Spatial Distribution And Clustering Of Seismicity With Ms>5.0 In Yunnan

Based on the information about the seismicities’s longitude, latitude with Ms>5.0 in Yunnan, from the recorded in 886, we make researches on the spatial distribution feathers and spatial point patterns of the sample cases,using the technique of geographic information system and the research methods of spatial point patterns. Firstly, we focus on the statistical description analysis about the center index and discrete trend indicators of the general spatial distribution, to detect the general distribution characteristics. And then we test the heterogeneity of the distribution intensity using the point pattern recognition methods based on density, and establish distribution intensity fitting models based on the exponential functions of coordinates or distances to fit the realistic distribution of the sample cases, and choose the most appropriate model by comparing the goodness-of-fit of the models.And then we test the aggregation characteristics of the point pattern and analyze the relationship between the dependence and the scale using the point pattern analysis technologies based on the distances of the nearest neighbors. Finally, we detect the two-order effects of cross combination of different classes with different attributes and analyze the dependence feathers between the event distribution of different types by innovatively using the two-order cross effect functions of the point patterns. The conclusions are as follows:(1)And in the aspect of discrete tendency of the distribution, the degree of discrete in east-west direction is greater than the north-south direction,And there is skewness of the two directions, And so it forms a standard deviation ellipse with a clockwise angle of 65.667397 degree apart from the original coordinate axis.(2)The distribution intensity of the seismicity sample cases is heterogeneous significantly and there are functional relationship between the distances and the intensity. The point pattern of the sample cases shows aggregation feathers significantly. And the dependence degree incr-eases first, then decreases, and finally reduces to negative with the scale increasing.(3)Any event combinations of different types with different attributes show dependence significantly and the degree of dependence and dependence scales vary in different combina-tions. And a magnitude of 8.0～8.9 earthquake with 0 to 10 km depth attributes show depende-nce significantly in the whole range.