【摘要】 应用分形理论与方法，计算了唐山、海城、澜沧－耿马地震前小震活动能量分布的信息维及其在空间上的差异和时间上的变化，结果表明：（１）局域空间分数维可以反映大震前小震活动能量分布的空间变化特征，大震发生在信息维中等值区；（２）局域时间分数维显示大震前小震活动存在降维过程，且大震发生在降维之后的升维过程中或发生在降维过程结束之时更多还原

【Abstract】 The local information dimensions of seismic energy distribution before Tangshan, Haicheng and Lancang-Gengma earthquakes are calculated by using box-counting. The results show that: (1)the local information dimensions reflect the features of the spatial variation of seismic energy distribution before strong earthquakes that often occur in medium value area.(2)the information dimensions by stages present that the decreasing dimension processes exist in seismic activities before strong earthquake, but they are different as region, time and criterion. Strong earthquakes often occur in rising dimension process after the decreasing dimension process or at closing the decreasing dimension process.更多还原