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本文根据一些地震前后地磁场出现上下波动形态的震磁效应现象,以包体模式为基础,提出了该类震磁效应的可能的物理机制。当包体处于临界失稳状态时,由于大量微裂隙的产生,使孔隙压力下降,岩石有效应力增加,导致包体硬化致稳;若周围有流体渗入包体,则将导致孔隙压力回升,有效应力下降,包体将再度失稳,然后又是致稳,直至最后由于包体动态失稳而发生地震。根据流体扩散磁效应理论,这个过程将引起上下波动型的震磁变化。最后讨论了各种条件下该类震磁效应的可能形态,并指出这种韵律性的前兆现象可能有一定的普遍性,是短临地震预报中值得重视的一个现象。
According to the phenomenon of up-and-down fluctuation of geomagnetic field before and after some earthquakes, this paper proposes the possible physical mechanism of this type of seismic effect based on the inclusion mode. When the inclusions are in the critical instability state, the pore pressure drops and the rock effective stress increases due to a large number of micro-fractures, resulting in hardening of the inclusions. If the surrounding fluid infiltrates the inclusions, the pore pressure will rise and become effective When the stress drops, the inclusions will again destabilize and then stabilize again until the earthquake finally occurs due to the dynamic instability of the inclusions. According to the theory of fluid diffusion magnetic effect, this process will cause up-down fluctuation of the seismic magnetic changes. At last, the possible forms of this kind of magnetotactic effect under various conditions are discussed. It is pointed out that this kind of rhythmic precursor phenomenon may have certain universality and it is a phenomenon worthy of attention in short-term and short-term earthquake prediction.