选取易县地震台YRY-4型分量式钻孔应变仪2012—2020年观测数据,进行Venedikov调和分析,并对2015—2020年四分量数据S1、S2、S3、S4进行自洽检验,发现应变观测数据连续性、可靠性较高。选取该台2018—2019年钻孔应变原始数据S1、S2、S3、S4,利用面应变S1 + S3、S2 + S4相关系数,分析河北省3次ML≥4.0地震前数据异常变化,并利用剪应变S1 - S3、S2 - S4的大小,分析受抽水干扰的NE分量主应力方位角,判断干扰源方位,结果发现:①面应变与剪应变在地震发生前均会出现异常变化,且剪应变异常变化幅度较大,应与震中相对于观测井的位置有关;②对于受抽水干扰的钻孔应变NE分量,利用剪应变固体潮数据推算主应力方位角,可得干扰源在钻孔应变观测室NW80.96°方位,与实际位置存在一定偏差。
This study selects the observation data of YRY-4 component borehole strainmeter at Yixian Seismic Station from 2012 to 2020 to carry out a Venedikov adjustment and analysis and conduct a self-consistent test for the 2015 to 2020 YRY-4 component data S1, S2, S3, S4, and find that the continuity and reliability of strain observation data are high. The original data of S1, S2, S3, S4, of the borehole strainmeter observations from 2018 to 2019 are selected to analyze the abnormal changes before 3 ML≥ 4.0 earthquakes in Hebei Province by using the correlation coefficients of the face strains S1 + S3 and S2 + S4 and analyze the pumping interference influence of the NE component of the main stress by using shear strain S1 - S3 and S2 - S4 to determine the location of the interference source. The results found: ① Both face strain and shear strain show abnormal changes before earthquakes and the variation amplitude of shear strain is larger. It should be related to the position of observation well relative to the epicenter; ② For the NE component of the borehole strain disturbed by pumping, the interference source can be obtained in the direction of NW80.96°relative to the strain observation room using the principal stress azimuth calculated from the shear strain solid tide data. This result has a certain deviation from the actual position.
2021,42(4): 119-126 收稿日期:2021-01-08
DOI:10.3969/j.issn.1003-3246.2021.04.015
基金项目:中国地震局监测、预报、研究三结合课题:河北易县地应变受不同环境干扰的定量特征分析(项目编号:3JH-201901035)
作者简介:龚燕民(1982-),男,工程师,主要从事数字形变学科相关分析与研究工作
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