摘要
对福建GPS网的5期观测数据（1995、1997、1999、2001、2003）进行了统一处理，得到4个时段（1995-1997、1997-1999、1999-2001、2001-2003）ITRF2000的站速度、福建地区的整体旋转参数和主应变参数。福建地区存在一致的南东向运动：地震前（第1时段）运动速度平均为32．1mm／a；震时和震后两年时间内（第2时段）运动速度大幅度增加到38．7mm／a；震后第2个两年（第3时段）运动速度相对于第2时段大幅度减小为30．0mm／a；震后第3个两年（第4时段），运动速率相对第3时段有较大增加并超过了第1时段。福建地区的主应变场，在震前主压应变率（12．4×10^-9／a）大于主张应变率（7．1×10^-9／a），地壳表现为弹性压缩，主压应变轴为N70．9°W；震后应变场发生了相反的变化，主压应变轴变成了主张应变轴，主张应变率（28．9×10^-9／a）大大超过主压应变率（3.7×10^-9／a），地壳表现为南东方向弹性伸展，第3时段与第4时段主压应变率逐渐增加，主压应变轴也逐渐恢复到震前的方向。福建地区从1995年到2003年地壳运动速度场与应变场随时间的变化过程，反映了集集大地震发生前后区域应力场加强、弹性应变能积累，震时和震后弹性应变能快速释放与逐渐调整恢复的过程。
After having uniformly processed observed data in the 5 period （1995, 1997, 1999, 2001 and 2003） ,the site velocities of ITRF2000 in 4 time interval （1995-1997, 1997-1999, 2000-2001, 2001-2003） ,the integral rotation parameters and principal strain parameters in Fujian region are obtained. Fujian region exhibits a consistent southeastward movement： the average velocity before the earthquake （the first time interval） was 32.1 mm/a; the velocity during the earthquake and in the two years after the earthquake （the second time interval） increased greatly to 38.7mm/a; in the second two years after the earthquake （the third time interval） it decreased rapidly,as compared to the second time interval to 30.0 mm/a ; in the third two years after the earthquake （the forth time interval） it increased greatly, as compared with the third time interval, and surpassed that in the first time interval. As regards the principal strain field in Fujian region, the principal compressive strain rate （12.4×10^-9/a） was larger than the principal tensile strain rate （7.1×10^-9/a） before the earthquake and the crust displayed elastic compression with a principal compressive strain axis of N70.9°W. After the earthquake, the strain field turned to the opposite and the principal compressive strain axis changed to the principal tensile strain axis. As a result, the principal tensile strain rate （28.×10^-9/a） was much larger than the principal compressive strain rate （3.7×10^-9/a） and the crust exhibited southeastward elastic extension. In the third and forth time interval, the principal compressive strain rates increased gradually and the principal compressive strain axis recovered gradually to the direction as before the earthquake. The variations of crustal motion velocity field and strain field with time in the period from 1995 to 2003 in Fujian region reflected the process of regional stress field strengthening, elastic strain energy accumulation, coseismic rapid release of elastic strain ene
出处
《大地测量与地球动力学》
CSCD
北大核心
2006年第2期5-9,共5页
Journal of Geodesy and Geodynamics
基金
国家自然科学基金(40474036)
关键词
集集地震
福建GPS网
站速度
应变场
弹性应变能
Chi-Chi earthquake, GPS network of Fuijan, site velocity, strain field, elastic strain energy
