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

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的，该研究工作的重点是在受控实验室条件下产生类似地震破裂的独特实验能力的进步。这个实验的特点是一个模型标本的界面模拟了地球上的自然断层。地壳。在模拟自然构造应力的施加压缩载荷的作用下，该组件通过静摩擦保持在一起。在试样内部引起的地震滑动导致沿断层传播的动态破裂，同时将地震波能量辐射到试样体内。仪器完备的实验室地震装置为研究复杂的地震现象提供了多功能的测试能力，如动态摩擦滑动、辐射地面运动、超剪切破裂和与复杂几何形状相关的动态破裂过程。在这笔拨款的支持下，工作的目标是开发和整合新的光学诊断，以精确测量这些实验中产生的粒子（地面）运动和相关应力场。整套光学诊断技术，如时间分辨干涉测量技术和高速数字摄影技术，除了辐射波场的全场表征外，还可以在一系列固定测量站进行高分辨率的应力和地面运动测量。总的来说，这些先进的实验室地震能力将允许对许多与地震学相关的长期存在的问题进行实验研究。研究结果将有助于弥合从实地获得的经验证据和对地震学有明显潜在好处的计算预测之间的差距。本研究的跨学科性质必然涉及到在各个学科中为许多目标分配优先级。特别是，在新实验的设计中体现了两个主要特征。首先，实验设计的目的是尽可能与他们所模拟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审查的现象产生明确的理解。提出的实验调查将处理和解决有关地震动力学的许多争议。这些基准实验的新发现将为建模者提供数据，这些数据将有助于验证各种运动学反演和动态破裂模型。这项研究旨在促进地震学和地震减灾之间的联系。下面的列表概述了建议的仪器增强，并概述了该建议在地震学的一些目标领域的更广泛的影响。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分析和数值模型的基准。同时测量地震动、滑移速度和传播破裂局部附近的全应力张量。结合在多个站点获得的高时间分辨率、逐点测量数据，以及空间分辨率的全场测量数据，研究非均匀滑动情况下的动态摩擦规律。利用高度控制的实验室环境，清楚地识别出亚瑞利断裂或超剪切断裂以及它们的速度和模式转变（脉冲型与裂纹型）所导致的辐射地面运动的主要特征和区别特征。研究超剪切事件对地震灾害的未知影响。通过复杂的几何形状研究破裂传播，并表征此类事件产生的强地面运动的高频内容。引入复杂和更现实的断层几何基准，测量最终滑动分布，以及时间分辨的多站记录，以验证运动学反演代码。

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.