微破裂对岩石剩磁的影响——对地震预报的意义

本实验对岩石破裂过程中的磁性变化进行了研究,证实岩石剩余磁化强度随施加的应力而变化,并首次发现剩磁的变化具有低压时与原有微裂隙的闭合以及高压时与新裂隙的生成有关的特点,在岩样临近破裂的状态下这种现象尤为明显.因此,在研究地震的地磁前兆时,应注意孕震区介质微观上的完整性及应力-应变关系,并注重观测与前震相关的地磁场变化.

THE EFFECT OF CRACKING ON REMANENT MAGNETIZATION OF ROCKS——IT'S IMPLICATION TO EARTHQUAKE PREDICTION

In this study, the changes of remanent magnetization in rocks during cracking process are investigated and its nature is found for the first time to be related with closing of existed micro-cracks at lower applied pressure and opening of newly-developing microcracks at higher pressure, respectively. The later is rather obvious prior to the failure of rock samples. These phenomena imply that the compactness and stress-strain relation of medium in the seismogenic zone should be noticed and the variation of local geomagnetic field connected with fore-shocks should be searched in the study on geomagnetic precursors.