SEISMOLOGY AND GEOLOGY ›› 2014, Vol. 36 ›› Issue (3): 718-730.DOI: 10.3969/j.issn.0253-4967.2014.03.014

• CONTENTS • Previous Articles     Next Articles

THE VERTICAL COSEISMIC DEFORMATION FIELD OF THE WENCHUAN EARTHQUAKE BASED ON THE COMBINATION OF GPS AND INSAR MEASUREMENTS

SHAN Xin-jian1, QU Chun-yan1, GUO Li-min1,2, ZHANG Guo-hong1, SONG Xiao-gang1, ZHANG Gui-fang1, WEN Shao-yan1,3, WANG Chi-sheng4, XU Xiao-bo1, LIU Yun-hua1   

  1. 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
    2. Institute of Seismology, China Earthquake Administration, Wuhan 430071, China;
    3. Earthquake Administration of Xinjiang Uygur Autonomous Region, Urumqi 830011, China;
    4. Shenzhen University, Shenzhen 518060, China
  • Received:2014-02-19 Revised:2014-06-18 Online:2014-09-30 Published:2014-09-30

基于InSAR与GPS观测的汶川同震垂直形变场的获取

单新建1, 屈春燕1, 郭利民1,2, 张国宏1, 宋小刚1, 张桂芳1, 温少妍1,3, 汪池升4, 徐小波1, 刘云华1   

  1. 1. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029;
    2. 中国地震局地震研究所, 武汉 430071;
    3. 新疆地震局, 乌鲁木齐 830011;
    4. 深圳大学, 深圳 518060
  • 作者简介:单新建|男|1966年生|1999年在中国地震局地质研究所获博士学位|研究员|主要从事InSAR地壳形变观测技术及应用、地壳形变观测与动力学、卫星热红外图像与断层活动性等研究|电话:010-62009134|E-mail:xjshan@ 163.com。
  • 基金资助:

    国家自然科学基金(41340008,41111140386)和中国地震局地质研究所基本科研业务专项(IGCEA1217)共同资助

Abstract:

Vertical coseisimic deformation near seismogenic fault is one of the most important parameters for understanding the fault behavior, especially for thrust or normal fault, since near field vertical deformation provides meaningful information for understanding the rupture characteristics of the seismogenic fault and focal mechanism. Taking Wenchuan thrust earthquake for an example, we interpolate GPS horizontal observed deformation using Biharmonic spline interpolation and derive them into east-westward or north-southward deformation field. We first use reliable GPS observed value to correct InSAR reference point and unify both GPS and InSAR coordinate frame. We then make a profile using InSAR data and compare it to that from GPS data and we find GPS and InSAR observation reference point has a 9.93cm difference in the hanging wall side, and around -11.49cm in the footwall. After correction, we obtain a continuous vertical deformation field of the Wenchuan earthquake by combined calculation of GPS and InSAR LOS deformation field. The results show that the vertical deformation of both hanging wall and foot wall of the fault decreases rapidly, with deformation greater than 30cm within 50km across the fault zone. The uneven distribution of the vertical deformation has some peak values at near fault, mainly distributed at the southern section(the town of Yingxiu), the middle(Beichuan)and the northern end(Qingchuan)of the seismogenic fault. These three segments have their own characteristics. The southern section of the fault has an obvious asymmetric feature, which exhibits dramatic uplift reaching 550cm on the hanging wall, with the maximum uplift area located in Yingxiu town to Lianshanping. The middle section shows a strong anti-symmetric feature, with one side uplifting and the other subsiding. The largest uplifting of the southern segment reaches around 255cm, located at the east of Chaping, and the largest subsiding is in Yongqing, reaching around -215cm. The vertical deformation of the northern section is relatively small and distributed symmetrically mainly in the north of Qingchuan, with the maximum uplift to be 120cm, locating in the northernmost of the seismogenic fault.

Key words: Wenchuan earthquake, Biharmonic spline interpolation, combination of GPS and InSAR, vertical deformation field

摘要:

发震断层的形变是断层活动的重要参数之一,对认识断层性质、震源机理有重要作用。文中以逆冲性质为主的汶川地震为例,采用符合地表水平形变特征的Biharmonic样条插值对GPS水平形变矢量插值,然后再分解为EW和SN向分量。利用可靠的GPS观测值对InSAR参考点进行校正,统一两者的坐标系。通过对汶川地震视线向形变场剖面与GPS对比分析发现,断层上盘GPS与InSAR观测参考点相差9.93cm,而下盘则为-11.49cm。在此研究基础上,通过GPS水平形变场与InSAR视线向形变场联合解算,获取了汶川地震垂直连续形变场。结果表明,断层两侧垂直形变衰减较快,横跨断裂带形变量>30cm的宽度不超过50km;沿发震断层附近垂直形变高值区分布不均匀,主要集中分布在发震断裂的汶川县城至都江堰段、茶坪—北川—南坝段和青川段。这3段各有特色,南段断层两侧垂直形变极不对称,主要以上盘剧烈抬升为主,最大抬升区域在映秀镇至连山坪一带,抬升量达到5.5m。中段表现为较强的反对称性,断层一侧抬升另一侧沉降。该段上盘最大抬升区域在茶坪东侧,抬升量为255cm,下盘最大沉降量在永庆,沉降量为-215cm。北端垂直形变相对较小,主要分布在青川北侧,呈对称分布,在发震断层最北端,最大抬升量为120cm。

关键词: 汶川地震, Biharmonic样条插值, InSAR和GPS结合, 垂直形变场

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