基于InSAR数据的川西地区断层活动研究

发布时间：2018-05-27 06:30

本文选题：合成孔径雷达干涉测量 + 时间序列　；参考：《长安大学》2017年博士论文

【摘要】：常规的断层活动监测手段(如水准测量和全球定位系统等)只能监测有限的离散点,而合成孔径雷达干涉测量是一种基于面观测的形变监测手段,具有空间分辨率高,全天时全天候观测的特点,弥补了基于点观测的低空间分辨率形变监测的不足,为研究地震活动提供了有利条件,也为基于大地测量技术的断层滑动反演研究提供了精细的观测数据。在研究断层活动方面,多采用的是位错理论模型,但此模型对一些观测到的位移场旋转运动不能进行解释。对于具体的断层活动与地面大地形变场问题,向错理论描述了在弹性介质中断层面之间的相互转动与地表面变形之间的理论关系。本文采用一种新的模型向-位错组合模型,以位错理论和向错理论为基础,同时考虑断层的滑动和转动,选择地壳旋转变形的典型区域川西地区,分别以龙门山断裂和鲜水河断裂为例,利用InSAR数据获取汶川同震形变场和鲜水河断裂西北段的时间序列及年平均形变速率,并基于向-位错组合模型对两条断裂的滑动与转动进行反演计算。本文主要研究内容和贡献如下:(1)针对位错理论模型无法描述断层的转动问题,本文采用一种新的模型—向-位错组合模型,模拟断层的滑动和转动,建立了断层滑动和转动与地面变形的关系。该模型结合描述断层滑动的位错模型和描述断层转动的向错模型两大模型的优势,能有效模拟断层的活动方式。该模型成功模拟了单一断层的转动特征。(2)针对汶川同震C波段的雷达卫星在龙门山上盘山区得到的卫星信号很大程度上不可用的问题,本文选用波长可达23.6cm的ALOS PALSAR L数据,采用覆盖汶川地震前后6个轨道的影像,利用D-InSAR的二轨法进行差分干涉测量;为了确保各轨道之间、轨道内数据的连续性,本文分别采用加权拼接羽化、最底层拼接羽化、基于几何的拼接羽化三种方法进行拼接,最终通过加权拼接羽化方法拼接的汶川同震形变场拼接处形变连续,影像的整体感增强。(3)为了降低InSAR数据的数据量、数据噪声、冗余数据对反演计算效率的影响,本文提出了一种改进的立方卷积重采样方法,该方法是在主要形变区域采样点密集,在非主要形变区域,采样点稀疏,解决了传统立方卷积方法均匀采样且数据量大的问题,较好地保存了InSAR数据的细节信息。利用该方法实现了汶川同震形变场和鲜水河断裂西北段年平均形变速率图的降采样。(4)针对龙门山断裂在同震过程中发生转动的特点,本文基于向-位错组合模型,采用粒子群算法,首次利用GPS和InSAR数据联合反演龙门山断裂带的滑动和转动,并与GPS数据反演的龙门山断裂带的滑动和转动进行比较,结果表明:基于向-位错组合模型反演的龙门山断裂带活动特征,相比位错模型反演结果,更加符合龙门山断裂带的倾滑面是铲状曲面的特点;GPS和InSAR联合反演相比GPS反演,走滑速率、倾滑速率略微偏小,转动角较大,断层的转动特性表现得更明显。(5)为了研究汶川地震对鲜水河断裂活动的影响,针对鲜水河断裂形变缓慢的特点,本文采用汶川地震后约一年的覆盖鲜水河断裂西北段的8景Envisat ASAR C波段影像,利用SBAS_InSAR方法,成功获得鲜水河断裂西北段的时间序列,使用Stacking技术成功获得鲜水河断裂西北段的年平均形变速率。(6)针对鲜水河断裂存在转动的特点,本文基于向-位错组合模型,采用粒子群算法,首次利用InSAR数据实现了鲜水河断裂西北段的滑动和转动反演,结果表明:汶川地震后,鲜水河断裂的张裂速率、走滑速率相比已有结果数值上略微偏大;断层转动的分段性特征较滑动更明显。
[Abstract]:Conventional monitoring methods of fault activity (such as leveling and global positioning system) can only monitor the finite discrete points, and synthetic aperture radar interferometry is a deformation monitoring method based on surface observation, which has high spatial resolution and full weather all day observation, which makes up for low spatial resolution deformation monitoring based on point observation. The lack of measurement provides favorable conditions for the study of seismic activity, and provides fine observation data for the study of fault slip inversion based on Geodetic technique. In the study of fault activity, the most used is the dislocation theory model, but the model can not explain some observed displacement field rotation motion. The theoretical relationship between the rotation and the surface deformation between the interruption layers of the elastic medium is described by a new model of the model direction and dislocation model, based on the dislocation theory and the error theory, and the slip and rotation of the faults are taken into consideration, and the rotation of the earth's crust is chosen. In the typical area of Western Sichuan, the Longmen Mountain Fault and the fresh water river fault are taken as an example. The time series and the annual mean change rate of the Wenchuan same earthquake deformation field and the northwest segment of the fresh water river fault are obtained by InSAR data, and the slip and rotation of the two faults are calculated based on the combination model of the direction and dislocation. The main study is in this paper. The contents and contributions are as follows: (1) in this paper, the dislocation theory model can not describe the problem of fault rotation. In this paper, a new model, direction and dislocation model, is used to simulate the slip and rotation of faults. The relationship between fault slip and rotation and ground deformation is established. This model combines the dislocation model describing the fault slip and the direction of describing the rotation of fault. The advantages of the two model of the wrong model can effectively simulate the active mode of the fault. The model successfully simulates the rotation