1. Earthquake Disaster Prevention Research Center, Public Works Research Institute, Ministry of Construction, 1, Asahi, Tsukuba-shi, Ibaraki, 305, Japan, Telephone: 81/298-64-2933, E-mail: matsuo@pwri.go.jp; T. Tsutsumi, Research Engineer, Soil Dynamics Division, Telephone: 81/298-64-4969,
2. Earthquake Disaster Prevention Research Center, Public Works Research Institute, Ministry of Construction, 1, Asahi, Tsukuba-shi, Ibaraki, 305, Japan, Telephone: 81/298-64-2829,
3. Earthquake Disaster Prevention Research Center, Public Works Research Institute, Ministry of Construction, 1, Asahi, Tsukuba-shi, Ibaraki, 305, Japan, Telephone: 81/298-64-4969,, Telefax: 81/298-64-2576