Three-Dimensional Characterization of a Pseudotachylyte-Bearing Fault

含假速石断层的三维表征

• 批准号: 1145238
• 负责人: Phillip Resor
• 金额: $ 14.67万
• 依托单位: Wesleyan University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1145238&HistoricalAwards=false
• 关键词: Three; Dimensional; Characterization; Pseudotachylyte; Bearing

Fault slip is the dominant mode of deformation in the earth's upper crust. Faults within the crust, however, exhibit a range of behavior, from earthquake-generating stick-slip to aseismic creep. Laboratory-derived friction laws can explain this spectrum of fault behavior; however, the scaling of these laws to the conditions of natural earthquakes and the interpretation of the laws' physical meanings have proven to be formidable challenges. This research will bridge laboratory and earthquake scales by imaging the three dimensional geometry of pseudotachylyte-bearing faults. Pseudotachylytes, fault rocks formed from frictional melts, are generally considered the only unequivocal evidence ofearthquake slip velocities preserved in fault zones. The solidification of frictional melt "freezes in" earthquake source geometries; however, it also precludes the development of extensive fault surface exposures that have enabled previous studies of fault zone geometry. We have overcome this difficulty by imaging the intact 3D geometry of the fault using high-resolution X-ray computed tomography (CT). In this study we will use CT imagery of natural and experimental fault surfaces to quantify surface roughness, frictional contact area, and pseudotachylyte thickness and will thus determine the evolution of fault roughness with slip and estimate key frictional parameters at earthquake nucleation and propagation scales. The proposed project will improve the understanding of earthquakes and their effects, one of the primary goals of the National Earthquake Hazard Reduction Program. Furthermore, the project will establish a new collaboration between Wesleyan University, a primarily undergraduate institution in the US, and scientists from the Istituto Nazionale di Geofisica e Vulcanologia (INGV), a world-renowned research institute in Italy. Undergraduate students will play an integral role in the project, planting the seeds for future international and interdisciplinary research into the processes of brittle deformation in the earth's crust. These students will experience the full scope of the scientific process, from hypothesis generation, to study design, to presentation of results at professional meetings and in a written thesis. The project is being supported by the EAR Tectonics Program and the Office of International Science and Engineering's Global Venture Fund.

断层滑移是地球上皮中的主要变形模式。 然而，地壳内的断层表现出一系列行为，从地震产生粘粘到无性蠕变。 实验室衍生的摩擦法可以解释这种断层行为的范围；但是，这些法律将这些法律规模缩放到自然地震的条件以及对法律物理含义的解释已被证明是巨大的挑战。 这项研究将通过成像伪造胆囊断层的三维几何形状来弥合实验室和地震尺度。 伪造的岩石是由摩擦熔体形成的断层岩石，通常被认为是保存在断层区域中的唯一明确的earthquake滑动速度。 地震源几何形状中的摩尔融化“冻结”的固化；但是，这也排除了广泛的断层表面暴露的发展，这些暴露能够对断层区域的几何形状进行先前的研究。 我们通过使用高分辨率X射线计算机断层扫描（CT）成像故障的完整3D几何形状来克服这一困难。 在这项研究中，我们将使用自然和实验断层表面的CT图像来量化表面粗糙度，摩擦接触面积和假胆囊厚度，从而确定断层粗糙度的演变，并估算地震成核和传播量表的关键摩擦参数。 拟议的项目将改善对地震及其影响的理解，这是国家地震危害计划的主要目标之一。 此外，该项目将建立卫斯理大学（Wesleyan University）（美国主要是本科机构的卫斯理大学），以及来自伊斯蒂托图（Istituto）纳粹（Istituto Nazionale di Geofisica e vulcanologia（INGV））的科学家，这是一家意大利世界享誉世界的研究所。 本科生将在该项目中发挥不可或缺的作用，为未来的国际和跨学科研究播种，以研究地壳中脆性变形的过程。 这些学生将体验科学过程的全部范围，从假设产生到研究设计，再到在专业会议和书面论文中的成果的介绍。该项目得到了EAR Tectonics计划和国际科学与工程全球风险投资基金办公室的支持。