1. Chief Researcher, BMC Corporation, WBG Marive West 25th Floor, Nakase 2-6, Mihama-Ku, Chiba 261-7125, Japan (corresponding author)
2. Director, Disaster Prevention Research Laboratory, Research and Development Center, East Japan Railway Company, Nisshin-cho 2-479, Kita-ku, Saitama 331-8513, Japan.