characteristics of a single fault. (2) the satellite signals obtained from the Wenchuan mountain C band in the mountains of Longmen mountain are largely unavailable, and this paper selects ALOS PALSAR L data with wavelengths of up to a wavelength, and Using the images of 6 tracks before and after the Wenchuan earthquake, the difference interference measurement is carried out by the two rail method of D-InSAR. In order to ensure the continuity of the data between the tracks and the orbit, this paper uses the weighted splicing and emergence, the bottom splicing and emergence, and the stitching and emergence based on geometric splicing and feathering, and finally through the weighted splicing of the feathering side. The stitching of Wenchuan same earthquake deformation field stitching in Wenchuan is continuous and the image integrity is enhanced. (3) in order to reduce the amount of data, data noise, and the effect of redundant data on the efficiency of inversion, an improved cubic convolution resampling method is proposed in this paper, which is dense at the sampling points in the main deformation regions and in the non main shape. The sampling point is sparse, which solves the problem that the traditional cubic convolution method is uniformly sampled and has a large amount of data. The detailed information of InSAR data is well preserved. Using this method, the reduction sampling of the annual mean shape change rate graph of the Wenchuan same earthquake deformation field and the northwest segment of the fresh water river fault is realized. (4) the Longmen mountain fault occurs during the same earthquake process. In this paper, based on the combination of directional dislocation model and particle swarm optimization (PSO), the paper uses GPS and InSAR data to inverse the slip and rotation of the Longmen mountain fault zone for the first time, and compares the slip and rotation of the Longmen mountain fault zone with the GPS data inversion. The results show that the activity of the Longmen Mountain Fault Zone Based on the combination model of the direction dislocations is reversed. Compared with the inversion results of the dislocation model, the slip surface of the Longmen mountain fault zone is more consistent with the feature of the spade surface; the joint inversion of GPS and InSAR is compared with the GPS inversion, the strike slip rate is slightly smaller, the rotation angle is larger and the rotation characteristic of the fault is more obvious. (5) in order to study the impact of the Wenchuan earthquake on the fresh water river fracture activity, In view of the slow fracture deformation of the fresh water river, this paper uses 8 Envisat ASAR C band images covering the northwest segment of the fresh water river fault about one year after the Wenchuan earthquake. Using the SBAS_InSAR method, the time series of the northwest segment of the fresh water river fault is successfully obtained. The annual mean shape change of the northwest segment of the fresh water river fault is successfully obtained by using Stacking technology. (6) (6) in view of the rotation of the fresh water river fault, this paper uses the particle swarm optimization model and the particle swarm optimization (PSO) algorithm to make the first use of InSAR data to retrieve the sliding and rotational inversion of the northwest segment of the fresh water river fault. The results show that after the Wenchuan earthquake, the rate of the breaking rate of the fresh water river fracture is slightly larger than that of the existing results. The sectional characteristics of the fault rotation are more obvious than that of sliding.
【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P227;P315.7

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