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  The earthquake of the magnitude-9.0 and the ensuing crisis at the Fukushima Daiichi nuclear power plant in March 2011 prompted sweeping reviews of Japan's disaster preparedness and criticism over apparent failures to take into account potential risks. Based on researches following the catastrophes, Japanese government revised tsunami projections in a report posted on a government website. While the earlier forecast in 2003 put the potential maximum height of a tsunami run-up at less than 20 meters, a governmental panel of experts in Japan recently reported that the occurrence of a magnitude-9.0 earthquake in the Nankai trough, which runs east of Japan's mainland of Honshu to the southern island of Kyushu, might generate a tsunami run-up with height more than 34 meters, inundating much of Japan’s Pacific coast.

 

  Consequently there is a considerable concern in China and Korea on the potential danger of the Nankai Trough-originated tsunami. The tsunami simulation due to probable Nankai earthquake is performed to determine the effect on Chinese and Korean coasts. The dataset of 11 initial conditions provided by Japanese Government was used. The 3D finite-difference Princeton Ocean Model (Mellor, 1998) using the spherical coordinates is applied here to simulate tsunami wave propagation in vertically 10 sigma layers. Variable nesting domains are constructed with the variable grid resolution of 4.5 km to 50 m. Tsunami propagation is computed cooperatively with Sungkyunkwan University (SKKU) of Korea.

 

  The simulation shows that the tsunami waves propagate southwestward and then diffracted in the clockwise direction at the south of Kyushu, heading for Cheju and the southern coast of Korea. After occurrence of Nankai earthquake, tsunami waves are expected to reach at Cheju island in about 3.5 hours and at the southern Korea coasts in 4 hours. It is implied from the long wave theory that the mean propagation speed of tsunami waves is about 70m/s in the average water depth of 500 meter. It has been noted in the course of simulation that more significant amount of tsunami waves appears to propagate to the Chinese coast, sweeping out the wide shelf area of East China Sea. Further simulation studies are underway taking into account the tidal stirring effects and will be reported soon.