基于奇异谱分析的汶川地震震前地倾斜数据分析

汶川地震给人们的生命及财产造成了严重的损失,故对汶川地震震前地倾斜数据研究意义重大.利用奇异谱迭代插值方法,对汶川地震震中附近的康定、楚雄、云龙、弥渡等4个地震台站的震前两个月的地倾斜数据进行插值,得到连续、完整的数据.利用奇异谱分析(Singular Spectrum Analysis,SSA)对插值完成的地倾斜数据进行分析.基于最小二乘原理,对经过奇异谱分析后的地倾斜数据的趋势项进行线性拟合.采用w-correlation方法对数据进行分组重构,得其残差值,并取2.5倍的标准差为阈值.结果表明:汶川地震发生前的两个月内,4个台站的地倾斜数据的趋势项均向震中位置倾斜,地倾斜数据的残差值均有超过各自阈值的情况.汶川地震发生前,康定、楚雄、云龙、弥渡等4个地震台站的地倾斜数据均有异常.

Singular spectrum analysis on ground tilt data before Wenchuan earthquake

The Wenchuan earthquake has caused serious casualties and huge economic losses. It is of great significance to study the ground tilt data before the Wenchuan earthquake. Using the singular spectrum iterative interpolation method, the ground tilt data of the four seismic stations in Kangding, Chuxiong, Yunlong and Midu near the Wenchuan earthquake epicenter are interpolated to obtain continuous and complete data. Then, the interpolated ground tilt data is analyzed using Singular Spectrum Analysis(SSA). Based on the principle of least squares, the trends of ground tilt data after singular spectrum analysis are fitted linearly. The data is reconstructed by w-correlation method, the residual is obtained, and take 2.5 times the standard deviation as the threshold. The results show that within two months before the Wenchuan earthquake, the trends of the ground tilt data of the four stations are inclined to the epicentral position, and the residuals of the ground tilt data exceed the respective thresholds. All in all, before the Wenchuan earthquake, the ground tilt data of four seismic stations, such as Kangding, Chuxiong, Yunlong and Midu, were abnormal.