云南强震前地震活动因子A值异常动态演变特征

运用地震活动因子A值参数全面、深入地研究了云南强震前尤其是强震活跃期首发强震前地震活动在时间、空间的动态演变过程,研究结果显示:(1)强震前1～2年,在未来震中周围A值出现显著高值变化,异常阀值为A≥0.6;(2)强震前3～4年,A≥0.6的高值异常区主要分布在云南省外围或边界附近,省内A值异常较少。随着强震的临近,A值异常面积逐渐增大,并且向省内、未来震中迁移,震前1年或1～2年云南地区A值异常单位面积和省内外异常单位面积的比值出现明显转折回升。

Dynamic Evolution Characteristics of Seismicity Factor A-value Abnormity before Strong Earthquakes in Yunnan

We studied the temporal and spatial dynamic evolution of seismicity factor A-value before strong earthquakes,especially before the first shock in the active period of strong earthquakes in Yunnan.The results show as follows:(1) A-value would appear evident high value near future epicenters during 1 ～ 2 years before strong earthquakes,abnormal value is A≥0.6.(2) The high value anomalous areas of A≥0.6 mainly distributed in the surrounding areas or the boundary areas of Yunnan Province,but rarely distributed in the inner of Yunnan Province during 3 ～ 4 years before strong earthquakes.With the approach of the strong earthquakes occurred,the areas in which A-value was abnormal expanded gradually and moved toward the future epicenters or the inner of Yunnan Province.During one year or 1 ～ 2 years before strong earthquakes,the unit area in which A-value was abnormal in Yunnan and the ratio of the unit area in which A-value was abnormal between inside and outside of Yunnan significantly turned and picked up.