Collaborative Research: Adjoint tomography of fault zone environments

合作研究：断层带环境的伴随断层扫描

• 批准号: 1314875
• 负责人: Yehuda Ben-Zion
• 金额: $ 7.43万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1314875&HistoricalAwards=false
• 关键词: Collaborative; Research; Adjoint; tomography; fault; Collaborative; Research; Adjoint; tomography; fault

We are investigating the subsurface structure of fault zones using a variety of seismic phases: surface waves, body waves, fault zone head waves, and fault zone trapped waves. By using a larger portion of the recorded seismic wavefield, we should be able to better resolve the fault zone structures to which the waves are sensitive. We use an adjoint-based tomographic inversion technique that relies on highly accurate, three-dimensional seismic wavefield simulations. The study has the following three components: (1) simulations of synthetic seismograms in realistic, complex 3D fault zone models, including clarifying the allowable ranges of geometrical and material variations that produce the observed characteristics of recorded head and trapped waves; (2) analysis of volumetric sensitivities of various fault zone, body, and surface phases to key fault zone structures at depth; (3) iterative adjoint tomographic inversions for the structures of the San Andreas fault near Parkfield and different sections of the San Jacinto fault zone.Large damaging earthquakes originate on faults kilometers below Earth's surface. A detailed characterization of the physical setting where earthquakes nucleate and rupture has not yet been achieved. By modeling seismic waves that are particularly sensitive to the structures of fault zones, we can image the subsurface structure of fault zones. The basic difficulty in imaging fault zones stems from their multi-scale and strong variations in structure, which are evident at the surface and within boreholes. By using accurate seismic wave propagation models, the study will provide the most detailed description of fault zone structure afforded by the recorded data. The project focuses on two societally relevant fault zones in southern California.

我们正在使用各种地震阶段研究断层区域的地下结构：表面波，体波，断层区头波和断层区捕获波。通过使用记录的地震波场的较大部分，我们应该能够更好地解析波敏感的断层区结构。我们使用基于伴随的层析成像反演技术，该技术依赖于高度准确的三维地震波场模拟。该研究具有以下三个组成部分：（1）在现实的，复杂的3D断层区模型中的合成地震图的模拟，包括阐明允许的几何和材料变化的允许范围，这些变化产生了记录的头部和捕获波的观察到的特征； （2）分析各种断层区，身体和表面相对于深度关键断层区结构的体积敏感性； （3）迭代的伴奏层析成像倒置在帕克菲尔德附近的圣安德烈亚斯断层的结构以及圣哈辛托断层区的不同部分。极度破坏地震源于地面表面以下的断层。尚未实现地震核和破裂的物理环境的详细表征。通过建模对断层区结构特别敏感的地震波，我们可以对断层区域的地下结构进行成像。成像故障区域的基本困难源于它们的多尺度和结构上的较强变化，这些变化在表面和井眼内是显而易见的。通过使用准确的地震波传播模型，该研究将提供记录数据提供的断层区结构的最详细说明。该项目着重于南加州两个社会相关的断层区。