基于GPS和InSAR数据反演龙门山断裂活动参数

发布时间：2018-10-17 08:02

【摘要】：龙门山断裂地处青藏高原东缘,该地区是中国大陆地壳运动最活跃的区域之一。研究龙门山断裂的活动机制,不仅能为我们研究青藏高原地壳运动提供科学依据,而且能为该区域地震的预测预报提供有价值的信息。本文基于GPS观测数据分析了龙门山断裂区域震后地壳运动特征,结合向位错模型,反演了龙门山断裂滑动与转动情况,其次,基于位错模型,采用GPS与InSAR形变数据,研究了平武-青川断裂的活动情况。本文所作的工作与得到的结果如下:(1)基于陆态网络09-11基准站数据,采用反距离加权法,拟合龙门山地区速度场,速度场结果显示龙门山断裂东西两侧存在速度梯度,速度变化达8mm/a。采用最小二乘法计算龙门山区域应变场,应变分布显示龙门山断裂在震后主要表现为拉张应变,断裂南段仍存在压应变积累。(2)龙门山断裂现阶段主要表现为右旋走滑兼逆冲的活动特性,走滑速率最大为3.6mm/a,逆冲速率最大为2.8mm/a。龙门山断裂存在断层旋转,但旋转的量值较小。龙门山地区地壳呈现顺时针旋转的运动趋势,与龙门山断层旋转运动有关。(3)分别利用GPS、InSAR形变数据反演平武-青川断裂三维滑动速率,对比反演结果发现,GPS反演结果主要反映断裂的走滑活动特征,InSAR反演结果主要反映断裂的倾滑活动特征。单一数据反演存在局限性,无法全面研究断层活动特性。通过GPS与InSAR形变数据联合反演可知,平武-青川断裂主要表现为右旋走滑兼逆冲的活动特性,走滑速率为1.0~1.2mm/a,逆冲速率为0.5mm/a。(4)联合反演的关键问题是相对权比的确定问题,相对权比的大小直接影响反演结果,与普通联合反演相比,相对权比的约束反演可以提高反演结果的准确性与有效性。
[Abstract]:The Longmenshan fault is located in the eastern margin of the Qinghai-Tibet Plateau, which is one of the most active crustal movements in the mainland of China. The study of the active mechanism of the Longmenshan fault can not only provide a scientific basis for us to study the crustal movement of the Qinghai-Tibet Plateau, but also provide valuable information for the prediction and prediction of earthquakes in the region. In this paper, the crustal movement characteristics of Longmenshan fault region after earthquake are analyzed based on GPS observation data, and the slip and rotation of Longmenshan fault are inversed in combination with the directional dislocation model. Secondly, based on dislocation model, GPS and InSAR deformation data are used. The activity of Pingwu-Qingchuan fault is studied. The results obtained in this paper are as follows: (1) based on the data of the land network 09-11 datum station, the inverse distance weighting method is used to fit the velocity field in Longmen Mountain area. The velocity field results show that there are velocity gradients on the east and west sides of the Longmen Mountain fault. The speed varies by 8 mm / a. The least square method is used to calculate the strain field in Longmen Mountain area. The strain distribution shows that the main strain of Longmen Mountain fault is tensile strain after the earthquake. There is still compressive strain accumulation in the southern part of the fault. (2) the Longmenshan fault is mainly characterized by dextral strike-slip and thrusting at the present stage, with the maximum strike-slip rate of 3.6 mm / a and the maximum thrust rate of 2.8 mm / a. Longmenshan fault exists fault rotation, but the value of rotation is small. The crustal movement trend in Longmen Mountain area is clockwise rotation, which is related to the rotation movement of Longmenshan fault. (3) the 3-D slip rate of Pingwu-Qingchuan fault is retrieved by using GPS,InSAR deformation data, respectively. The contrast inversion results show that the GPS inversion results mainly reflect the strike-slip characteristics of the faults, while the InSAR inversion results mainly reflect the dip slip characteristics of the faults. The single data inversion is limited, and it is not possible to study the fault activity characteristics in an all-round way. From the joint inversion of GPS and InSAR deformation data, it can be seen that the Pingwu Qingchuan fault is mainly characterized by dextral strike-slip and thrusting, with a strike-slip rate of 1.0 ~ 1.2mm / a and a thrust rate of 0.5mm / a. (4) the key problem of joint inversion is the determination of relative weight ratio. The magnitude of the relative weight ratio directly affects the inversion results. Compared with the common joint inversion, the constrained inversion of the relative weight ratio can improve the accuracy and effectiveness of the inversion results.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315.2

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