Abstract
The Chikugo plain locates on the left coast of the Chikugo river which is the longest in Kyushu. The subsidence in the Chikugo plain has occurred since as nearly same time or a little earlier time as that in Saga plain. The scale is nearly the same as or larger than that in Saga plain. In the paper, on the basis of the investigation in the previous reports and new data, the ground subsidence in the coast area of Ariake bay, Chikugo plain, the decrease in the ground water in the deep ground layer, the subsidence of Ariake bay's bottom and the mining coal under the bay bottom were mentioned. It is concluded that the ground subsidence and recent expansion were caused by the water pumping for the coal mining under the bay bottom and the recovery of ground water after the close of the mining respectively.
