TOKYO -- The venue for sailing at the 2020 Tokyo Olympics lies in an area from which it would be difficult to evacuate if hit by tsunami, experts say.
The Port of Shonan in the Kanagawa Prefecture city of Fujisawa, south of Tokyo, will serve as a venue for the sailing event during the Tokyo Games.
Data simulating the type of tsunami that would be generated if a megaquake hit the area shows that tsunami waves could hit the zone accommodating athletes and staff members about 90 seconds after a powerful earthquake. Moreover, the zone from which spectators are expected to view the sailing could be submerged approximately six to eight minutes after the quake. The Mainichi Shimbun obtained the simulation data through a freedom-of-information request.
The Tokyo Organising Committee of the Olympic and Paralympic Games maintains that athletes, staffers and spectators could evacuate from the area. Experts, however, say that evacuation would be difficult and they are underscoring the need to thoroughly explain the risks involved to spectators and others.
A private company was commissioned by the Kanagawa Prefectural Government to compile the data as part of a set of regular preventive measures to counter a disaster. The company compiled data on nine possible earthquakes whose focuses and scales were different from each other.
The Mainichi Shimbun obtained documents on the simulation of a magnitude-8.2 earthquake similar to the 1923 Great Kanto Earthquake that devastated Tokyo and surrounding areas.
Under the Cabinet Office's standards on possible damage from tsunamis, it would be difficult to evacuate if land areas were submerged to a depth of 30 centimeters, which would cause casualties. If the water depth were 1 meter, the death rate in affected areas would be 100 percent. The data that the Mainichi Shimbun obtained is based on the Cabinet Office standards.
The simulation divides the Port of Shonan area into 10-meter-square blocks and predicts how many seconds it would take tsunami waves to hit each block after an earthquake struck, taking into consideration each block's altitude and geographical features. The simulation shows that the water in areas for athletes and staff members would be 30 centimeters deep, or even up to 1 meter deep, approximately 90 seconds later -- when the Japan Meteorological Agency usually announces Japanese intensity scales in affected areas.
Roughly six minutes after the temblor, water in the zone around the storm surge barrier, where spectators will be viewing the event, would be submerged by 30-centimeter-deep water. About eight minutes after the quake, tsunami water in most of the port area would be at least 1 meter deep.
A former Japanese Olympian says that when yachts leave and come back to the port, athletes and staffers need to be in the area where tsunami water would be 30 centimeters deep about 90 seconds after a megaquake. Nobuaki Shimizu, a professor at Aichi Prefectural University who is versed in crisis management including evacuation from tsunamis, warns, "Even athletes wearing life jackets could be injured by floating objects. Staffers without such jackets could drown."
The organizing committee had initially intended to accommodate 5,000 spectators on the east side of the port by setting up seats at the zone, but reduced the number to 3,300 as a measure to counter a tsunami. Still, including 2,100 athletes and staffers and 300 reporters, a total of 5,700 people could be in the area. A public relations official at the organizing committee repeated that all the 5,700 could safely evacuate. The organizing committee plans to accommodate evacuees at six facilities designated as shelters including one on a hilly area. However, the committee declined to specify the evacuation route.
The sailing event in the Tokyo Games is scheduled to be held from July 26 to Aug. 5.