Prediction of strong ground motion pattern for the Nankai and Tonankai earthquake based on high-resokution 3D large scale numerical simulation.

为了评估未来东京和南海地震的强地面运动模式，我们首先对日本最近破坏性地震的强地面运动进行了计算机模拟;比如说纪伊半岛冲地震（MW7.3）2004年，和新泻县中越地震（Mw6.8）的模拟结果，并将模拟结果与密台观测结果进行了比较，验证了模拟模型的准确性。因此，该模型被认为是适合于预测未来的地震场景，如事件在南海海槽的强地面运动。历史文献表明，沿着这些俯冲带沿着反复发生过8级地震，相对均匀的间隔约为100年，这表明下一系列8级地震应在30-40年内发生。模拟结果显示，震源区沿着发展为大强度，人口密集地区地震动大而长，卓越周期较长，大坂和名古屋为3 ~ 6s，东京为6 ~ 10 s。这样的长周期运动对最近的人造建筑物，如高层建筑、长桥和大型储油库的破坏性最大。使用详细的地下结构模型和高性能计算机，如Earth Simulator超级计算机，可以在区域范围内对高频地震波传播进行逼真的模拟。这种高分辨率和高性能的系统使得有可能对过去和未来大地震的地震波传播和强地面运动进行全面研究。

In order to evaluate the pattern of strong ground motions expecting fur future Tonankai and Nankai earthquake, we first conducted computer simulations of strong ground motions associated with recent damaging earthquakes in Japan ; such as the Kii-hanto-oki earthquake(Mw7.3) in 2004, and the Niigata-ken Chuetsu earthquake(Mw6.8) in 2004 and compared the simulation results with dense array observations.Through comparison with observations, the accuracy of the simulation model was confirmed. Thus, the model is considered to be suitable for predicting the strong ground motions for future earthquake scenarios such as events in the Nankai Trough. Historical documentation indicates that M8 earthquakes have occurred repeatedly along these subduction zones, at relatively uniform intervals of about 100 years, suggesting that the next series of M8 earthquakes should occur within 30-40 years. The simulation results warn the development of large intensity along the source region and large and lengthy ground motions in population centers, with relatively longer predominant period about 3 to 6s(Osaka and Nagoya) and 6 to 10s(Tokyo). Such long-period motions would be most damaging for recent, man-made constructions such as very tall buildings, long bridges, and large oil reservation tanks.Using the detail subsurface structural model and high-performance computer, such as the Earth Simulator supercomputer have made it possible to perform realistic simulations of high-frequency seismic wave propagation on a regional scale. Such high-resolution and high-performance systems made it possible to conduct a comprehensive study on seismic wave propagation and strong ground motions for the past and future large earthquakes.