends in simulated global warming, demonstrate prediction of local heavy rain falls, establish the foundation for next-generation earthquake hazard maps and improve tsunami warning accuracy."

3. K computer

A supercomputer developed jointly by RIKEN and Fujitsu Limited, installed at RIKEN's Advanced Institute for Computational Science.

About Fujitsu

Fujitsu is the leading Japanese information and communication technology (ICT) company offering a full range of technology products, solutions and services. Approximately 162,000 Fujitsu people support customers in more than 100 countries. We use our experience and the power of ICT to shape the future of society with our customers. Fujitsu Limited (TSE: 6702) reported consolidated revenues of 4.8 trillion yen (US$46 billion) for the fiscal year ended March 31, 2014. For more information, please see: http://www.fujitsu.com.

About Fujitsu Laboratories

Founded in 1968 as a wholly owned subsidiary of Fujitsu Limited, Fujitsu Laboratories Ltd. is one of the premier research centers in the world. With a global network of laboratories in Japan, China, the United States and Europe, the organization conducts a wide range of basic and applied research in the areas of Next-generation Services, Computer Servers, Networks, Electronic Devices and Advanced Materials. For more information, please see: http://jp.fujitsu.com/labs/en.
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