东沙群岛西南泥火山区Chirp浅剖数据的海底物性反演

Chirp浅剖图像可以显示东沙群岛西南海域存在泥火山.通过基于Chirp浅剖记录数据的反演方法研究，定量地分析泥火山区海底物性参数.首先由Chirp浅剖记录的反射振幅计算了海底反射系数，结果表明泥火山区的反射变化很大(0.1~0.8).对于海底弱反射(＜0.45) 区域，用Schock-Stoll模型以及物理参数间的经验公式反演海底浅表层物理性质参数(速度、密度、孔隙度等参数)；对于海底强反射(＞0.45) 区域，用Gardner经验公式反演海底浅表层物理性质参数.反演结果表明研究区海底物性变化大，声速最高达5 237 m/s，密度最大为2.673 g/cm3.反演的物性参数与实验室测量值吻合度较高.Chirp浅剖数据反演是一种有效可行的遥测海底声学参数方法. 

Inversion of the Physical Properties of the Seabed Using Chirp Sub-Bottom Data in Mud Volcanoes Field of the Southwest of Dongsha Islands

Mud volcanoes are imaged from Chirp sub-bottom profiles across the southwest of Dongsha Islands. In order to quantify the physical properties of the seabed, this paper studies the inversion of the Chirp sub-bottom data. First, reflection coefficients of the seabed are calculated, the results show that the reflection magnitudes of the seabed vary from 0.1-0.8. The physical properties (velocity, density, porosity etc.) of the seabed are obtained by the Schock-Stoll Model and the empirical relationships among the physical properties for the part reflection coefficients smaller than 0.45, and the physical properties (velocity and density) of the seabed are obtained by Gardner empirical equation for the part reflection coefficients larger than 0.45. Results of the inversion show that the physical properties vary greatly with the maximum velocity of 5 237 m/s and density of 2.673 g/cm3. The Chirp data-based physical properties highly coincide with the laboratory measurements for sampled sediments, thus provides us a remote acoustic method for estimating the physical properties of the seabed.