Laboratory Earthquakes: Characterization of Ground Motion and Stress States in Complex Rupture Scenarios Using High Resolution Optical Diagnostics

实验室地震：使用高分辨率光学诊断表征复杂破裂场景中的地面运动和应力状态

• 批准号: 0911723
• 负责人: Ares Rosakis
• 金额: $ 40.5万
• 依托单位: California Institute of Technology
• 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: 2009-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911723&HistoricalAwards=false
• 关键词: Laboratory; Earthquakes; Characterization; Ground; Motion

This award is funded under the American Recovery and Reinvestment Act 2009 (Public Law 111-5) The thrust of this research effort will focus on the advancement of a unique experimental capability for generating earthquake-like ruptures under controlled laboratory conditions. The experiment features a model specimen with an interface that simulates a natural fault in the Earth?s crust. The assembly is held together by static friction under the action of a an applied compressive load which mimics natural tectonic stresses. Seismic slip induced within the specimen results in a dynamic rupture that propagates along the fault while radiating seismic wave energy into the body of the specimen. A well instrumented laboratory earthquake setup provides a versatile testing capability for investigating complex seismological phenomena such as dynamic frictional sliding, radiated ground motion, supershear ruptures, and dynamic rupture processes associated with complex geometries. Work under the support of this grant will target the development and integration of new optical diagnostics for the precise measurement of the resulting particle (ground) motion and associated stress fields in these experiments. A full suite of optical diagnostics, such as time resolved interferometry techniques and high speed digital photography will enable high resolution measurements of stress and ground motion at an array of fixed measurement stations in addition to full field characterization of radiated wave fields. Collectively, these advanced laboratory earthquake capabilities will permit the experimental investigation of numerous long standing problems of seismological relevance. Research findings will help to bridge the gap between empirical evidence obtained from the field and computational predictions with obvious potential benefits to seismology. The interdisciplinary nature of this research necessarily involves assigning priorities to the many goals within individual disciplines. In particular, two main characteristics are reflected in the design of the new experiments. Firstly, the experimental design is intended to be as relevant as possible to the geophysical systems that they model. Secondly, the experimental configuration is kept as basic as possible so that real-time data collection and analyses can produce, unequivocal, understanding of the phenomena under scrutiny. The proposed experimental investigations will address and resolve many controversies regarding the dynamics of earthquakes. New findings from such benchmark experiments will provide data to modelers that will subsequently aid in the validation of various kinematic inversion and dynamic rupture models. The research is designed to facilitate connections in seismology and earthquake hazard mitigation. The following list provides an overview of the proposed instrumentation enhancements and outlines the broader impacts of this proposal in a number of targeted areas of seismology. Primary research objectives are: Setting up highly instrumented Laboratory Earthquake experiments especially designed to study a variety of rupture phenomena and to serve as benchmarks for the validation of analytical and numerical models of dynamic earthquake rupture. Simultaneously measuring ground motion, slip velocity, and the complete stress tensor in the local vicinity of propagating ruptures. Combining high temporal resolution, point-wise measurements, obtained at multiple stations, along with spatially resolved full-field measurements to study dynamic frictional laws in the presence of non-uniform sliding. Utilizing the highly controlled laboratory environment to clearly identify the dominant and distinguishing signatures of radiated ground motion resulting from either sub-Rayleigh or supershear ruptures and from their transitions in both speed and mode (pulse-like vs. crack-like). Investigating the unknown effect of supershear events on seismic hazards. Studying rupture propagation through complex geometries and characterize the high frequency content of the strong ground motion from such events. Introducing complex and more realistic fault geometry benchmarks and measuring final slip distribution, in addition to time-resolved multi-station recordings, in order to validate kinematic inversion codes.

该奖项由《2009 年美国复苏和再投资法案》（公法 111-5）资助。这项研究工作的主旨将集中于提高在受控实验室条件下产生类地震破裂的独特实验能力。该实验的特点是模型样本具有模拟地壳自然断层的界面。该组件在模拟自然构造应力的压缩载荷作用下通过静摩擦固定在一起。样本内引起的地震滑动导致动态破裂，该破裂沿着断层传播，同时将地震波能量辐射到样本体内。仪器齐全的实验室地震装置提供了多功能的测试能力，用于研究复杂的地震现象，例如动态摩擦滑动、辐射地震动、超剪切破裂以及与复杂几何形状相关的动态破裂过程。在这笔赠款支持下的工作将致力于开发和集成新的光学诊断技术，以精确测量这些实验中产生的粒子（地面）运动和相关的应力场。除了辐射波场的全场表征之外，一整套光学诊断技术（例如时间分辨干涉测量技术和高速数字摄影）将能够在一系列固定测量站上对应力和地面运动进行高分辨率测量。总的来说，这些先进的实验室地震能力将允许对许多长期存在的地震相关问题进行实验研究。研究结果将有助于弥合从现场获得的经验证据与计算预测之间的差距，对地震学具有明显的潜在好处。这项研究的跨学科性质必然涉及到为各个学科内的许多目标分配优先级。特别是，新实验的设计体现了两个主要特征。首先，实验设计旨在尽可能与他们建模的地球物理系统相关。其次，实验配置尽可能保持基本，以便实时数据收集和分析可以对所观察的现象产生明确的理解。拟议的实验研究将解决和解决有关地震动力学的许多争议。此类基准实验的新发现将为建模者提供数据，这些数据随后将有助于验证各种运动学反演和动态破裂模型。该研究旨在促进地震学和地震减灾之间的联系。以下列表概述了拟议的仪器增强功能，并概述了该提案在地震学许多目标领域的更广泛影响。 主要研究目标是： 建立高度仪器化的实验室地震实验，专门用于研究各种破裂现象，并作为验证动态地震破裂的分析和数值模型的基准。同时测量传播破裂局部附近的地面运动、滑移速度和完整应力张量。结合在多个站点获得的高时间分辨率、逐点测量以及空间分辨全场测量，以研究存在非均匀滑动的动态摩擦定律。利用高度受控的实验室环境，清楚地识别由亚瑞利或超剪切破裂及其速度和模式（脉冲状与裂纹状）转变引起的辐射地面运动的主要和显着特征。研究超剪切事件对地震灾害的未知影响。研究复杂几何形状中的破裂传播，并表征此类事件产生的强烈地面运动的高频内容。除了时间分辨多站记录之外，还引入复杂且更现实的断层几何基准并测量最终滑移分布，以验证运动反演代码。