1. Department of Earth
System Science and Technology, Kyushu University Kasuga Park, Kasuga, Fukuoka, 816-8580,
Japan
2. Research Institute
for Applied Mechanics, Kyushu University Kasuga Park, Kasuga, Fukuoka, 816-8580,
Japan
3. Division of
Environmental, Civil and Transportation
Engineering, Ajou University Woncheon-dong,Yeongtong-gu, Suwon, 443-749, South Korea