A GPS Study of the Large-Scale Neotectonics of Northern Central America

中美洲北部大范围新构造运动的 GPS 研究

• 批准号: 0309839
• 负责人: Dennis DeMets
• 金额: $ 16.18万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0309839&HistoricalAwards=false
• 关键词: GPS; Study; Large; Scale; Neotectonics

This project is a five-year collaborative geodetic study of the large-scale neotectonics of northern Central America, where the western end of the Caribbean plate abuts both the Middle America subduction zone and Motagua-Polochic strike-slip fault system. The scientific objectives are as follows: (1) Estimate the magnitude and distribution of frictional coupling along the Cocos-Caribbean subduction interface, (2) Measure the rate of strike-slip motion at one or more points across the Motagua-Polochic fault system, (3) Measure extension across the Central American "basin-and-range" south of the Motagua-Polochic fault system, (4) Measure how quickly strain accumulates across faults in the Central American volcanic arc that accommodate dextral forearc shear in response to oblique subduction, (5) Test whether significant regional uplift occurs, possibly in response to the hypothesized detachment of the slab subducting beneath this region, and (6) Improve kinematic models of the Caribbean plate geodetic reference frame. Work on the first objective is contributing to an emerging understanding of the fundamental role of aseismic processes in accommodating subduction. Progress on objectives 2-5 is advancing the present poor understanding of the neotectonics and seismic hazards at the western, trailing edge of the Caribbean plate. Work on the final objective benefits multiple NSF-sponsored GPS studies of deformation around the complexly deforming margins of the Caribbean plate. These objectives are being accomplished through modeling of velocities determined from annual or more frequent occupations of 50-100 GPS sites distributed throughout Honduras, Guatemala, and El Salvador and velocities at seven continuous GPS sites that are already operating in these countries. Modeling is done using three-dimensional finite element code that allows for a tectonically realistic representation of the study area, including laterally- and vertically-varying material properties representative of an ocean-continent subduction boundary. All measurements are made by local scientists, except for the initial network reconnaissance and installation, which were a collaborative effort.The project is structured to benefit significantly the research careers of Honduran, Guatemalan, and Salvadoran scientists with whom are collaborating. The budget includes annual operating funds, GPS receivers, and travel funds for Honduran seismologist and Guatemalan seismologists, and possibly an earth scientist from El Salvador. Ultimately, progress on the goals above will improve estimates of the likely frequency of significant earthquakes along a variety of faults that present a seismic hazard in this extensive region.

该项目是一项为期五年的合作大地测量研究，针对中美洲北部的大规模新构造运动，加勒比板块的西端毗邻中美洲俯冲带和莫塔瓜-波洛奇走滑断层系统。 科学目标如下：（1）估计沿着科科斯-加勒比俯冲界面的摩擦耦合的大小和分布，（2）测量莫塔瓜-波洛奇断层系统中一个或多个点的走滑运动速率，（3）测量莫塔瓜-波洛奇断层系统以南的中美洲“盆地和山脉”的延伸，（4）测量在莫塔瓜-波洛奇断层系统中应变在断层上积累的速度。 中美洲火山弧适应斜向俯冲反应中的右前弧剪切，（5）测试是否发生显着的区域隆起，可能是响应该区域下方俯冲的板片的假设分离，以及（6）改进加勒比板块大地测量参考系的运动学模型。 第一个目标的工作有助于人们逐渐了解地震过程在俯冲过程中的基本作用。 目标 2-5 的进展正在加深目前对加勒比板块西部后缘新构造运动和地震灾害的了解。 最终目标的实现有利于多项 NSF 赞助的关于加勒比板块复杂变形边缘变形的 GPS 研究。 这些目标是通过对分布在洪都拉斯、危地马拉和萨尔瓦多的 50-100 个 GPS 站点每年或更频繁的占用情况以及这些国家已经运行的 7 个连续 GPS 站点的速度进行建模来实现的。 建模是使用三维有限元代码完成的，可以在构造上真实地表示研究区域，包括代表海洋-大陆俯冲边界的横向和垂直变化的材料属性。 除了最初的网络勘察和安装之外，所有测量均由当地科学家进行。该项目的结构旨在使合作的洪都拉斯、危地马拉和萨尔瓦多科学家的研究事业受益匪浅。 预算包括年度运营资金、GPS 接收器以及洪都拉斯地震学家和危地马拉地震学家以及可能来自萨尔瓦多的地球科学家的旅行资金。 最终，上述目标的进展将改善对这一广阔地区存在地震危险的各种断层沿线发生重大地震的可能频率的估计。