GPS时间序列及其对昆仑山口西8.1级地震的响应  

GPS TIME-SERIES AND ITS RESPONSE TO M_S=8.1 KUNLUNSHAN EARTHQUAKE

作　　者：敬少群[1] 吴云[1] 乔学军[1] 周硕愚[1] 施顺英[1] 

机构地区：[1]中国地震局地震研究所

出　　处：《地震学报》2005年第4期394-401,466,共8页Acta Seismologica Sinica

基　　金：国家自然科学基金项目(40074024;40304002);国家"十五"科技攻关项目(2001BA601B02)联合资助.

摘　　要：采用GIPSY软件解算的站点坐标时间序列,对我国25个GPS基准站的观测数据进行了分析.结果表明,该时间序列存在明显的趋势变化,经向坐标与纬向坐标的趋势变化反映了各站点在全球板块中的运动;垂直方向的趋势变化揭示的可能是大尺度的构造信息,也可能是站点周围局部运动的反映.分析还表明,该时间序列存在明显的近乎1年的年变周期,但具体原因还有待于进一步研究.最后,就该时间序列对昆仑山口西8.1级地震的响应进行了分析.结果表明:GPS时间序列对该地震的孕育过程反映明显,并根据时间进程及异常特点将昆仑山口西8.1级地震的孕育过程分为3个阶段:块体受力状态的变化、应力积累和能量的快速积累与缓慢释放.在8.1级地震孕育的初始阶段和临震、同震及震后恢复阶段,垂直方向的异常占据主导地位,初始阶段垂直方向的异常运动导致断层间闭锁;而在地震孕育的中期,各块体间水平方向的差异运动则占主导地位,它是引起能量在断层闭锁段积累的重要原因.In this paper, observation data in 25 GPS reference stations of China have been analyzed by calculating GPS position coordinate time-series with GIPSY. Result shows there is an obvious trend variation in such time-series. The trend variations of time series along the longitudinal and latitudinal coordinates reflect the motion of each position in the global-plate, in which the trend variation in the vertical direction reveals some large-scale construction information or reflects the local movement around the positions. The analysis also shows that such time-series have a variation cycle of nearly 1.02 year, but the reason still remains to be further studied. At the end of this paper, response of the time-series to M_S=8.1 Kunlunshan earthquake was analyzed, and the earthquake preparation of M_S= 8.1 Kunlunshan earthquake, according to the time proceeding and the feature of anomaly, was divided into 3 phases-forces change exerted on blocks, strain accumulation, quick accumulation and slow release of energy. At the initial stage of seismogenic process of M_S=8.1 earthquake and at the imminent earthquake, coseismic process as well as during the post earthquake recovery, anomaly in vertical direction is always in a majority. The anomalous movement in vertical direction at the initial stage resulted in a blocking between faults, while at the middle stage of seismogenic process, the differential movement between blocks are in a majority, which is the major reason causing energy accumulating at the blocking stage of faults.

关 键 词：GPS时间序列 趋势变化 周期变化 地震孕育 断层间闭锁 能量积累 

分 类 号：P315.725[天文地球—地震学]