2014年景谷MS6.6和2018年墨江MS5.9地震前视应力、视体积异常特征研究

Characterization of Apparent Stress and Apparent Volume before the 2014 Jinggu MS6.6 and 2018 Mojiang MS5.9 Earthquake,Yunnan

岩石力学性质实验显示,岩石破坏前会出现扩容现象,可用累积视体积的变化来度量岩体体积的变化。结合岩石破坏前应力-应变关系,通过对滇西南块体震源参数的计算,探讨2014年景谷MS6.6和2018年墨江MS5.9地震前后,震源区及邻区视应力、视体积的变化特征。结果表明:该区的地震视应力与震级、地震矩的皮尔逊相关系数r分别为0.73,0.58,视应力与震级的相关性较大,与地震矩存在正相关关系;景谷MS6.6地震前8.4个月和墨江MS5.9地震前4.2个月,视应力和归准化视应力均出现高值异常,累积视体积增长,且增长速率增大。景谷地震前其震源区、墨江地震前震源区同一断裂带南段为视应力高值区域。

According to the experiment of rock mechanical properties,before rock failure,volume expansion phenomenon is expected to occur.We use the change of cumulative apparent volume to measure the change of rock volume.Combining stress-strain relationship before failure of rock,based on the calculation of the focal parameters of the southwest Yunnan block,we examined the temporal evolution of apparent stress,apparent volume,the characteristics of other source parameters,and spatial apparent stress before the 2014 Jinggu MS6.6 earthquake and the 2018 Mojiang MS5.9 earthquake.The results show that the Pearson correlation coefficients of apparent stress with magnitude,moment are 0.73,0.58,respectively.The apparent stress is highly correlated with the magnitude and has a positive correlation with the moment.In the 8.4 months before the 2014 Jinggu MS 6.6 earthquake and 4.2 months before the 2018 Mojiang MS 5.9 earthquake,the apparent stress and normalized apparent stress were abnormal with a high value,and the cumulative apparent volume increased at a large rate.The focal area before Jinggu earthquake and the southern segment of the seismogenic fault zone before the Mojiang earthquake are the location of a higher apparent stress.