Re-examination of histrical tsunamis and tsunami risk assessment in Shikoku islnad

源自南开海槽的巨大海啸自古以来就袭击着面向太平洋的四国岛海岸。目前还无法预测下一次南开海啸何时发生、震源在哪里、震级有多大。本文通过在四国岛的野外观测，重新考察了历史上历次海啸（1605年的庆町海啸、1707年的会惠海啸、1854年的安塞-南开海啸和1946年的昭和南开海啸）的海啸淹没高度的空间分布特征。在大范围人为改变海啸波源位置和大小的情况下，利用淹没高度和海啸到达时间的数值估算了四国沿海地区的海啸风险。

The huge tsunamis originated along the Nankai Trough have been attacked the coast of Shikoku island facing to the Pacific Ocean from ancient times. It is impossible to predict when the next Nankai tsunami will occur, where the origin of tsunami wave will be and how big the tsunami will have in its magnitude.In this study, the spacial distribution characteristics of tsunami Inundation height of the histrical tsunamis (the 1605 Keicho, the 1707 Hoei, the 1854 Ansei-Nankai and the 1946 Showa Nankai Tsunami) were re-examined from the field observation in the Shikoku island.Furthermore, the tsunami risks in the coastal region of Shikoku were estimated from the numerical values of the inundation height, the tsunami arrival time, when the location and the size of the tsunami wave origin were artificially varyed in a wide range.