Katsuhiro MASAI
Predicting the Tsunami that have possibility to arrive in the area of Niigata coast
Naoyuki INUKAI
Niigata Prefecture is often damaged by the Tsunami. Construction a breakwater which stop Tsunami on the coast is thought to reduce the damage caused by the Tsunami. It also need to estimate the presence or absence of the Tsunami and magnitude when the earthquake actually occurred. The size, the interval and the probability of occurrence is estimated for more than M7.5 earthquake that occur in the eastern margin of the Japan Sea by Earthquake Research Committee (2003). That information allow predicting the size of Tsunami.
In this study, the occurrence time of the earthquake was estimated with using earthquake prediction of the eastern margin of the Sea of Japan estimated by ERC (2003) as a reference.
Estimated from the results of the ERC (2003),Until next 50years in the sea of japan, the most likely area of occurring more than M7.5 earthquake is Sado island on northern ocean. Predicted the height of the Tsunami caused by this earthquake to reach the coastal Niigata, maximum wave height of the M7.5 Niigata Earthquake was 4.9 meters. However, it had a possibility that the height may be up to 5 meters or more because the seismic energy predicted was M7.8.
Relational expression of the depth and magnitude of earthquake attend Tsunami: M = 0.0044 D + 6.21 was teased out with to update the expression suggested by Noto: M = 0.0051 D + 6.21.In addition, the amount of water level fluctuation increasing when maximum seismic energy increases and it decreasing when seismic center becomes deep were found by a result considered from adding height of wave and water depth to judgment model of Tsunami. There is a possibility that the maximum water level variation is about a meter when M6.5 and it is 3 meters or over when M7.3. As a result, large Tsunami have more than 3 meters wave height occurrence needed more than 1000 meters water depth, and the maximum water level variation tended to decrease in more than 4000 meters water depth.
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