1. 1) Agatsuma, K. Tobita, Y. Sera, R. Hironaka, Y. Amari, N. and Konno, C. (2014): Characteristics of subsurface cavities in Miyagi pref. caused by the Great East Japan Earthquake -incidence rate trend analysis -. The Japanese Geotechnical Society special symposium - overcome the Great East Japan Earthquake -. pp. 285-293 (in Japanese).
2. 2) Okamoto, J. Matsuguma, T. and Hamasaki T. (2017): Utilization of subsurface cavity survey technology for early road restoration after earthquake disaster, Japan Society of Civil Engineers 2017 Annual Meeting, Ⅲ-478 (in Japanese).
3. 3) Sato, M. Tokunaga, T. Saika, M. Syoji, H. and Nisimura, T. (2019): Characteristics of subsurface cavity and a proposal of sinkhole prevention method after 2018 Hokkaido Eastern Iburi Earthquake, Japan Society of Civil Engineers 2019 Annual Meeting, CS12-32 (in Japanese).
4. 4) Sera, R. Koike, Y. Kuwano, R. and Kuwano, J. (2014): Subsurface cavities in the liquefied ground caused by the Great East Japan Earthquake, Japanese Geotechnical Journal, Vol. 9 No.3, pp. 323-339 (in Japanese).
5. 5) Tokunaga, T. Sato, M. Syoji, H. and Okuda, M. (2020): Consideration of sinkhole prevention method after large-scale earthquakes - from the case of 2018 Hokkaido Eastern Iburi Earthquake -, Japan Society of Civil Engineers 2020 Annual Meeting, CS10-31 (in Japanese).