【摘要】 详细计算和分析了云南省几个地区的五次ML 6 5级强震前的应变面积。结果表明 ,在震前 5～ 8年的时间内 ,归一化为 4级地震的St 值会出现明显异常变化。St 值空间分布表现为二种特征 :(1)未来震中区域St 值变小 ,周围地区增大 ,形成空区。 (2 )St 值有由零星分布逐渐向震中区收缩、集中、增强的趋势。此外 ,从St 值空间动态变化图像的演变规律得出结论 ,强震前 5～ 8年中小地震活动是由时间稍长的平稳、随机分布到时间较短的增强、集中分布再到时间更短的平静阶段所组成的非线性变化过程。更多还原

【Abstract】 The strain areas of several regions in Yunnan before the 5 strong earthquakes with ML≥6 5 are calculated and analyzed in detail. The results show that obvious variations in anomalies for St values with normalized magnitudes of M4 appeared within 5 to 8 years before the earthquakes and space distribution of the St values has the two characteristics; 1. The St values in future epicentral region decreased and the St values in the region around the epicenter increase, forming gap and 2. the St values have tendency to gradually concentrate and increase to epicentral region from scatted distribution. And also, from the evolution law of space dynamic variation pattern of St values, it can be drawn that the middle and small seismicity 5 to 8 years before the strong earthquakes shows a nonlinear evolution process consisting of smooth random distribution in relatively long period to concentrative distribution in short period and to shorter quiet period.更多还原