Mito City Hall in Ibaraki Prefecture was seriously damaged by the March 11 earthquake. Results of a recent earthquake-resistance inspection found that the building could collapse if it is hit by another earthquake with a seismic intensity of 6 or higher.
Should the City decide to repair the building by installing a base-isolation system, the repair costs are estimated to reach 7 billion Yen (91 million USD).
During the earthquake, the foundations of the 7-storey building sunk to uneven levels with the most severe damage occurring to the structure of the 4th floor. The City’s fire and waterworks buildings were also damaged and require repairs. The City is also considering demolishing and rebuilding the structure and plans to conduct a local opinion poll in December before deciding on a course of action.
The City Hall building was completed in 1972. In 1996 an earthquake-resistant inspection was carried out and the building was found to have a Seismic Index of 0.32 ~ 2.67, which meant that the building would collapse or be in danger of collapse if hit by an earthquake with a seismic level of upper 6 (read about Japan’s seismic intensity scales ). The March 11 magnitude 9.0 earthquake produced a seismic intensity level of lower 6 in Mito City.
The Yomiuri Shimbun, November 22, 2011.