Toward Dynamic Models of Contemporary Plate Boundary Deformation with Application to the Taiwan Collision Zone

当代板块边界变形动态模型及其在台湾碰撞带中的应用

• 批准号: 0609620
• 负责人: Kaj Johnson
• 金额: --
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0609620&HistoricalAwards=false
• 关键词: Toward; Dynamic; Models; Contemporary; Plate

The recent catastrophic earthquakes in Sumatra and Pakistan underscore the importance of developing techniques to identify potential large seismic sources and gaining an improved understanding of plate-boundary deformation processes. Crustal deformation models constrained by geodetic, seismic, paleoseismic, and geomorphic data are the appropriate tools for probing into the physics of plate-boundary deformation. The purpose of this research is to develop dynamic models of plate-boundary deformation that incorporate GPS measurements of crustal motions with a wide variety of geologic and geophysical data sets from the Taiwan arc-continent collision zone, one of the most densely instrumented, yet poorly understood, plate boundaries. The models are dynamic in the sense that slip on faults is governed by an assumed constitutive law that relates stresses in the lithosphere to fault slip. The models being developed in this research are an extension of related kinematic models in which slip on faults is prescribed based solely on the motions of lithospheric blocks, without regard to the driving forces. The overarching questions that motivate this work are directed toward an improved understanding of factors that control the spatial and temporal distribution of lithospheric deformation in Taiwan and other plate-boundary settings: 1) How is the rapid arc-continent convergence in Taiwan distributed among the active faults and folds? 2) What role do creeping and locked fault segments play in distributing this deformation?, 3) What role does fault geometry play in distributing the deformation?, 3) Where are future earthquakes likely to occur?, and 4) How can the various disparate data sets be integrated into a comprehensive 3D model of this ongoing deformation process? In particular, the research aims to integrate the dynamic model with various data sets to obtain estimates of fault slip rates in Taiwan and determine the spatial distribution of locked sections of active faults that are likely to rupture in future earthquakes. Model predictions of fault slip rates from GPS data are constrained by paleoseismic, geologic, and geomorphic estimates of long-term slip rates. Active fault geometry and locations of creeping and locked fault patches are constrained by relocated seismicity, distributions of earthquake focal mechanisms, and locations of small repeating earthquakes. Seismic tomography constrains crustal geometry and rheology.

最近在苏门答腊岛和巴基斯坦发生的灾难性地震强调了开发技术以查明潜在的大震源和增进对板块边界变形过程的了解的重要性。受大地测量、地震、古地震和地貌数据约束的地壳形变模型是探讨板块边界形变物理的合适工具。这项研究的目的是建立板块边界变形的动力学模型，将地壳运动的GPS测量与来自台湾弧陆碰撞带的各种地质和地球物理数据集结合起来，台湾弧-大陆碰撞带是仪器设备最密集但了解最少的板块边界之一。这些模型是动态的，因为断层上的滑动是由假设的本构定律控制的，该定律将岩石圈中的应力与断层滑动联系起来。这项研究中开发的模型是相关运动学模型的扩展，在这些模型中，断层上的滑动完全基于岩石圈块体的运动来确定，而不考虑驱动力。推动这项工作的主要问题是为了更好地理解控制台湾和其他板块边界地区岩石圈形变的时空分布的因素：1)台湾快速的弧陆会聚是如何在活动断裂和褶皱之间分布的？2)蠕动和锁定的断裂段在分布这种形变方面扮演了什么角色？3)断层几何形状在分布形变中扮演了什么角色？3)未来地震可能发生在哪里？以及4)如何将各种不同的数据集整合到这个正在进行的形变过程的综合3D模型中？特别是，这项研究的目的是将动态模型与各种数据集相结合，以获得对台湾断层滑移率的估计，并确定未来地震中可能破裂的活动断层锁定区段的空间分布。从GPS数据对断层滑动速率的模型预测受到对长期滑动速率的古地震、地质和地貌估计的限制。活动断层的几何形状和爬行和锁定断层的位置受到重新定位的地震活动、震源机制的分布和小规模重复地震的位置的限制。地震层析成像限制了地壳几何和流变学。