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Tsunami on the northern coast of Noto Peninsula uplifted by the 2024 Noto Peninsula Earthquake is not well understood because of (1) difficulties of tsunami field survey due to the destruction of roads to
access the northern coast, (2) seawall effect of the uplifted coast, and (3) difficulties of distinguish
between traces of the tsunami and wind waves which have almost the same trace height, etc.
This study aims to understand the actual situation of the tsunami on the northern coast. Therefore, first, places judged to have tsunami trace are identified through inspection of aerial photographs and video pictures taken immediately after the tsunami attack, and then heights of the tsunami traces are measured. Effectiveness of the method is comfirmed by applying the method to places where the tsunami trace heights are already obtained. Next, a simple static tsunami model which has initially a uniform water level rise caused by a uniform coastal uplift in the cross-shore direction over a uniformly sloping beach is proposed and analysed theoretically. It is indicated through a theoretical analysis based on the nonlinear shallow water theory that the water of the uniformly raised area in the static tsunami model just flows out offshore and does not oscillate on shore. This phenomenon is comfirmed from a CCTV footage taken at the Wajima port and so on. These suggest that main part of the tsunami on the northern coast is originated from somewhere else. Aiming for a rough estimate of the initial water level rise in the static tsunami model, a field survey on the distribution of the upper end level of the reef whitening, i.e. vertical displacement is also conducted along the northern coast.
Research papers (academic journals)
