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Tonankai和南开地震的强地面运动模式，我们首先对日本最近发生的破坏性地震(如2004年的Kii-hanto-oki地震(Mw7.3)和2004年的新泻-Ken Chuetsu地震(Mw6.8))进行了强地面运动的计算机模拟，并将模拟结果与密集台阵观测结果进行了比较，通过与观测结果的对比，证实了模拟模型的准确性。因此，该模型适用于南开海槽等未来地震情景的强地面运动预报。历史文献表明，8级地震在这些俯冲带上反复发生，间隔相对均匀，间隔约100年，这表明下一轮8级地震应该在30-40年内发生。模拟结果表明，震源区强度较大，人口中心地震动大而长，优势周期相对较长，大阪和名古屋约为3~6s，东京约为6~10s。这种长周期运动对超高层建筑、长桥和大型储油罐等近期人造建筑的破坏最大。使用细节地下结构模型和高性能计算机，如地球模拟器超级计算机，使在区域尺度上进行高频地震波传播的逼真模拟成为可能。这种高分辨率和高性能的系统使得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成为可能。

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.