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Tokyo Olympic sailing venue would be difficult to evacuate during tsunami: expert


An expert well versed in the evacuation of those vulnerable to disasters has pointed out that it would be difficult to evacuate the thousands of expected spectators from the venue of the 2020 Tokyo Olympics sailing competition in the event of a massive tsunami generated by a powerful earthquake.

His view counters Tokyo Games organizers' assertion that it is possible to evacuate some 5,700 spectators from the venue at the Port of Shonan in the Enoshima district of Fujisawa, Kanagawa Prefecture, south of Tokyo.

If land areas were submerged to a depth of 30 centimeters, it would cause casualties, and if the water depth were 1 meter, the death rate in affected areas would be 100 percent under the Cabinet Office's standards on possible damage from tsunami.

Kanagawa Prefectural Government data simulating a magnitude-8.2 earthquake similar to the megaquake that hit the Kanto area in 1923 shows that the areas where spectators would likely stay would be submerged to a depth of 30 centimeters about six minutes after the temblor and the depth would rise to 1 meter in most of the affected areas within around eight minutes.

There is as much as a 6% chance of such an earthquake occurring within 30 years, according to government predictions.

Nobuaki Shimizu, professor at Aichi Prefectural University who is well versed in the situations of infants and sick and injured people who are vulnerable to natural disasters, recently inspected the area around the venue for the Tokyo Games' sailing event.

Shimizu paid attention to the east edge of a storm surge barrier at the Port of Shonan where spectators can see yachts leaving and arriving. If a quake strikes when spectators are in that area, they will have to descend stairs when they move from the top of the barrier, which is over 6 meters tall, to the sailing center currently under construction, which serves as the nearest evacuation shelter.

Noting that only two people could stand side-by-side on each step, professor Shimizu pointed out that it is impossible for elderly people and those using wheelchairs to be supported from both sides on the stairs.

Shimizu walked at a speed similar to that of elderly people and arrived at the sailing center five minutes and 30 seconds later. It took him six minutes and 20 seconds to arrive at Shonan Coast Guard Station, another nearby facility designated as an evacuation shelter.

Shimizu explained that it takes a further minute to move up and down inside buildings.

Data simulating a megaquake suggests that the area would be submerged by tsunami waves at least 30 centimeters high before spectators could arrive at these evacuation centers.

The organizing committee of the Tokyo Games has declined to show the location of the spectators' stand or evacuation routes.

Believing that many spectators would gather at the center of the storm surge barrier, Shimizu assumed a route from the area to higher ground where the largest of all six evacuation shelters is situated as "evacuation route 2." The professor walked on a section of a 5.4-meter-wide promenade for about 300 meters and arrived at a parking lot about six minutes and 10 seconds later. The prefectural government simulation shows that the water depth would reach about 1 meter by that time. The road leading to the top of the hill includes a narrow section only about 80 centimeters wide as well as steep stairs.

"It's just like mountain climbing. Buildings along the route could collapse due to a quake," the professor said. "It would likely take at least one hour before thousands of spectators could reach here."

Olympics organizers have no plan to build or designate more evacuation shelters besides the six already-designated structures.

An individual linked to a sports organization said countermeasures against tsunamis are not taken into account in selecting the venues for Olympic events.

(Japanese original by Itsuro Goto, Special Reports Group)

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