Model of Predicting Multi Tsunami Scenarios considering Large Slip Zone and Super Large Slip Zone and Its Application in the Nankai Trough

Abstract:

In the 2011 Tohoku Earthquake Tsunami Disaster, the actual tsunami heights had exceeded the estimated heights extremely and the underestimation caused serious damages in Japan. To reduce such a risk, multi tsunami scenarios were examined especially considering Large Slip Zone (LSZ) and Super Large Slip Zone (SLSZ) suggested by the Cabinet Office, Government of Japan. In the Nankai trough, 11 tsunami faults were assumed. Even if their magnitudes are same, the tsunami heights attacking coastal cities are quite different due to locations of LSZ and SLSZ. For example, the difference is about 5 meters at Tanabe city, Wakayama prefecture. Therefore, the multi tsunami scenario considering LSZ and SLSZ is very important in the tsunami disaster mitigation. However, it is not cleared how to consider the uncertainly in tsunami scenario. A model of predicting the scenarios is proposed in this study. The model consists of areas, dislocations, shapes, locations of LSZ and SLSZ, and the initial crack location. A couple or two couples of LSZ and SLSZ are examined. This model can be applied to any plate boundaries in the world. And it can make the multi tsunami scenario systematically after determining some parameters such as the ratios of area and dislocation of LSZ to a tsunami fault. The model was applied for the Nankai Trough to predict multi scenario of future large tsunamis and its detailed procedure was shown.