The defunct Shirahama district 1 evacuation tower in Toyo, Kochi Prefecture, stands at 7.1m, which is 0.8m short to clear the revised maximum flood projection of 7.9m. - Photo: The Japan News/ANN
KOCHI/WAKAYAMA, (Japan): Several tsunami evacuation towers built in preparation for a Nankai Trough earthquake have, after their construction, been reassessed as too short or too weak. Measures have been taken for most but not all of these structures.
Assessments revealed that 22 towers in 14 municipalities across five prefectures, including Wakayama and Tokushima, did not meet the required height or strength standards. The assessments were made based on revised damage projections for a Nankai Trough quake and other information.
While a response has been taken for 18 of these structures, including rebuilding or reinforcing them, there are as yet no plans for the remaining four towers, which are in Toyo, Kochi Prefecture, and Kushimoto, Wakayama Prefecture.
Tsunami evacuation towers are designed for rapid, temporary evacuation to higher elevation in coastal communities where it is otherwise not possible to reach safe areas in time.
Typically, these structures consist of an elevated platform supported by a steel framework, and they are several meters or more in height. They were widely adopted after the March 2011 Great East Japan Earthquake.
Previously, there were fewer than 50 towers of this kind nationwide, but that grew to 550 by 2023, according to a Cabinet Office survey.
In Toyo, a durability study on the town’s evacuation towers concluded this spring that three structures were too weak to withstand incoming tsunami.
The town plans to rebuild the Shirahama district No. 1 evacuation tower, which was completed in March 2010 and can accommodate 130 people.
The structure lacks the requisite strength, and at 7.1 meters tall, it is 0.8 meters short to clear the revised maximum flood projection of 7.9 meters.
Until the tower is rebuilt, the third and fourth floors of a four-story community center, located about 250 meters northwest of the tower, are serving as an evacuation area.
A wooden sign on the tower now directs people to the temporary evacuation site. Yusuke Inoue, the district’s 71-year-old resident, expressed the anxiety felt in the community. “Many elderly residents live nearby,” he said.
“While I understand that reconstruction requires significant funding and time, I hope it happens as soon as possible.”
Meanwhile, the town has yet to decide on a course of action for two other towers that were found to be too weak, though they are sufficiently tall.
While rebuilding these towers is an option, Mayor Masahito Nagasaki noted the financial obstacles.
“The estimated cost runs into hundreds of millions of yen. It is difficult for the town to manage this burden alone, so we are seeking financial assistance from the prefectural government.”
Revised projections for tsunami damage made in 2013 revealed that five towers in the towns of Tanabe, Shirahama, Susami and Kushimoto in Wakayama Prefecture were not tall or strong enough.
Two towers in Kushimoto, one short by 0.8 meters and the other by 1 meter, are still serving as evacuation sites. The town has not been able to secure suitable land for new towers or identify alternative evacuation sites.
“When the tower was built, I felt relieved. I thought I’d be safe,” said a woman in her 70s who lives near one of the structures.
“Finding out that it was [too short] came as a real shock. Now that I’m having trouble walking, that tower is my only hope.”
The town is considering removing the towers from its list of official evacuation sites. “We must inform the public of the risks and quickly find a solution,” a town official said.
All municipalities have taken measures for their inadequate towers except for Toyo and Kushimoto, with many opting to build new towers near the old ones.
Shimanto in Kochi Prefecture installed two new evacuation towers between 2013 and 2014, while in Wakayama Prefecture, Susami built one in 2015 and Tanabe finished its own in 2021.
Shirahama, Wakayama Prefecture, took its structurally deficient tower out of service in 2016 and, in 2019, deployed a 25-passenger tsunami lifeboat alongside it. - The Japan News/ANN
