Beyond elastic rebound: extracting permanent strain from interseismic deformation

超越弹性回弹：从震间变形中提取永久应变

• 批准号: 1520266
• 负责人: Kaj Johnson
• 金额: $ 12万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1520266&HistoricalAwards=false
• 关键词: Beyond; elastic; rebound; extracting; permanent

One of the main uses of GPS data in studying the boundaries of tectonic plates is to understand current rates for fault movements and understand how faults interact. This kind of understanding can all feed into a better assessment of earthquake hazards because it helps us better understand the longer term behavior of fault systems. The researchers in the project will try to reconcile two kinds of models, those that characterize single faults with those that look at long-term evolution of a full plate boundary. The results of this work have important implications for how fast plate boundaries are moving and how the ground around faults deforms over time. The work will use two examples, on in Taiwan, and the other in Southern California. Comparing and contrasting the two areas will improve overall understanding of earthquakes processes.The purpose of the proposed research is to develop dynamic models of geodetic data that extend traditional elastic models to include permanent deformation. The approach is to develop viscoelastic-plastic boundary element models in which the deforming crust is loaded by far-field stresses and faults slip and the surrounding crust deforms in response to the loads. They will employ geodetic data, stress state inferred from focal mechanism data, and geologic and thermochronologic data to constrain the deformation models. In Taiwan they will use the GPS-derived horizontal and vertical velocity fields, an island-wide leveling network, and stress orientations throughout the crust to address several key outstanding issues about the fault architecture responsible for mountain building processes in Taiwan. They will test several models of deep fault geometry and a proposed deep-seated underplating processfor uplifting the core of the mountain range. Model results will be compared with low-temperature thermochronology. In southern California the research will examine models of long-term deformation across the strike-slip fault system to determine the relative contributions of various pate-driving forces (plate boundary forces, gravitational potential energy, mantle drag) and compare predicted long-term fault slip rates with geologic slip rate estimates. They will focus on the important outstanding problem of the portion of deformation that occurs as off-fault inelastic yielding distribution through the crust versus deformation that is accommodated by slip on faults.

在研究构造板块边界时，GPS数据的主要用途之一是了解断层运动的当前速率以及断层如何相互作用。这种理解都有助于更好地评估地震的危险性，因为它有助于我们更好地了解断层系统的长期行为。该项目的研究人员将试图调和两种模型，一种是描述单个断层的模型，另一种是观察整个板块边界长期演化的模型。这项工作的结果对板块边界移动的速度以及断层周围的地面如何随时间变形具有重要意义。这项工作将使用两个例子，一个在台湾，另一个在南加州。比较和对比这两个区域将提高对地震过程的全面认识。提出的研究目的是发展动态模型的大地数据扩展传统的弹性模型，以包括永久变形。该方法是建立粘弹塑性边界元模型，其中变形地壳受到远场应力和断层滑动的载荷，周围地壳在载荷作用下发生变形。他们将利用大地测量数据、震源机制数据推断的应力状态以及地质和热年代学数据来约束变形模型。在台湾，他们将使用gps得到的水平和垂直速度场、全岛范围的水准网和整个地壳的应力方向来解决台湾造山过程中断层结构的几个关键突出问题。他们将测试几种深断层几何模型，以及一种被提议的隆起山脉核心的深层底板过程。模型结果将与低温热年代学进行比较。在南加州，该研究将检查走滑断层系统的长期变形模型，以确定各种驱动力量（板块边界力、重力势能、地幔阻力）的相对贡献，并将预测的长期断层滑动率与地质滑动率估计进行比较。他们将把重点放在重要的突出问题上，即发生在断层外的非弹性屈服分布的变形部分与断层上滑动所容纳的变形部分。