Improving the Spatial and Temporal Resolution of Strain Rate Models of Continental Deformation

提高大陆变形应变率模型的空间和时间分辨率

• 批准号: 0911754
• 负责人: Cornelis Kreemer
• 金额: $ 28.06万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911754&HistoricalAwards=false
• 关键词: Improving; Spatial; Temporal; Resolution; Strain

One consequence of plate tectonics is that in continental plate boundary zones, such as eastern Asia and western United States, tectonic deformation (and the associated earthquake activity) can be distributed over large areas. There are essentially two satellite-based observation methods with which this deformation can be accurately monitored. With the Global Positioning System (GPS) we can precisely measure the Earth's surface motion at the locations of GPS monuments. With the help of continuous GPS (CGPS) measurements, we can now track these motions (horizontal and vertical) on a daily basis. The other methodology is called InSAR, which uses radar images to map detailed changes in the surface of a large swath of land between two (infrequent) satellite passes. A limitation of InSAR is that it is most sensitive to vertical ground motions, which often have anthropogenic instead of tectonic origins. This project aims to bridge the gap between the ability of GPS and InSAR to capture fundamental deformation processes at high spatial and temporal resolution. InSAR-detected crustal motions are limited by being sampled intermittently and only in the satellite's line-of-sight (LOS). On the other hand, GPS-derived descriptions of the deformation field fail to achieve the same spatial resolution that is obtained with InSAR. The goal of project is to significantly improve the spatial resolution of existing secular strain rate tensor models using horizontal GPS velocities, and create additional models of time-variable deformation using continuous GPS (CGPS) data. This project will provide useful baseline estimates of secular and time-dependent horizontal deformation that could aid the interpretation of InSAR results, while also allowing new advances in studies of the geodynamics and seismic hazard of areas undergoing continental deformation. The work is focussed on the Pacific-North America (PA-NA) plate boundary zone, the Mediterranean and Middle East, and central and eastern Asia. There, all publicly available CGPS data will be analyzed and combined with estimates of the secular motions from published campaign-style GPS measurements. The horizontal velocities will be converted to continuous strain rate tensor models of secular deformation. Where data coverage is limited, other kinematic indicators (e.g,, fault slip rates/vectors, earthquake focal mechanisms) will be included for additional constraints on the strain style and localization. Improvements on the temporal variation of the strain rate field (most notably due to transients and postseismic deformation) will be limited to the PA-NA plate boundary zone, where CGPS sites are abundant. Reliable time-variable strain rate models (and associated changes in dilatational and shear strain) can likely be created for 1-4 week time windows, sufficient to capture most first order time-variable processes. Both static and dynamic deformation results will be converted to LOS equivalents for 1st order comparison with InSAR results. Estimates of the secular motions of CGPS sites as well as strain rate results (tensor parameters, maps, and movies) will be made available on a dedicated web portal, as a valuable tool for scientists and educators. Secular strain rates correlate closely with expected seismic hazard and can contribute directly to improving hazard maps. The time-dependent strain rate models may contribute to investigations in stress transfer, earthquake triggering and, ultimately, time-dependent seismic hazard.Through the project, a graduate student will be trained in the management of GPS data, the characterization of CGPS time-series, and crustal deformation modeling. The results (data and models) obtained from this project will be made available on a dedicated web portal, as a valuable tool for scientists and educators.

板块构造的结果是，在大陆板边界区域（例如东亚和美国西部）中，可以在大面积上分布构造变形（以及相关的地震活动）。基本上有两种基于卫星的观察方法可以准确监测这种变形。使用全球定位系统（GPS），我们可以精确地测量GPS纪念碑位置的地球表面运动。借助连续的GPS（CGP）测量，我们现在可以每天跟踪这些动作（水平和垂直）。另一种方法称为INSAR，它使用雷达图像来绘制两个（不经常）卫星通道之间大片土地表面的详细变化。 Insar的一个局限性是它对垂直地面运动最敏感，垂直地面运动通常具有人为的而不是构造起源。该项目旨在弥合GPS和INSAR在高空间和时间分辨率下捕获基本变形过程的能力之间的差距。在卫星的视线（LOS）中，通过间歇性采样而受到限制，未检测到的地壳运动受到限制。另一方面，变形场的GPS衍生描述无法实现与InsAR获得的相同空间分辨率。项目的目的是通过水平GPS速度显着改善现有的世俗应变率张量模型的空间分辨率，并使用连续GPS（CGP）数据创建其他时间变化的模型。该项目将提供有用的基线估计值，并依赖时间依赖时间的水平变形，这可以帮助解释InsAR结果，同时还可以在研究大陆变形区域的地球动力学和地震危害方面进行新的进步。 这项工作的重点是太平洋北美（PA-NA）板块边界区，地中海和中东以及中部和东亚。在那里，将分析所有公开可用的CGP数据，并结合发布已发表的广告系列GPS测量的世俗动作的估计。水平速度将转换为世俗变形的连续应变张量张量模型。如果数据覆盖范围有限，则将包括其他运动学指标（例如，断层滑移速率/向量，地震焦点机制），以进行有关应变样式和定位的其他限制。应变速率场的时间变化的改善（最著名的是瞬态和后视变形）将限于PA-NA板边界区域，其中CGPS位点丰富。可以在1-4周的窗口中创建可靠的时间变量应变率模型（以及扩张和剪切应变的相关变化），足以捕获大多数一阶时时间变量过程。静态变形结果和动态变形结果均将转换为LOS等效物，以进行一阶比较与InsAR结果。 CGP站点的世俗动作以及应变率结果（张量参数，地图和电影）的估计值将在专用的Web门户网站上提供，作为科学家和教育工作者的宝贵工具。世俗应变率与预期的地震危害密切相关，并可以直接有助于改善危险图。时间依赖性的应变率模型可能有助于调查压力转移，地震触发和最终依赖时间依赖的地震危害。通过该项目，将对GPS数据的管理进行培训，CGPS时间的表征 - 系列和地壳变形建模。从该项目获得的结果（数据和模型）将在专用的Web门户网站上提供，这是科学家和教育工作者的宝贵工具。