木兰山重力基线场的初值测定及重力变化分析  

DETERMINATION OF GRAVITY VALUES FOR MULANSHAN CALIBRATION BASELINE AND ANALYSIS OF GRAVITY CHANGE

作　　者：汪健 张新林[2,3] 谈洪波[2,3] 胡敏章 吴桂桔[2,3] 李忠亚 张明辉[2,3] WANG Jian;ZHANG Xin-lin;TAN Hong-bo;HU Min-zhang;WU Gui-ju;LI Zhong-ya;ZHANG Ming-hui(College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Key Library of Earthquake Geodesy,Institute of Seismology,China Earthquake Administration,Wuhan 430071,China;Hubei Earthquake Agency,Wuhan 430071,China)

机构地区：[1]中国科学院大学,地球与行星科学学院,北京100049 [2]中国地震局地震研究所,地震大地测量重点实验室,武汉430071 [3]湖北省地震局,武汉430071

出　　处：《地震地质》2023年第2期553-569,共17页Seismology and Geology

基　　金：国家自然科学基金(41604014,41974021,41774015,42074172);中国地震局地震科技星火计划项目(XH20039,XH21021)共同资助。

摘　　要：文中基于绝对重力控制下的木兰山基线场2018年和2022年的重力观测资料,研究了一次项系数在不同读数段的分布规律、木兰山基线场的重力场分布和近期重力变化特征。结果表明:相对重力仪不同读数段的一次项系数存在差异,武汉—宜昌测段(子测段)的一次项系数与武汉—绿葱坡测段(总测段)的差异可达4.809‰, CG-6型与CG-5型重力仪的结果较为一致,2类重力仪间无系统偏差;总测段的一次项系数是各子测段一次项系数的加权平均结果,其相应的权因子为子测段与总测段的重力段差比值;木兰山基线场的最大重力段差(G01—G03)为102.176mGal,各测点的重力值平均精度为4.8μGal;2018—2022年木兰山基线场测点的重力变化区间为5.9~12.8μGal,重力场整体呈正变化,测段重力变化区间为-4.8~6.9μGal。测点周边环境变化、地表垂直运动、地表水储量变化对地表实测重力变化均产生了一定影响。综合上述各项改正后的测点和测段重力变化均值较实测值相应减小了38.2%和50.8%,改正后的重力变化结果更为精准,但其不确定度相应增加了2.5%和2.8%。综合分析测点和测段的重力场动态变化可有效提取异常信息,为地震重力监测提供更精确的数据支持。Using the gravity observation data of Mulanshan short gravity baseline field in 2018 and 2022,we established a high-precision short gravity baseline field of Mulanshan based on the relative gravity joint measurement method under the control of absolute gravity.We also analyzed and discussed the accurate calibration of the monomial coefficient of the relative gravimeter during the construction of the gravity short baseline field,the distribution of gravity values in the gravity baseline field of Mulanshan and the contribution of various environmental factors in the gravity variation results,these results show that:(1)Maximum gravity segment difference of Mulanshan calibration baseline is 102.176mGal from G01 to G03 stations,and the average accuracy of gravity value of each measuring station reaches 4.8μGal.The geological structure of the Mulanshan baseline is stable,and the gravity change of measuring stations is not obvious.From 2018 to 2022,the gravity variation range of measuring stations was 5.9~12.8μGal,with an average of 9.5μGal,and the average uncertainty was±5.7μGal.The gravity field mainly showed a positive change.The variation range of gravity in each measurement section is-4.8~6.9μGal,with an average of(1.8±8.6)μGal.The change of the surrounding environment has a certain impact on the gravity field,and the contribution of the new buildings near the G01 and G02 to the gravity change is 3.6μGal and-0.51μGal,respectively.These gravity changes of measuring stations in the IOS and Mulanshan baseline caused by vertical surface movement are(2.17±0.44)μGal and(1.67±0.45)μGal.The gravity effect caused by the change of surface water storage is(1.07±0.84)μGal,which cannot be ignored.Compared with observation results,the gravity change of each measuring station and section after correction is reduced,and the average gravity change values are reduced by 38.2%and 50.8%,respectively.The corrected gravity change results are more accurate.Due to the cumulative effect of errors in the correction process,t

关 键 词：木兰山基线场 重力变化 一次项系数 地表重力观测 

分 类 号：P315.72[天文地球—地震学]