Loss functions for small marine vessels based on survey data and numerical simulation of the 2011 Great East Japan tsunami

Data for approximately 20,000 small marine vessels damaged by the 2011 Great East Japan tsunami, including information on motor types and tonnage, were collected and used to develop loss functions. The observed maximum tsunami heights from the field survey were used, and the maximum tsunami flow velocities from numerical simulation were obtained. Damage ratios were calculated, and loss functions were fit using linear regression analysis and log-normal distributions. The damage probability was significantly increased when the tsunami height was more than 2 m or when the flow velocity was more than 1 m/s. The results show that small vessels (weighing less than 5 t) with outboard motors were the most vulnerable. In addition, vessels at locations farther from the tsunami source had less damage because they were hit by smaller tsunamis with slower arrival times, which most likely gave them a chance to evacuate to deep sea. The results of this study, including the loss functions, will be useful for macroscale tsunami hazard and loss predictions involving small marine vessels.