A Review of the Calculation Formula for the Four-component Borehole Strainmeter and Application to Earthquake Cases

作     者：SU Kaizhi 

作者机构：Institute of Crustal DynamicsChina Earthquake Administration 

出 版 物：《Earthquake Research in China》 (中国地震研究（英文版）)

年 卷 期：2019年第33卷第1期

页      面：132-146页

核心收录：

学科分类：07[理学] 

基　　金：sponsored by the Central Level Scientific Research Institutes of Basic R&D Special Fund Business of the Institute of Crustal Dynamics CEA(ZDJ2017-25) 

主　　题：Four-component borehole strainmeter Ludian MS6. 5 earthquake Yiliang MS5. 7 earthquake Plane strain abnormality Shear strain abnormality Self-test of data Strain anomaly 

摘      要：Based on the principle formula for the four-component strainmeters, we can directly obtain the specific plane strain, shear strain and azimuthal angle of the principal strain, and the maximum and minimum principal strains calculated afterwards are the indirect result. The problems of practicality of the sensitivity coefficients A and B of plane strain and shear strain are then discussed. Based on this idea, we analyzed the observation data of several four-component borehole strainmeters near the epicenter of the Yiliang M_S5.7 earthquake in 2012 and the Ludian M_S6.5 earthquake in 2014 in the Zhaotong area, Yunnan Province. The results show that the analysis based on the perspective of plane strain and shear strain has an obviously better effect than that based on the component readings, and can directly peel off the respective abnormality of the plane strain and shear strain. In addition, the correlation coefficient curves between measured data of two plane strains show significant anomalies which often occur several days before and during the earthquake.