CG-5重力仪一次项系数变化特性分析及其对观测数据的影响研究

Study on the Change of Primary Term Coefficient of CG-5 Gravimeter and Its Effect on Earthquake Monitoring Data

采用线性回归方法分析2015—2018年云南区域内相对重力观测数据,分析获取到的云南省2台CG-5相对重力仪3年内一次项系数变化差异,发现段差与互差呈线性关系;利用线性回归方法获取3年内每个观测周期的一次项系数,结合绝对重力点资料,对得出的一次项系数进行验证;对比一次项系数修正前后3年期的变化趋势,分析重力变化与2018年地震相关性。结果表明:2台CG-5重力仪一次项系数在3年内均发生变化,且变化规律不一致,一次项系数变化差异最大达到0.0002;在一个观测周期内,一次项系数随时间及测值段均未发生明显变化;一次项系数修正前后对重力观测数据最大影响能达到100×10^-8m/s^2以上,且修正后的数据与绝对重力观测值符合性更好,与地震的相关性也更加明显。

Based on the relative gravity observation data from 2015 to 2018 in Yunnan,we studied the relationship between segment difference and mutual difference of two CG-5 gravimeters belong to the Yunnan earthquake administration,and calculated the primary term coefficient differences between two gravimeters by linear regression method in three years. Then,we analyzed the differences of primary term coefficient in different time periods and different measurement periods in an observation period. The results show that the first? order’s coefficients of the two gravimeters have changed in three years,and have different change laws. The max-difference has reached 0. 000 2,while the primary term coefficient has not changed significantly with time or with the measured interval in a period of observation. We calculated the primary term coefficient of each observation period in three years,and proved the results are reasonable and applicable,combined with the data of absolute gravity. We analyzed the correlation between gravity change and 2018 earthquake by comparing the trend maps of three years before and after primary term coefficient corrected. It is concluded that the maximum effect on gravity observation data can reach 100 × 10-8 m·s-2 before and after primary term coefficient correction. The corrected data are in good agreement with the absolute gravity observations and the correlation with earthquakes is also more obvious.