基于ALOS卫星数据的汶川地震地表形变特征研究

发布时间：2018-12-15 02:29

【摘要】：2008年5月12号汶川地区爆发了Mw7.9强烈地震,此次地震主断裂带一直延续到青川县苏河北侧附近,针对这次地震,本文尝试分为两个阶段研究地表形变特征,分别为同震和震后。分别采用D-InSAR和SBAS等先进大地测量技术构建汶川地震同震形变场,探究断层迁移规律,及震后开展大面积山区地表形变监测研究。具体如下:1、简述InSAR、D-InSAR、SBAS-InSAR基本原理以及数据处理步骤,对于数据处理过程中产生的误差项(大气误差,轨道基线误差等)采用了相应的程序进行削弱,对自适应滤波,Boxcar滤波和Goldstein滤波在此次地震数据处理的优缺点进行了对比,同时说明了合适的窗口和滤波次数对滤波效果的重要性。2、对6轨道60景ALOS/PALSAR L波段数据在干涉前进行了邻轨拼接与MSP预处理,在获取了汶川地震同震形变场后并基于最小邻近法再次进行了拼接与矫正。利用“中国地壳运动观测网络”公布的38个连续GPS站和435个移动GPS观测站,将其投影到LOS向,基于远近场、等值线、剖面线等评定InSAR观测的可靠性。针对震后的安(县)茂(县)地区形变研究,共选择11景PALSAR影像(2008.10.21-2010.10.27),采用SBAS-InSAR技术获取时间形变序列及平均形变速率,分别以西南部的石鼓乡一带和东南部的沸水镇为中心分析与降水的关系。3、结果表明:同震形变场覆盖龙门山断裂带两侧83194km2,断层附近形变梯度较大,具有分段性、逆冲性。条纹沿该断层呈环绕分布,整体呈西北盘抬升,东南盘下降。本次监测确定的宏观震中位置为31.05°N,103.30°E,本次监测近场σ为16.9cm,远场σ为4.5cm。震后的安茂地区东南部呈抬升趋势,抬升速率为15-30mm/y,东北和西南下沉趋势明显,沉降速率为20-45mm/y,在六、七月份形变速率加速,与当地降水量也有一定关系。整体来看与汶川地震同震形变特征具有一定吻合和趋势性,与前人研究成果一致。
[Abstract]:A strong Mw7.9 earthquake broke out in Wenchuan area on May 12, 2008, and the main fault zone of this earthquake continued to be near the north side of Suhe River in Qingchuan County. In view of the earthquake, this paper attempts to study the characteristics of surface deformation in two stages. They are coseismic and post-earthquake respectively. Advanced geodetic techniques such as D-InSAR and SBAS are used to construct the co-seismic deformation field of Wenchuan earthquake, to explore the law of fault migration, and to study the monitoring of surface deformation in mountainous areas after the earthquake. The details are as follows: 1. The basic principle of InSAR,D-InSAR,SBAS-InSAR and the steps of data processing are briefly described. The corresponding program is used to weaken the error items (atmospheric error, orbit baseline error, etc.) produced in the process of data processing. The advantages and disadvantages of adaptive filtering, Boxcar filtering and Goldstein filtering in the seismic data processing are compared. The data of 60 ALOS/PALSAR L band of 6 orbit were spliced and MSP preprocessed before interference. After obtaining the deformation field of Wenchuan earthquake, the data were spliced and corrected again based on the minimum proximity method. By using 38 continuous GPS stations and 435 mobile GPS stations published by China crustal Movement observation Network, the reliability of InSAR observation is evaluated based on far and near field, isoline and profile. Based on the study of deformation in Maomao (county) area after the earthquake, 11 PALSAR images (2008.10.21-2010.10.27) were selected, and the time deformation sequence and average deformation rate were obtained by SBAS-InSAR technique. The relationship between precipitation and precipitation is analyzed in the south west of Shigu township and the southeastern part of Beshui town. 3. The results show that the coseismic deformation field covers 83194 km2 on both sides of the Longmenshan fault zone, and the deformation gradient near the fault is large, which is segmented and thrusting. The stripes are distributed around the fault, the whole is uplifted by the northwestern plate, and the southeastern plate is decreased. The macro epicenter position determined by this monitoring is 31.05 掳Nu 103.30 掳E, the near field 蟽 is 16.9 cm, and the far field 蟽 is 4.5 cm. In the southeast of Anmao area after the earthquake, the uplift rate is 15-30mm / y. the subsidence trend of northeast and southwest is obvious, the subsidence rate is 20-45mm / y. the deformation rate accelerates in June and July, which is also related to the local precipitation. On the whole, the characteristics of coseismic deformation of Wenchuan earthquake are consistent and trending, and are consistent with previous research 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】：P315.7

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