Collaborative Research: An Integrated GPS and Structural Study of the Cocos-Caribbean Boundary in Nicaragua and El Salvador

合作研究：尼加拉瓜和萨尔瓦多科科斯-加勒比边界的综合 GPS 和结构研究

• 批准号: 0538131
• 负责人: Dennis DeMets
• 金额: $ 27.22万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0538131&HistoricalAwards=false
• 关键词: Collaborative; Research; Integrated; GPS; Structural

In this four year geodetic and structural study of the Cocos-Caribbean convergent margin along the Pacific coasts of El Salvador and Nicaragua, where a combination of oblique convergence, a prominent bend in the trench, and weak or no locking of the subduction interface, University of Wisconsin and University of Arkansas researchers are studying how a volcanic arc and forearc sliver deform in response to oblique convergence. Through Digital Elevation Model analysis, structural field work, GPS observations, and forward and inverse modeling using a three-dimensional, geometrically realistic subduction/forearc finite element mesh, the team is addressing the following important problems: (1) whether changes in convergence obliquity due to bends in trenches are efficiently transferred into changes in forearc motion or deformation and whether escape of a forearc sliver toward the trench (a free surface) is favored over crustal thickening at the leading edge of a forearc sliver; (2) why the bend between the two forearc slivers, where crustal thickening is expected, is instead occupied by a topographic depression (the Gulf of Fonseca); (3) whether the motions of the two forearcs are accommodated by arc-parallel strike-slip faulting, bookshelf faulting, or some combination of the two; (4) whether the east-west stretching characteristic of the crust inboard from the Salvadoran volcanic arc also extends into the forearc and if so, how this stretching interacts with and influences sliver transport. Finally, a series of modeling experiments are being conducted to better understand the kinematics and dynamics of the subduction/forearc wedge system, using a three-dimensional finite element model and a series of plausible boundary conditions, including dip-slip tractions at the base of the wedge, variable resistance to slip along the subduction interface and forearc faults, and varying degrees of buttressing at the leading edge of the wedge. Through this integrated approach to studying active deformation in western Central America with GPS and field-based structural work, the conceptual and kinematic framework for understanding the earthquake cycle in this region is being established. , Tens of thousands of deaths have occurred since 1900 during numerous moderate and large magnitude earthquakes in this region. Knowledge and technology transfer to El Salvadoran and Nicaraguan collaborator significantly benefit future earthquake hazard studies in both countries. Graduate students are being trained in the use of structural geology and high-precision geodesy for studying the earthquake cycle.

In this four year geodetic and structural study of the Cocos-Caribbean convergent margin along the Pacific coasts of El Salvador and Nicaragua, where a combination of oblique convergence, a prominent bend in the trench, and weak or no locking of the subduction interface, University of Wisconsin and University of Arkansas researchers are studying how a volcanic arc and forearc sliver deform in response to oblique收敛。通过数字高程模型分析，结构现场工作，GPS观察以及前进和反向建模，使用三维，几何逼真的俯冲俯冲/前核有限元元素网格，该团队正在解决以下重要问题：（1）由于弯曲型的弯曲范围是否有效地转移到了前进的情况下，是否有效地转移了弯曲的弯曲和偏离的变化。在前臂滑动的前缘的地壳增厚上受到青睐； （2）为什么预期地壳增厚的两个前臂片之间的弯曲是被地形凹陷（Fonseca的海湾）所占据的； （3）两个前臂的运动是通过弧线平行滑动断层，书架断层或两者的某种组合来容纳的； （4）萨尔瓦多火山弧内舷内的西方伸展特征是否也延伸到前臂，如果是的话，这种拉伸与伸展的相互作用并影响了滑片的运输。 Finally, a series of modeling experiments are being conducted to better understand the kinematics and dynamics of the subduction/forearc wedge system, using a three-dimensional finite element model and a series of plausible boundary conditions, including dip-slip tractions at the base of the wedge, variable resistance to slip along the subduction interface and forearc faults, and varying degrees of buttressing at the leading edge of the wedge.通过通过GPS和基于现场的结构工作研究中美洲的积极变形的综合方法，正在建立理解该地区地震周期的概念和运动学框架。自1900年以来，在该地区的许多中等大小地震中，已经发生了数万死亡。知识和技术转移到萨尔瓦多和尼加拉瓜的合作者在两个国家的未来地震危害研究中都显着受益。研究生正在接受结构地质学和高精度测量学研究地震周期的培训。