中文摘要：

采用标度变换法，对云南省西北部地区地震活动空间分布的关联维进行了计算，得到了云南西北部不同时段的地震活动空间分布关联维的等值线图．讨论了强震发生前后震中地区关联维演变过程和空间分布特征随时间变化，结果显示，M≥6．0强震发生前存在不同形式的降维过程．

英文摘要：

The correlation dimension of space distribution of seismic activity in northwest ot Yunnan is calculated by means of scale transformation. The contour map of spatial correlation dimension distribution at different periods in northwest of Yunnan are obtained. The evolving process of correlation dimension and the characteristics of space distribution variation with time before and after strong earthquakes are discussed. The results showed that there is a phenomenon of fractal dimension dropping before the occurring of M ≥ 6.0 earthquakes.