kaoru NAGASAWA
Propagation characteristics of Tsunami caused by Tohoku-Pacific Ocean Earthquake
Naoyuki INUKAI
Tohoku-Pacific Ocean Earthquake occurred on 11 March 2011. Tsunami caused by this earthquake was far beyond traditional expectations. To make a giant tsunami disaster prevention measures to exact, it is necessary to know the propagation characteristics of tsunamis caused by Tohoku-Pacific Ocean Earthquake. In this study, we made numerical calculations of the tsunami on a small area and a large area.
The calculation of large area gives the ground displacement as initial displacement. This calculation of ground displacement was used the method of Okada (1992). The calculation of small area use the tsunami waveforms observed by GPS wave gauge. We were used a computational model that the explicit difference about equations of motion and equations of continuity in the plane two-dimensional that was created in polar coordinate system.
The results of large area are follows.We compared the height of the calculation and the observed value, up to 60 minutes was able to reproduce relatively well. Kushiro and Choshi saw that the wave to reached leading wave after the backwash of micro from water distribution map.
The results of small area are follows. As a result, the value near an observed value was able to be acquired. Therefore, we think that the reproducibility of the tsunami by calculation is well. The propagation situation of tsunami was checked using this result. We have grasped how wave quantity became high around in the Yoneda area in Nodaˇˇvillage where 38-m ascension marks were checked from the water level distribution map. Moreover, we checked the velocity and water level in the place with damage, such as a house outflow and destruction of a bank. As a result, we have grasped quantitatively that the difference of damage arose in Kuji and Noda by the difference in the velocity or a water level.
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