利用GPS观测分析青藏高原东缘应变特征  

Characteristics of Strain at Eastern Margins of the Tibetan Plateau from GPS Data

作　　者：王帅[1] 张永志[1] 吴然[1] 姜永涛[1] 

机构地区：[1]长安大学地质工程与测绘学院,西安市雁塔路126号710054

出　　处：《大地测量与地球动力学》2015年第2期253-257,共5页Journal of Geodesy and Geodynamics

基　　金：国家自然科学基金(41374028;41304013;41274083);国土资源大调查项目(1212010914015);陕西省教育厅自然科学科研项目(12JK0798)

摘　　要：根据青藏高原东缘2004～2007年的GPS观测资料,通过多面函数法建立青藏高原东缘地壳水平运动速度场模型,给出球面坐标系下的视应变场。对照该区同期发生的地震活动,讨论了水平运动、应变场空间分布与强震和区域构造变形的关系。结果表明,松潘块体东西向地壳缩短显著,川滇块体以左旋剪切变形和顺时针转动为主。地应变特征表明,2008年汶川地震前龙门山地区为面应变能次高值区,呈面压特性,应变快速积累,龙门山断裂带中段震前处于闭锁状态。鲜水河断裂带西段南北地壳呈北东-南西向挤压缩短,东段两侧呈北西-南东向压缩。川滇菱形块体为应变能和面应变率梯度高值区,金沙江西部的应变能次高值区与羌塘块体的构造应力作用有关。The displacement model of surface horizontal motion is calculated by using a multi-surface function based on the GPS data from the eastern Tibetan plateau from 2004 to 2007,and the strain field on the spherical coordinates is given.Through comparison of earthquakes that occurred in the observation periods and the fault distribution in the area,the relationship among horizontal motion,strain space distribution,strong earthquakes and regional tectonic deformation is discussed.The results indicated that EW trending crustal shortening is remarkable in Songpan block and the deformation in Sichuan-Yunnan block is dominated by left-lateral shear and rotation.Furthermore,before the Wenchuan earthquake,the Longmenshan fault displayed a secondary high value of strain energy,the surface strain showed a pressure property,with the strain increasing rapidly,and the middle segment of the Longmenshan fault has been locked.The crustal zone in the western segment of the Xianshuihe fault shows NE-SE shortening and in the eastern segment the crustal displays NW-SE shortening.Sichuan-Yunan diamond block is an area with high value of strain energy and surface strain gradient,the western region of Jinshajiang is dominated by strong strain energy,which is associated with the tectonic stress of Qiangtang block.

关 键 词：青藏高原东缘 多面函数 龙门山断裂带 应变特征 

分 类 号：P315.72[天文地球—地震学]