U. S.-Korea Cooperative Research on Acoustic Properties of Fine-Grained Gas-Bearing Sediments Offshore SE Korea

9816277威尔金斯该奖项提供资金，允许罗伊H。2008年12月26日，秘书长与夏威夷大学夏威夷地球物理研究所的Wilkens先生合作，与韩国忠南国立大学海洋学系的Soo-Chul Park博士一道开展一项为期24个月的合作研究方案，研究朝鲜半岛东南沿海细粒含气沉积物的声学特性。 海底沉积物中气泡引起的声学浑浊在世界范围内是一种常见现象，但人们对它的认识还很有限。 即使沉积物中微量的气体并不表现出声学混浊，也能使纵波速度减慢到影响双向地震传播时间到深度的转换的程度，在沉积物-海水系统中，海底上部10米的物理和声学特性梯度最大。 在该区域内，孔隙率可能变化20-30%（1.0至0.7），密度可能变化50%（1.02-1.50 gm/cc）。 压缩波速度通常变化很小，保持接近水的速度，使得声阻抗变化和反射器位置由这10米层内的密度分布中的拐点决定。 这一一般规则的一个例外是当气体存在于沉积物孔隙流体中。 PI测量了波罗的海含气沉积物中的声速，而他的韩国合作者正在沿着朝鲜半岛东南海岸进行此类研究。 目前的合同将允许PI访问韩国，进行联合规划和随后的合作研究，乘坐韩国研究船，详细调查这一近海底含气沉积物区上方和内部的各种性质的行为。 两个合作者的科学计划预计将大大受益于测量技术的结合和两个研究小组的专业知识的融合。 该项目与美国的目标有关-韩国合作科学计划，旨在通过科学信息，思想，技能和技术的交流以及通过互利问题的合作来提高美国和韩国科学家和工程师之间的合作水平。 韩国的参与得到了韩国科学和工程基金会的支持。

9816277WilkensThis award provides funds to permit Dr. Roy H. Wilkens, Hawaii Institute of Geophysics, University of Hawaii, to pursue with Dr. Soo-Chul Park, Department of Oceanography, Chungnam National University, Korea, for 24 months, a program of cooperative research on acoustic properties of fine-grained gas-bearing sediments off the southeast coast of the Korean peninsula. Acoustic turbidity caused by gas bubbles in seafloor sediments is a common occurrence worldwide, but it is as yet poorly understood. Even minute traces of gas in sediments that do not exhibit acoustic turbidity can slow compressional wave velocity to such an extent as to influence the conversion of two-way seismic travel time to depth.The upper 10 meters of the seafloor contain the largest gradients in physical and acoustic properties in the sediment-seawater system. Within this zone porosity may change by 20-30% (1.0 to 0.7) and density may vary by 50% (1.02-1.50 gm/cc). Compressional wave velocities usually change very little, remaining close to that of water, so that acoustic impedance changes and reflector positions are dictated by inflections in the density profile within this 10 meter layer. One exception to this general rule is when gas is present in sediment pore fluids. The PI has made measurements on the velocity of sound in gas-bearing sediment in the Baltic Sea, while his Korean collaborator is conducting such studies along the southeast coast of the Korean Peninsula. The present award will allow the PI to visit Korea for joint planning and subsequent cooperative research, aboard Korean research vessels, to investigate in great detail the behavior of various properties above and within this near seafloor gassy sediment zone. The scientific programs of both collaborators are expected to benefit greatly from the combination of measuring techniques and blending of expertise of the two research groups. This project is relevant to the objectives of the U.S.-Korea Cooperative Science Program which seeks to increase the level of cooperation between U.S. and Korean scientists and engineers through the exchange of scientific information, ideas, skills, and techniques and through collaboration on problems of mutual benefit. Korean participation is supported by the Korea Science and Engineering Foundation (KOSEF).***