It is the last thing that will be left of the shelves that have been laying dormant since the Fukushima disaster.
A new study has found that the shelves on the easternmost shelf of the Japanese coast have collapsed, and that their collapse could potentially destroy the entire shelf system.
“It is now the end of the shelf system,” says Masami Yamamoto, a professor of marine engineering at Kansai University, the country’s main research university.
Yamamoto’s team had been monitoring the health of the westernmost shelf since its discovery in 2015.
It was the only shelf system that had not collapsed.
In January, the team began collecting data and monitoring the condition of the entire system, which has been in the process of being replaced for decades by a series of smaller, seaworthy structures.
This new study, published in the journal Geophysical Research Letters, found that a number of these larger structures had collapsed, while the remaining two were in a “stable condition”.
“We have to be very careful with these data,” Yamamoto says.
“The system we have has been working for more than 20 years, and the data that we are collecting is important, but it is still very fragile.”
The new findings could help researchers to determine how much time is left for the system to recover.
It also comes at a time when the Japanese government is looking to improve its ability to deal with the effects of the Fukushima Daiichi nuclear disaster, which left an estimated 1.2 million people in the country homeless.
The government is currently planning to spend around $10bn (£7.3bn) to upgrade a number the country has already invested in.
But it could take several years for the systems to completely recover.
In the meantime, Yamamoto is focusing on other research projects, including studying the impacts of climate change on the Japanese coastline.
The new study is the latest effort to highlight the health and resilience of the northernmost shelf system, in particular as the country is already dealing with an increased number of typhoons.
“In a very short time, we have seen a large number of storm surges,” says Yamamoto.
“This system has been very resilient.”
The team is now studying the effects the storm surge would have on the northern shelf.
If the system collapses, Yamawa hopes that it will allow the seawater to slowly recover and allow for the shelf to be able to recover as well.
“If the seawaters don’t collapse, we could see the seawall rebuild,” he says.
The report concludes that the western shelf system is in “stable” condition, but that the southernmost shelf could collapse, and so the rest of the system could not be fully recovered.
“We should not forget that the system we know is not the last system, so the collapse of the rest could also lead to the collapse in the southern system,” Yamomada says.
This article appeared in Al Jazeera’s Science and Health section, with additional reporting from Mark Gaille.