The Environment Ministry says nearly 6,000 square kilometers of land across Japan have subsided by more than 2 centimeters in the last fiscal year.
The figure is about 1,000 times greater than in the previous fiscal year that ended March last year, and the largest-ever since records began in 1978.
Municipal organizations that extract underground water assess land subsidence on a regular basis.
About half the 30 tested areas in 20 prefectures were recorded as sinking more than 2 centimeters. This level is judged to have a potential impact on buildings’ stability.
The ministry says Kesennuma in Miyagi Prefecture sank deepest by 73.8 centimeters, followed by Ichikawa in Chiba by 30.9 centimeters. Tsukuba in Ibaraki sank by 15.2 centimeters.
Seven areas subsided by more than 10 centimeters. These lie in Tohoku, and in the Kanto region that includes Tokyo.
The ministry officials say the subsidence is attributable to last year’s March 11th earthquake. They have expressed concerns over the spread of subsidence and further damage to buildings.