Following the March 11 Tohoku disaster, a coastal town in Shizuoka Prefecture has decided to create a special tsunami hazard map based on a hypothesized once-in-a-thousand-years tsunami.
Yoshida Town is in south-west Shizuoka and faces Suruga Bay. Although it is protected by a 6 meter breakwater, a tsunami of over 8 meters is now thought to be possible. The last major tsunami to hit the town was a 5~6 meter wave caused by the 1854 Ansei Tokai Earthquake.
Under the supervision of an associate professor from the Earthquake Research Institute of the University of Tokyo, the special map will be based on an earthquake of the same class as the 1498 Meio Nankaido Earthquake which had an estimated magnitude of 8.6 and caused a large tsunami in Suruga Bay and at Kamakura. Using historical records, the estimated height of the tsunami in Yoshida was 8.6 meters.
The City has been seeking feedback from local residents in order to make it more user-friendly. It is expected to be completed by November 30, 2011, and will be delivered to each household on December 6. This is the first one-in-a-thousand-year tsunami hazard map to be made by a town within Shizuoka Prefecture.
The Mainichi Shimbun, November 10, 2011.