Remains of excavated floor delays seismic reinforcement work on A-bomb Dome

by Masanori Wada, Staff Writer

On February 1, the City of Hiroshima announced that slabs of concrete presumed to be the remains of the floor of the Hiroshima Prefectural Industrial Promotion Hall (the A-bomb Dome building before the atomic bombing) were found at two locations on the A-bomb Dome grounds. The A-Bomb Dome, which is located in Naka Ward and has been designated a World Heritage site, is now undergoing seismic reinforcement work. Following the appearance of the concrete floor, the City of Hiroshima is now planning to carry out further investigations on the size of the floor and various related matters. As a result, the construction work, which was scheduled to end in late March, will be extended by a few months.

According to the city’s Park Development Division, two slabs of concrete were found on the north side of the showroom of the former Industrial Promotion Hall. One is rectangular and approximately two square meters in size and the other is an L-shaped piece of approximately three square meters. These slabs were excavated at the end of December last year as workers were removing dirt and rubble from a depth of between 10 and 50 centimeters beneath the ground to begin the work of enlarging the foundation areas for the nearby supports.

Similar slabs of concrete floor were found at the staircase hall just below the dome during the research work undertaken prior to the A-bomb Dome preservation work in 2002. The city’s Park Development Division said that they had predicted from past construction records that no remains would be excavated from the ground at the current reinforcement work site. Since the A-bomb Dome’s designation as a World Heritage site, it has been impractical to dig out the whole area surrounding the structure. At most, the city will make three-dimensional images of the two locations from which the remains were excavated and create a research record of the findings. After the investigation, the land will be filled back in, then the foundations for the supports will be enlarged so that the enlarged areas will cover the concrete remains.

The City of Hiroshima began its first seismic reinforcement work on the A-bomb Dome last December, and the work to fortify the brick walls with structural steel is now under way. The brick walls could collapse at three locations on the north and south sides of the walls if an earthquake of a low 6 magnitude should strike the city. The reinforcement work at two locations on the north side, which has been suspended since the remains were found, will resume in April at the earliest.

(Originally published on February 2, 2016)