Photo/IllutrationA decorated wall in the Kiyotosaku tunnel tomb in Futaba, Fukushima Prefecture, was dotted with a white substance that is believed to be salt, taken in 2014. (Asahi Shimbun file photo)

  • Photo/Illustraion

Archeologists and conservationists are battling to preserve ancient tombs built in Japan between the fifth and eighth centuries after human intervention and climate change triggered a deterioration in their conditions.

The experts are struggling to strike a balance between academic, public and conservation interests in their plight to protect the precious archeological sites that have been preserved for hundreds of years undisturbed.

The sites, referred to generically as “decorated tombs,” have interiors adorned with drawings, colorings or reliefs. More than 600 such tombs have been found all over Japan.

When the Agency for Cultural Affairs conducted a survey in 2012 on 73 decorated tombs in 15 prefectures, which are designated as national historic sites, they found signs of deterioration in 35 of them.

Their decline was due to factors such as changes to the environment inside the tomb and the growth of mold.

Among other places in Japan, the municipalities affected by the 2011 Great East Japan Earthquake and tsunami in northeast Japan are facing a multitude of challenges and difficult decisions to make. Only about three kilometers away from the crippled Fukushima No.1 nuclear power plant, the Kiyotosaku tunnel tomb is an important example of such tombs built in the seventh century in Futaba, Fukushima Prefecture, and is listed as a national historic site. Its excavated walls were decorated with various patterns and pictures of a human and animals painted with red pigment.

Around 2007, the surface of the tomb’s inner wall was found dotted with a white substance. Salt from the earth had crystalized due to the rise of the temperature outside.

Futaba’s education board started work to stop further deterioration in 2010, but it was halted when the 2011 earthquake and tsunami hit, followed by the Fukushima nuclear plant accident. The tomb is in the "difficult-to-return zone," the highest level of the government’s evacuation policy around the plant.

Four months after the accident, Takamitsu Yoshino, the education board’s chief researcher, entered the tomb wearing a protective suit. The painting was intact, but a device to measure temperature and humidity, which used to transmit readings, had stopped working due to the power cut after the accident.

It is also feared that tree roots are growing into the cave, but no fundamental conservation measures have been implemented since the disaster.

“For the evacuees of Futaba, these cultural properties are reminders of their hometown. I really want to save and pass on the piece of town’s history,” said Yoshino. He visits the tomb every few months to keep an eye on its condition.

While Futaba’s officials are struggling to prevent further deterioration, another local government also in the quake-hit area is being forced to take more drastic measures.

In May 2015, a surprise archeological discovery was made in the coastal town of Yamamoto, Miyagi Prefecture, north of Fukushima Prefecture, where about 40 percent of the town was inundated by the 2011 tsunami, and 636 residents were killed.

Yamamoto town government officials found 54 tunnel tombs from the ancient Asuka Era by mere chance in the course of searching for a plot on high ground to build a new settlement for the town.

One of the tombs had a variety of line drawings chiseled on to the inner wall of its tunnel. Several human figures and birds were depicted, along with other items, including a kind of container for arrows and a fan used by nobility.

The sheer variety within the tomb made it an unprecedented find in the Tohoku region.

However, after the discovery of the long-sealed chamber, the change in humidity meant that the soft sandy wall faced imminent deterioration.

The Yamamoto government decided not to pursue conservation of the wall at the site, as adequate technology does not exist to halt that kind of deterioration, and instead opted to prioritize the rebuilding of the town.

With assistance from the culture agency and experts from Nara National Institute for Cultural Properties, the town government has started exploring ways to develop a new method to remove the surface of the wall and allow it to be preserved off-site.

“It was a difficult decision to make. We hope to save the wall by using our collective wisdom, and keep it as our townspeople’s pride,” said Saburo Saito, a member of the education board of Yamamoto town government.

The removal of ancient artwork from their original sites for the sake of conservation is always controversial, as it is virtually irreversible with today’s technology.

Authorities around Japan are looking after and conserving decorated tombs on-site, but a breakthrough in technology is needed to beat the threat of ever-changing climate conditions, said Masaaki Sawada, a professor of conservation technology at Tohoku University of Art and Design.

“There is a huge challenge to overcome (to protect archeological sites) in technology development against global warming and other climate changes,” Sawada said.

For many decorated tombs around Japan, life-size replicas are often exhibited for tourism and education purposes. Building digital archives of tombs using 3-D scanning technology is one of the ways of sharing the precious archeological sites with the public.

Educating the public and encouraging them to treasure the cultural properties as collective assets of the people is an important task that the archeologists and conservationists need to consider. Balancing the needs for conservation and the benefits of public exhibition is ever more important.

(This article was written by Kazuto Tsukamoto and Kunihiko Imai, a senior staff writer.)