The Yomiuri ShimbunTokushima is the only at-risk prefecture to have designated “tsunami warning areas,” and more than half of the prefectures legally required to estimate how much land is at risk of flooding by tsunami have yet to do so, a Yomiuri Shimbun investigation has found.
Failure to conduct this work stems from deep-rooted concerns among local governments and residents that such designations could deflate land prices and tarnish the image of these areas, but some experts have warned that acting quickly must take priority, because there will be no time to put safeguards in place after a disaster has struck.
After the experience of the Great East Japan Earthquake and ensuing tsunami that devastated the Sanriku coast in the Tohoku region on March 11, 2011, the Law on Making Local Areas Resistant to Tsunami was fully enacted in June 2012. Based on the law, prefectures where tsunami are expected to cause significant damage can designate tsunami warning areas.
However, the Yomiuri investigation revealed that only Tokushima has earmarked such areas, and that 20 of the 39 prefectures required to survey which areas could become inundated have not done so.
The law requires local governments to estimate and take countermeasures against “a maximum-class tsunami generated in a worst-case scenario, including at high tide.” Based on this research, prefectural governments are to estimate how much land could be submerged and designate tsunami warning areas where major damage is expected, and “tsunami special warning areas” where there is even greater danger.
The Yomiuri surveyed the 39 prefectures in Japan with a coastline. Nineteen prefectures, including Ibaraki, Tokushima, Kochi and Miyagi, had prepared such estimates, although some were completed only for certain areas.
Tokushima had predicted that a massive earthquake in the Nankai Trough running south of Honshu could generate a tsunami more than 20 meters high that could strike the prefecture and kill 31,300 people. In March 2014, Tokushima Prefecture established warning areas covering about 200 square kilometers.
“We wanted to ensure that awareness of this danger was reliably passed on to future generations,” a prefectural government official explained.
Although none of the other prefectures have completed such designations, Yamaguchi Prefecture is scheduled to do so this month, and Shizuoka Prefecture “has compiled proposals for designated areas, and is requesting that local governments consider them.”
However, at this stage, not a single special warning area has been designated by any prefecture. In these areas, local government ordinances can restrict home construction, and prefectural authorities can even recommend residents move to another area. Tokushima Prefecture said it had delayed making any such designation because “we are making efforts on this as a long-term matter, while we keep in step with town-building plans.”
Many reasons were given for not having specified special warning areas. A representative of the Osaka prefectural government said, “Many residents are worried that this could cause land prices to fall,” while a Kochi prefectural government representative said, “Placing restrictions on the construction of homes and hospitals would have a huge impact on urban development.”
The prefectures of Miyagi, Iwate and Fukushima were hit hardest by the March 2011 disaster, which generated “unexpectedly large” tsunami and left more than 18,000 people dead or missing. In these areas, too, estimates on which areas would be submerged have been put off until more progress is made on reconstruction work. “We can’t make an accurate forecast until the construction of seawalls and work to elevate ground has been completed,” a spokesman for the Miyagi prefectural government said.
The Tokyo metropolitan government said it was already implementing countermeasures based on estimates it had calculated independently of the tsunami law.
In August 2014, the central government predicted the height of tsunami that could hit prefectures facing the Sea of Japan coast. However, many prefectures along this coast have been slow to respond and address the potential danger, the Yomiuri investigation found.
“Each region has its own conditions and circumstances, so we can’t impose a uniform time frame on them to make these designations,” an official of the Land, Infrastructure, Transport and Tourism Ministry said.
Yoshiaki Kawata, a member of the government’s Central Disaster Prevention Council who has been involved in estimating the damage that could be caused by a major earthquake along the Nankai Trough and other quakes, is urging prefectural governments to give this work greater priority.
“Many people died in the Great East Japan Earthquake because the dangers of tsunami had been forgotten,” said Kawata, who is a professor at Kansai University. “If warning areas aren’t designated, I fear this danger will be forgotten as the generations change. Worries about falling land prices and population outflows are understandable, but I want local government leaders to remember the catastrophe that happened four years ago and make even a little progress with designating these areas.”
Local governments in tsunami warning areas are obligated to compile tsunami hazard maps, and operators who buy, sell or lease out land in these areas must explain to customers about this designation