A Century of Countermeasures Against Storm Surges and Tsunamis in Japan

The countermeasures against storm surges and tsunamis in Japan are briefly reviewed covering roughly the last century. In spite of 22,000 deaths resulting from the Meiji Great Sanriku Tsunami just before the 20 th century, neither central government nor local governments took effective countermeasures. The first positive countermeasures were taken by the central and local governments after the Showa Great Sanriku Tsunami and the Muroto Typhoon in early 1930s. The Seashore Act was enacted in 1956. After the 1959 Ise Bay Typhoon and the 1960 Chilean Tsunami, it has been the general practice to construct coastal dikes 5-6 m high as defense countermeasures. Tsunamis exceeding this height are met by combining structures, tsunami-resistant town development and defense systems. Quantitative tsunami forecasting announced by the Japan Meteorological Agency is currently state-of-the-art globally in terms of swiftness, preciseness and details.