TSUNAMI DAMAGE TO OIL STORAGE TANKS IN THE MW9.0 2011 TOHOKU, JAPAN EARTHQUAKE

The Mw9.0 2011 Tohoku, Japan earthquake tsunami damaged 418 oil storage tanks located along the Pacific coast of the Hokkaido, Tohoku, and Kanto Districts of Japan. A wide variety of damage was observed, including movement and deformation of the tank body, scouring of the tank base and ground, and movement or structural fracture of the pipe. In total, 157 of the 418 tanks were moved by the tsunami. By comparing the severity of damage with the inundation depth of the tsunami experienced by the oil storage tank, a fragility curve projecting the damage rate for plumbing is presented, and a rough but easy-to-use method of predicting tsunami damage to an oil storage tank from a given inundation depth is also presented: (i) for inundation depths of 2-5 m, tanks suffer damage to their plumbing, and small tanks (capacity < 100 m(3)) and empty larger tanks may be moved; (ii) for inundation depths of greater than 5 m, most tanks are moved. The validity of the previously-proposed tsunami tank-movement prediction method is first examined. A comparison of the method's piedictions with the actual damage data from the 2011 Tohoku earthquake tsunami indicates a high hit rate of 76%.