基于随机聚集维数分析地震对乡村聚落分布演变的影响——以云南丽江、武定和鲁甸为例

Analysis of the Influence of the Earthquake on the Evolution of the Rural Settlements Based on the Random Aggregation Dimension:A Case Study of Lijiang,Wuding,and Ludian in Yunnan

为研究地震前后乡村聚落演变特征的变化对乡村聚落选址的安全意义,以云南1995年武定6.5级、1996年丽江7.0级、2014年鲁甸6.5级地震极震区乡村聚落的分布特征为研究对象,使用分形理论随机聚集维数分别测算出3次地震极震区内乡村聚落在地震前1年以及地震后第3年的分维数。结果表明:(1)地震后极震区内乡村聚落数量明显增多,聚落分布更为分散;但2014年鲁甸6.5级地震极震区乡村聚落数的增长幅度明显低于前两地,这归因于2006年以来云南省对乡村民房的抗震加固措施。(2)地震后极震区乡村聚落的分布格局发生了明显变化,乡村聚落围绕震中分布变得更为离散,震后乡村聚落往往会向未受震灾影响或影响轻微的区域迁移。

The evolution of rural settlements before and after earthquakes is of great significance to the selection of the site of the rural settlements.In this paper,we studied the distribution characteristics of the rural settlements in the meizoseismal areas of the 1995 Wuding M_(S)6.5 earthquake,the 1996 Lijiang M_(S)7.0 earthquake,and the 2014 Ludian M_(S)6.5 earthquake in Yunnan Province.We respectively calculated the fractal dimensions of these rural settlements one year before and three years after the earthquakes.The results show:(1)Due to the implement of measure of the seismic reinforcement of rural houses in Yunnan Province,the rural settlements in meizoseismal areas increased significantly after the earthquakes,and became more dispersed.The rural settlements in Ludian increased more slowly than the ones in the other two regions.(2)The distribution pattern of rural settlements changed obviously after the earthquake.The rural settlements in the meizoseismal areas of the three earthquakes were more scattered after the earthquakes.The rural settlements tended to move to the sites unaffected or slightly affected by earthquakes.