摘要
利用国家重大科学工程"中国地壳运动观测网络"、"中国构造环境观测网络"和相关项目1999—2011年GPS区域站观测资料,获得了青藏高原东缘地区现今地壳水平运动速度场图像;结合地质构造动力环境和区内发生的特大地震事件,初步分析了GPS观测反映的水平运动空间分布的分区差异性和时间变化的阶段性;进而与本研究区1970s—2011年水准测量获得的垂直运动背景场进行综合对比,进一步研究和探讨了区域现今三维地壳运动的时空分布特征及其机理.结果认为:①青藏高原东缘不同构造地带水平运动强度和方式的差异,受控于青藏高原向北挤压、向东挤出和绕东构造结旋转作用;而运动状态随时间变化的阶段性(尤其是汶川地震发震断裂及其相关构造地带)与特大地震的孕育、发生有关.②现今三维地壳运动呈现的高原山地挤压缩短隆升、盆地伸展下沉的山、盆构造活动分异与构造动力环境和深部物质活动有关,反映了新构造活动的继承性.③龙门山汶川发震地段长期受压、闭锁积累的应变能经Ms8.0特大地震集中释放之后处于松弛调整运动状态,但与之相关联的构造部位以及外围的西秦岭、川滇菱形块体东边界等构造地带应变积累仍在持续.
In this paper, we derived the GPS velocity field at the eastern edge of Tibet from the campaign GPS measurement implemented by the CMONC （China Crustal Movement Observation Network） and TEONC （China Tectonic Environment Observation Networks） in 1999--2011. Then, we analyzed the time-depended features and the spatial distributions of the GPS velocity, integrating with the dynamic background and the large events in this area. At last, we investigated the characteristics and mechanism of 3D crust-movement, by comparing to the vertical movement from leveling measurements in 1970s--2011. The results indicated that： The different magnitude and direction of GPS horizontal velocity are mainly ruled by the effects of extrusion and rotation from the Tibet plateau and the mutative state of motion in different stage may also relate to the pregnancy and erupting of large earthquake （especially the seismogenic fault and the adjacent areas of Wenchuan earthquake）. The features of the crust movement are related to the dynamic environment and the activity from subsurface. This implied that themovements are inherited. （~The Longmenshan fault zone which was under compression before the Wenchuan Ms8. 0 earthquake is in the stage of relaxation and adjustment now. While, the strain energy of the north edge of Bayankela block which is close to the I.ongmenshan fault and the eastern edge of Chuandian block is still accumulating.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第10期3334-3345,共12页
Chinese Journal of Geophysics
基金
中国地震行业重大科研专项(201208009
200908029)
国家自然科学基金(40974062)资助
关键词
青藏高原东缘
GPS
水准测量
三维地壳运动
汶川地震
Eastern edge of Tibet, GPS, Leveling measurement, 3D crustal movement, Wen-Chuan earthquake
