单层/双层地壳物理参数对重力数据反演海底地形影响分析  

Analyzing the influence of physical parameters of single layer/double layer crust on seafloor topography inversion from gravity data

作　　者：范雕 李姗姗[1] 孟书宇 单建晨 黄炎 王傲明 刘鑫宇 FAN Diao;LI ShanShan;MENG ShuYu;SHAN JianChen;HUANG Yan;WANG AoMing;LIU XinYu(Information Engineering University,Zhengzhou 450001,China;32022 Troops,Guangzhou 510630,China;31201 Troops,Guangzhou 510630,China)

机构地区：[1]信息工程大学,郑州450001 [2]32022部队,广州5106303 [3]31201部队,广州510630

出　　处：《地球物理学进展》2022年第6期2258-2266,共9页Progress in Geophysics

基　　金：国家自然科学基金项目(42204009,42174007,42174008,41774018,42074017);军队“双重”建设项目(2021ky030)联合资助。

摘　　要：针对利用海面重力数据构建海底地形模型质量受诸多地壳地球物理参数影响现状,以重力异常反演海底地形的频率域算法模型为基础,讨论了不同地球物理参数对单层/双层地壳仿真结构和不同均衡补偿模式下导纳函数各频段影响程度,推导给出了不同地球物理参数及其组合对海底地形反演结果影响的定量数学表达.仿真试验结果表明,单层地壳的密度变化导致单层导纳函数和双层导纳函数明显分离;双层地壳仿真结构中海山载荷密度对导纳函数影响显著且几乎为全频段影响;因此,建议应用解析法开展数值试验分析时,重点考虑海山载荷密度(双层地壳)或者地壳密度(单层地壳)变化.就当前海底地形反演精度而言,运用相关解析算法建立海底地形数值模型时,应重点关注有效弹性厚度、平均海深、海山和海水密度差异参数取值准确性,特别是顾及地壳均衡补偿恢复海底地形,岩石圈有效弹性厚度(通过有效弹性厚度可获取挠曲刚度)取值准确程度将较大程度影响最终海底地形模型效能高低.In view of the fact that the quality of seafloor topography model constructed by sea surface gravity data is affected by many crustal geophysical parameters,we discussed the influence of different geophysical parameters on different frequency band of admittance function under single/double crustal model and different isostatic compensation,and deduced the mathematical expression of the influence of different geophysical parameters and their combination on seafloor topography inversion based on the frequency domain inversion algorithm.The simulation results showed that the change of single-layer crustal density led to the obvious separation of single-layer admittance function and double-layer admittance function;the influence of the density of seamount load in double-layer crust on admittance function was significant and almost in full frequency range.Therefore,it is suggested that we should focus on the change of seamount load density(double crust)and crustal density(single-layer)when using analytic method to carry out numerical analysis.As far as the accuracy of current seafloor topography inversion is concerned,when using the analytic method to establish the seafloor topography model,we should pay attention to the accuracy of the parameters such as effective elastic thickness,average sea depth,the density difference between seamount and sea water.Especially the accuracy of the effective elastic thickness(flexural stiffness can be obtained through the effective elastic thickness)will greatly affect the effectiveness of the final seafloor topography model when considering the crustal isostatic compensation to inverse the seafloor topography.

关 键 词：重力异常 海底地形 单层地壳模型 双层地壳模型 地球物理参数 

分 类 号：P223[天文地球—大地测量学与测量工程]