四川芦山余震序列空间格局分析

以芦山3级以上余震数据为基础,运用GIS等方法对余震空间格局进行了研究。结果表明：1.点格局的最邻近指数为0.72,偏离随机分布,暗示余震分布具有一定聚集性：芦山、宝兴、天全是余震分布的中心区域,占总余震的87%,高震级余震也多发于此;2.距离关联维分析表明,余震在2.5~10.5km、17~22km区间内关联程度显著;32~35.5km、36~40km区间也存在关联特征,该结果与地震烈度区长短半轴、地震破裂面长度较为吻合。研究探索了余震空间点格局,对分析、判断余震特征和灾害预防具有借鉴意义。

Analysis of spatial pattern of Lushan aftershocks sequence

Spatial pattern of Lushan aftershocks was studied aided by GIS techniques, and the aftershock sequence no less than 3 magnitude was used as the data source. The results indicated that the about 87% aftershocks took place in three regions, including Lushan, Baoxing and Tianquan country. What＇ s more, high-magnitude aftershocks also concentrated in the three regions, especially the Lushan country. The nearest point index equal to 0.72 indicated that the aftershocks distributed clustered instead of obeying to a complete normal distribution. The distance correlation dimension also indicated that a muhiscale spatial correlation existed in the ranges of 2.5 to 10.5 kilometers and 17 to 22 kilometers. In the range of 32 to 35.5 kilometers and 36 to 40 kilometers the correlation characteristics also existed. The four ranges show a correlation with the long and short axis of different earthquake intensity zones, which were influenced by the length and extending directions of earthquake rupture surface. The study investigated the spatial pattern of aftershocks, which shows its significance of analysis and estimation on the aftershocks＇ characteristics as well as the hazard prevention.