Written by Eric Cheung Junko Ogura, CNN Tokyo

An old garment depot that survived the atomic bombing of Hiroshima, and provided temporary shelter to victims within its concrete walls, could be partially demolished by local authorities 75 years later.

The former Hiroshima Army Clothing Depot was one of the largest buildings left standing after the US military dropped an atomic bomb on the Japanese city during World War II, immediately killing more than 70,000 people. The depot was 2.7 kilometers (1.7 miles) from the blast hypocenter.

More than 90% of the structures in Hiroshima were either destroyed or damaged by the blast and fire, according to the Campaign for Nuclear Disarmament. Images taken from the air in the aftermath of the bombing show the totality of the destruction, with only a handful of steel and concrete buildings left standing.

A photo taken on June 26, 1946 show the ruins of Hiroshima nearly a year after the US military dropped an atomic bomb on the Japanese city. Credit: Bettmann/Bettmann/Bettmann Archive

The depot consists of four building, each 15-meters high, built from concrete reinforced with steel bars. The first three units, each almost 5,600 square meters large, are owned by the Hiroshima government. The fourth is slightly smaller at 5,000 square meters and is owned by the national government, according to the Hiroshima Peace Media Center. None have been occupied since 1997.

However, the site's future is now uncertain. The Hiroshima government has proposed demolishing two buildings for public safety reasons, after a recent survey revealed they may be at risk of collapse during major earthquakes.

The study , conducted by local authorities in 2017, found the depot "had a high risk of collapse" in the event of a large earthquake measuring 6.0 on the Richter scale, because it stands on soft ground and consists of few partition walls to support the structure.

In a notice posted last week, local authorities suggested renovating the building closest to the site of the explosion, as it is perceived to have the "greatest historical value." However, the notice added that it was unclear whether the building would be safe to occupy even after renovations.

An interior shot of the former garment depot. Credit: Hiroshima Government

Authorities in Hiroshima said they were prompted to take action after a magnitude 5.3 earthquake last year damaged roads and buildings in Osaka, some 300 kilometers (186 miles) away from the city.

Hiroshima itself also has experienced earthquakes -- a magnitude 6.4 earthquake in 2001 also damaged train systems and phone services.

"The buildings sit in the residential area and considering the risk of collapse, it is the painful choice," Taiki Adachi, an asset management officer at the Hiroshima government, told CNN in a phone interview.

Adachi said it would be too expensive to add quake-resistant features for all three buildings, which would come to an estimated 8.4 billion yen ($76.7 million). Instead, the more cost-effective approach would be to demolish two units and keep the most valuable one by reinforcing the walls and roof, which would only cost 800 million yen ($7.3 million).

He said a final decision has not yet been made, and the government is inviting the public to submit feedback on the proposal until February next year.

The building's exterior. Credit: Hiroshima Government

Keeping history alive

Hiroshima mayor Matsui Kazumi said the buildings were too important to knock down.

"The a-bomb buildings are a silent witness to tell the historical facts of the bombing and the misery of the a-bomb damage. I think they are a valuable asset," he told reporters Thursday.

"Hiroshima city understands the need for safety measures and financial resources measures, but we are asking Hiroshima prefectural office to preserve entire buildings as much as possible."

Iwao Nakanishi was 15 years old and working at the depot when the bomb dropped. Several years ago, he founded the Committee for the Preservation of the Former Army Depot.

Now aged 87, Nakanishi told CNN the buildings contain valuable lessons about the importance of peace.

"It is unacceptable to dismantle them," he wrote in an email. "There is a significant historical value to pass on the lessons of tragedy to future generations."

The group organizes seminars and site visits where survivors share stories of their experience and spread the message of peace, according to its website.

The depot was one of the largest buildings that survived the atomic bomb, and survivors say it is too valuable to be torn down. Credit: Kyodo via AP

More than 15,000 residents have also signed an online petition calling on the Hiroshima government to preserve the depot.

Naori Fukuoka, who started the petition, urged the government to utilize the facility as a historical and educational center for the public.

Old army depot

First opened in 1913, the depot was used for producing and storing military uniforms for Japanese soldiers before and during World War II, according to Adachi, the Hiroshima government official.

The building is characteristic of the architectural style of the Meiji period (1868 to 1912), which primarily used bricks and stones as construction materials, according to the Hiroshima government website. Architects used both reinforced concrete and bricks to strengthen its structure, which was uncommon at that time, it said.

After surviving the atomic blast in 1945, the buildings were converted into teaching centers for a higher education institution that later became the education faculty of Hiroshima University. Less than a decade later, in 1956, it was rented to logistics company Nippon Express, before being abandoned in 1997.

Hiroshima considered converting the depot into a cultural museum, but the plan was dropped after surveys showed that the structure may be unsafe in the event of an earthquake.

The building's damaged exterior. Credit: Committee for the Preservation of the Former Army Depot

The Former Army Clothing Depot is one of the largest of 86 existing structures in the city that survived the atomic bomb, according to Hiroshima government.

The most famous structure, the Atomic Bomb Dome, was originally an exhibition hall that was completed in 1915. It is now part of the peace memorial museum in Hiroshima and a UNESCO World Heritage Site.

However, not every building that survived the atomic bomb has been preserved. Adachi told CNN that, since 1996, at least 10 privately-owned buildings have been demolished due to aging.

Fukuoka, who started the petition, wrote that the depot's preservation was especially important for Japan to pass on the message of peace to the next generations.

"Many survivors of the atomic bomb have shared their voices here," he wrote in the petition. "Some history can only be preserved when it is kept in its entirety."