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

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震相来研究断裂带的地下结构：面波、体波、断裂带首波和断裂带陷波。通过利用记录的地震波场的较大部分，我们应该能够更好地分辨出波敏感的断裂带结构。我们使用一种基于伴随的层析反演技术，该技术依赖于高精度的三维地震波场模拟。这项研究包括以下三个部分：(1)在真实、复杂的三维断裂带模型中模拟合成地震记录，包括澄清产生所记录的头部和捕获波的观测特征的几何和材料变化的允许范围；(2)各种断裂带、体相和地表相对深部关键断裂带结构的体积敏感性分析；(3)Parkfield附近的San Andreas断层和San Jacinto断裂带不同部分的迭代伴随层析成像。对地震成核和破裂的物理环境的详细描述尚未实现。通过模拟对断裂带结构特别敏感的地震波，我们可以成像断裂带的地下结构。断层带成像的基本困难来自于其多尺度和强烈的构造变化，这些变化在地表和井内都很明显。通过使用精确的地震波传播模型，这项研究将提供记录数据所提供的最详细的断裂带结构描述。该项目专注于南加州的两个具有社会意义的断裂带。