基于迭代PCA的GPS时间序列震后形变估计方法和应用

GPS时间序列的震后形变分析对于研究区域震后形变机制和岩石圈流变学特性以及维持国际动态地球参考框架具有重要意义.本文在现有参数估计方法的基础上,提出兼顾震后形变衰减特征空间相关性和整体建模的"迭代PCA参数估计方法",并利用模拟数据证实了新方法可以获取更稳健可靠的震后形变、同震形变和震间速度参数.最后,以37个新西兰GPS连续站坐标时间序列为例,利用迭代PCA方法提取了2016年11月13日Kaikoura地震共性的震后形变时间演化过程和各站点的震后形变,并定量分析了震后形变对地表速度的影响.结果表明各站的震后形变在时间域上以衰减常数τ为4天的对数模型持续松弛;空间域上南岛北东部和北岛最南部震后形变较大,其中,最大震后形变点为cmbl站,截至2017年6月10日NEU方向累计的震后形变分别达到107mm,135mm和187mm,地表速度分别达到133.58mm·a-1,112.05mm·a-1和175.58mm·a-1,仍高于稳定的震间速度.

Iterative PCA estimation and its application to postseismic deformation from GPS coordinate time series

Analysis of postseismic deformation from GPS coordinate time series is of great significance for earth science such as the mechanism of postseismic deformation and rheology of lithosphere as well as the maintenance of dynamitic Terrestrial Reference Frame. On the basis of the current parameter estimation method for GPS coordinate time series, we proposed an iterative PCA method which takes both the spatial correlation of postseismic deformation and overall modeling into account, and proved its advantages in estimating more robust parameters with the simulated data. Then, we processed the coordinate time series of 37 continuous GPS sites located in New Zealand using this iterative PCA method, obtained the common temporal postseismic process along with the spatial postseismic amplitude for the 13 November 2016 Kaikoura earthquake, and investigated the postseismic effect on the surface velocity. The results show that GPS stations are logarithmically relaxing with a decay constant of 4 days in the temporal domain. The northeastern part of South Island and the southernmost of North Island are of maximum deformation in the spatial domain. Until 10 June 2017, the accumulated deformation in NEU direction of the cmbl station reached 107 mm,135 mm,187 mm, respectively, which is the site of largest postseismic deformation, while the ground surface velocities of cmbl were up to 133.58 mm·a^-1,112.05 mm·a^-1,175.58 mm·a^-1 which remain higher than the interseismic rate.