1999年河源2次4～5级地震的中短期前兆异常及其思考

Analysis and thought to the Mid-short period precursor anomalies of two M_L4～5 earthquakes occurring in Heyuan in 1999

对1999年广东省河源市两次4～5级地震前出现的前兆异常进行分析后认为,这些异常既反映了河源两次地震前局部应力场的变化,也反映了华南构造块体应力场的增强,是台湾集集7 6级强震群前大范围内地壳活动增强的表现。由于前兆异常的空间分布与块体内深大活动断裂构造的局部应力集中有关,因此,由前兆异常的多少和分布来判断未来强震的发生地点将是困难的。

After analyzing precursor anomalies before two XML4～5 earthquakes having occurred in Heyuan in 1999, we thought that these anomalies reflected local stress field variations, also the strength of tectonic block stress field of South China. And showed the strength of crustal movement in large field before Jiji M76 strong earthquake swarm. Because the spatial distribution of precursor anomalies related with local concentration of stress on the large active faults of tectonic block, it is difficult to forecast the place of future earthquake according the amount and spatial distribution of precursor anomalies.