圣安德烈斯断层及邻域高精度GPS速度场及地壳应变特征

发布时间：2018-03-07 12:24

本文选题：圣安德烈斯断层及其邻域　切入点：GPS　出处：《长安大学》2017年硕士论文　论文类型：学位论文

【摘要】：GPS(全球定位系统)测量技术能够快速、准确地提供测站点的精确三维坐标等信息,以高精度、全天候、准实时等显著特点在地学领域内得到愈来愈广泛的应用,可为监测全球及区域地壳形变、应变特征研究提供多尺度的高精度监测数据。本文针对圣安德烈斯断层特殊的大陆构造位置,其受到太平洋板块与北美板块共同作用。区域内地质构造复杂,地震活动频繁,使其成为地球表面最长、最活跃的构造断层带,是国际地学研究的热点区域,在强震趋势性判断研究中也具有较强的代表性。因此,利用该区域多期高精度GPS监测资料,获取区域高精度GPS运动速度场,并基于此研究了区域地壳应变特征,分析了强震活动与地壳形变应变特征的内在关系,对于掌握区域现今地壳构造活动与灾害动力学成因机制具有重要的理论与参考价值。主要研究内容及成果如下:1、本文基于圣安德烈斯断层及其邻域2010~2015年五期最新高精度GPS监测资料,利用GAMIT/GLOBK高精度数据处理软件,采用高精度数据处理策略,分别获取了全球ITRF2005框架及相对于北美板块基准下的高精度地壳运动速度场,掌握了研究区域现今地壳构造形变特征。2、通过对比分析不同参考基准下区域水平速度场得出:ITRF2005框架下圣安德烈斯断层及其邻域地壳整体朝西偏北方向运动,在帝王谷和莫哈维段速度由南向北呈顺时针旋转趋势,断层以北运动速率较小,以南运动速率较大,主要原因可能是其位于太平洋板块与北美板块交界处,受太平洋板块西北向的挤压,导致该区域GPS台站整体朝西偏北方向运动;扣除北美板块背景场运动后,研究区域整体速度值较小,位于断层西南侧靠近太平洋板块区域速度则较高,位于断层北部的北美板块上测站速度相对较低,由此反映出研究区域内部差异构造形变特征。3、在获得研究域地壳水平速度场基础上,本文进一步采用球面最小二乘配置法计算获取了研究区域地壳应变特征参数,并探讨了区域地震活动与地壳形变应变特征的内在关系。结果表明:应变高值区沿圣安德烈斯断层呈显著线状分布特征,以主压应变为主,应变率量值呈现西强东弱的差异性特点。主压应变高值区主要位于文图拉盆地和索尔顿湖附近。根据地震资料记载,本文进一步揭示出区域内应变率高值区也是中强地震的频发区域。
[Abstract]:GPS (Global Positioning system) measurement technology can quickly and accurately provide accurate three-dimensional coordinate information of the survey site. It has been more and more widely used in the field of geoscience with the remarkable characteristics of high precision, all-weather, quasi-real-time and so on. It can be used to monitor global and regional crustal deformation and strain characteristics with high precision data. This paper deals with the special continental tectonic location of the San Andreas fault. It is subjected to the interaction of the Pacific plate and the North American plate. The complex geological structure and frequent seismic activity make it the longest and most active tectonic fault zone on the earth's surface. Therefore, using the multi-period and high-precision GPS monitoring data, the velocity field of regional high-precision GPS motion is obtained, based on which the crustal strain characteristics of the region are studied. The relationship between strong earthquake activity and crustal deformation and strain characteristics is analyzed. It has important theoretical and reference value for mastering the mechanism of crustal tectonic activity and disaster dynamics in the region. The main research contents and results are as follows: 1. Based on the San Andreas fault and its adjacent regions, the fifth issue of 2010 ~ 2015 is the latest in this paper. High precision GPS monitoring data, Using the GAMIT/GLOBK high precision data processing software and the high precision data processing strategy, the global ITRF2005 frame and the high precision crustal movement velocity field relative to the North American plate datum are obtained, respectively. The characteristics of present crustal tectonic deformation in the studied region are mastered. By comparing and analyzing the regional horizontal velocity field under different reference datum, it is concluded that the San Andreas fault and its adjacent crust move northwestward under the framework of the 10 ~ (th) ITRF2005. In the monarch valley and Mojave section, the velocity rotates clockwise from south to north, the movement rate is small in the north of the fault and the velocity in the south is larger. The main reason may be that it is located at the junction of the Pacific plate and the North American plate. Due to the northwestern compression of the Pacific plate, the whole GPS station in the region moves northwestward, and after deducting the background motion of the North American plate, the overall velocity of the studied region is relatively small. On the southwest side of the fault near the Pacific plate, the velocity is relatively high, and the North American plate located in the north of the fault has a relatively low velocity. This reflects the characteristics of differential tectonic deformation within the studied region. Based on the horizontal velocity field of the crustal in the study area, the crustal strain characteristic parameters of the studied region are obtained by using the spherical least square collocation method. The relationship between regional seismicity and crustal deformation and strain characteristics is also discussed. The results show that the high strain region has a remarkable linear distribution along the San Andreas fault, and the principal compressive strain is the main strain. The strain rate values show the difference between the east and the west. The high value area of the principal compressive strain is mainly located near the Ventura basin and Lake Solton. According to the seismic data, This paper further reveals that the high value region of strain rate is also the frequent region of moderate earthquakes.
【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】：P228.4;P542

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