Mechanisms for Damage and Failure from the Great East Japan Tsunami - Tohoku, Japan Earthquake and Tsunami of 2011 - page 60

Figure 63. Otsuchi tsunami wall — Flow
in the corner resulting in overtopping
and large scour hole inland of the wall

Figure 64. Taro wall — Failure at
change in wall angle

Figure 66. Omoto (shoreside scour)

Figure 65. Kojirahama (shoreside
scour)

3.9 Erosion

Beach erosion and erosion around the exposed foundations of coastal structures result
from sediment scouring caused by the incoming tsunami wave's high water
velocities, water turbulence, and supercritical flows during the tsunami's runup and
backrush (draw-down) due to the immense flux of displaced water and the high
energy involved (Figure 67). Figures 68 - 71 show examples of structures affected by
erosion.