四分量钻孔应变仪计算式梳理及震例应用

从四分量钻孔应变仪基本原理式的分析出发，可知首先得到的物理量是岩石面应变和切应变及主应变的方位角，然后得到的最大、最小主应变是间接结果，建议多使用面应变和切应变的表示方法。由此说明当下需要重视灵敏系数A、B的实用化研究。据此思路，以云南省昭通地区2012年彝良M 5.7地震和2014年鲁甸M 6.5地震为例，对2次震中附近几台四分量钻孔应变仪记录的观测数据进行计算，初步分析表明，基于面应变和切应变的视角进行分析，其效果多优于以元件为单位的分析，可直接得到面应变和切应变异常及特征；2个面应变测量数据间的相关系数曲线，有时会在震前数天和震时出现异常变化，此新线索值得关注。

The four-component borehole strainmeter calculation formula and strain anomalies of two earthquakes

This paper starts with the simplest solution for a four-component strainmeter, directly obtain specific plane strain,shear strain and azimuthal angle of principal strain. It is pointed out that the maximum and minimum principal strains can be calculated afterwards and they are the result of the second stage. Then, the problems in practicality of the sensitivity coefficients A and B of plane strain and shear strain are discussed. Based on this idea, we analyzes the observation data of several four-component instruments near the epicenter of Yiliang M 5.7 earthquake in 2012 and Ludian M 6.5 earthquake in 2014 in Zhaotong area, Yunnan Province. It shows that drawing the figure based on the plane strain and shear strain is better than component readings obviously, which can significantly peel off respective abnormality of the plane strain and the shear strain. In addition, the correlation coefficient curve between measured data of two plane strains show significant anomalies often occur several days before and during the earthquake, which worth paying attention.