最小二乘配置下的新疆地区地壳形变动态分析

Analysis of dynamic crustal deformation in Xinjiang by least square collocation

为了研究新疆地区地壳形变动态变化特征,本文搜集整理了国内外发表的多期中国大陆GPS观测资料,获取1992~2016年间新疆地区的4期GPS实测速度场,运用最小二乘配置法对实测速度场进行插值,构建研究区地壳运动模型和应变率场。结果表明:实测速度场中,平均的GPS最小站间距由1992~2001年间的84.7 km减小到1992~2016年间的28.6 km,点位覆盖密度增大了约3倍;利用最小二乘配置法插值后的地壳运动模型与实测速度场具有很好的一致性,并且地壳运动模型与应变率场反映出1992~2016年间构造运动与变形较稳定,是对区域长期构造运动与变形的继承。研究区内的乌恰地区和伊塞克湖附近的面应变和最大剪应变变化最大,应变高值区逐渐自西向东扩张,反映出帕米尔高原对天山造山带的持续推挤还在增强;而塔里木盆地、准噶尔盆地和哈萨克斯坦块体的应变量基本不发生变化,说明3大块体内部基本不发生变形,反映了其刚性的特征;研究区最大剪应变率和地震发生率的相关性研究表明二者相关性显著,说明应变积累和地震活动有较好的对应关系。

In order to study the dynamic characteristics of crustal deformation in Xinjiang, we collected the published GPS data of Chinese mainland at home and abroad, and acquired the four phase GPS velocity field in Xinjiang from 1992 to 2016. Interpolating the measured velocity field with least square collocation method, constructed the crustal movement model and strain rate field in the study area. The average minimum GPS station spacing decreased from 84.7 km in 1992~2001 to 28.6 km in 1992~2016, and the point coverage density increased by about three times. The crustal movement model interpolated by the least square collocation method is in good agreement with the measured velocity field, and the crustal movement model and strain rate field reflect the relatively stable tectonic movement and deformation from 1992 to 2016, which is the inheritance of regional long-term tectonic movement and deformation. The surface strain and maximum shear strain in the Wuqia region and near Isek Lake in the study area change the most, and the high value area of strain gradually expands from west to east, reflecting that the continuous extrusion of Pamir Plateau to Tianshan orogenic belt is still strengthening. The strain of Tarim Basin, Junggar Basin and Kazakhstan block basically don ’ t change, indicating that the three blocks basically do not deform, reflecting their rigid characteristics. The two periods of maximum shear strain accumulation maps reflect the accumulation of crustal energy in Xinjiang is slow, and the high value area of maximum shear strain corresponds well to strong earthquake activity. The correlation between the maximum shear strain rate and earthquake occurrence rate in the study area shows that the correlation between the two is significant, indicating that there is a good corresponding relationship between seismicity and strain accumulation.