1. Petroleum and Marine Resources Division; Korea Institute of Geoscience and Mineral Resources; 92 Gwahang-no, Yuseong-gu, Daejeon 305-350 South Korea
2. School of Civil and Environmental Engineering; Georgia Institute of Technology; 790 Atlantic Drive, Atlanta Georgia 30332-0355 USA
3. U.S. Geological Survey; 384 Woods Hole Road, Woods Hole Massachusetts 02543 USA