云南流动重力测网数据质量及场源分辨能力评估  

Evaluation of data quality and field-source resolution of terrestrial mobile gravity network in Yunnan

作　　者：郑秋月 刘东 杨薪俊 黄江培 王青华[1] 陈石[2,3] ZHENG Qiuyue;LIU Dong;YANG Xinjun;HUANG Jiangpei;WANG Qinghua;CHEN Shi(Yunnan Earthquake Agency,Kunming 650041,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Beijing Baijiatuan Earth Science National Observation and Research Station,Beijing 100095,China)

机构地区：[1]云南省地震局,云南昆明650041 [2]中国地震局地球物理研究所,北京100081 [3]北京白家疃地球科学国家野外观测科学研究站,北京100095

出　　处：《华中科技大学学报（自然科学版）》2022年第9期48-55,共8页Journal of Huazhong University of Science and Technology(Natural Science Edition)

基　　金：中国地震局震情跟踪青年课题资助项目(2021010207,2022010202);云南省地震局科研项目(2021YBZX06)。

摘　　要：首先对云南流动重力测网2018~2020年陆地时变重力数据进行精细化处理,基于测期准同步的绝对重力数据,引入贝叶斯重力平差方法对多台CG-5型相对重力仪的格值系数进行优化估计,同时获取了多台仪器的非线性漂移特征;其次,利用重力段差、段差残差及互差相关性分析来评估数据质量,开展绝对重力交叉检验,量化了仪器漂移率变化及格值系数不准引起的误差;最后,在设定场源异常体参数情况下,采用球面六面体单元构建不同分辨率的重力异常扰动模型进行检测板测试,并通过等效源反演方法对场源体进行恢复,进而评估了测网的场源分辨能力.结果表明:贝叶斯平差方法能有效降低CG-5型相对重力仪的非线性漂移及格值系数偏差带来的不确定性,进而提高平差数据精度;测网在主要块体边界带及断裂附近的场源分辨能力以0.50°×0.50°为主,而在测点密集的小江断裂带、红河断裂带北段等区域,其场源分辨能力达0.25°×0.25°.研究结果能提供高精度的陆地时变重力数据,优化测网布局,且有助于更好地研究地震重力监测、地壳垂直运动、地下水变化和地球内部物质运移等地球物理学问题.In this study,the time-varying microgravity data from 2018 to 2020 of the survey network in Yunnan was analyzed firstly,and based on the quasi-synchronous absolute gravity(AG)data,the Bayesian gravity adjustment method was introduced to optimize the scale factor of the CG-5 relative gravimeters,then the nonlinear drift characteristics of the different instruments were obtained.Additionally,the data quality was evaluated by analyzing the gravity difference(GD),residual of GD,and mutual difference of GD,and the AG cross-validation was carried out to quantify the errors caused by the inaccurate scale factor and instrumental drift rate variations.Moreover,in order to determine the field-source resolution of the time-varying gravity monitoring network in Yunnan,the Tesseroid grid model was used to construct the gravity anomaly disturbance checkboard model with different resolutions under the condition of setting field-source anomaly body parameters,and the gravity field modeling experiment was carried out.The results show that Bayesian adjustment method can reduce the uncertainty caused by the deviation of nonlinear drift rate and the scale factor of CG-5 relative gravimeter effectively,and improve the accuracy of adjustment gravity data.The field source resolution of the network is mainly 0.50°×0.50°in the boundary zone of the main block and near the main faults,while the field source resolution of the network is 0.25°×0.25°in Xiaojiang Fault zone and the northern segment of the Red River fault zone where the measurement points are highly concentrated.The results of this study can provide terrestrial time-varying microgravity data with high-precision,and optimize the layout of the survey network,which are helpful to carry out geophysical problems such as seismic gravity monitoring,vertical crustal movement,groundwater changes and material migration in the earth.

关 键 词：时变微重力 贝叶斯重力平差 非线性漂移 格值系数 场源分辨能力 球面六面体 

分 类 号：P312[天文地球—固体地球物理学] P223[天文地球—地球物理学]