SINKHOLES AND SUBSIDENCE ABOVE ABANDONED MINES AND QUARRIES CAUSED BY THE GREAT EAST JAPAN EARTHQUAKE ON MARCH 11, 2011 AND THEIR IMPLICATIONS

抄録

The Great East Japan Earthquake with a moment magnitude 9.0 occurred on March 11, 2011 and shook almost the entire Japan. There are many abandoned lignite mines in the close vicinity of the epicentral areas such as Miyagi and Iwate prefectures and many sinkholes occurred following the earthquake. There are also reports on the delayed occurrence of numerous sinkholes in the same areas. In addition, some collapses and subsidence occurred above abandoned underground quarries in Oya town of Utsunomiya City. The authors investigated damaged areas soon after the earthquake and they present their investigation results. They also discuss their implications in short and long-term performance of abandoned mines and quarries possible counter-measures against collapses in this article.