Collaborative Research: Laboratory Study of the Mechanics and Physical Properties of the Active San Andreas Fault Zone From Phase III SAFOD Cores

合作研究：圣安地列斯活动断层带 III 期 SAFOD 岩心力学和物理性质的实验室研究

• 批准号: 0746149
• 负责人: Harold Tobin
• 金额: $ 9.69万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0746149&HistoricalAwards=false
• 关键词: Collaborative; Research; Laboratory; Study; Mechanics

Collaborative Research: Laboratory Study of the Mechanics and Physical Properties of the active San Andreas Fault zone from Phase III SAFOD coresDemian Saffer & Chris Marone, The Pennsylvania State UniversityHarold Tobin, The University of Wisconsin-MadisonOne of the primary goals of EarthScope, and the SAFOD experiment in particular, is to improve our understanding of faulting and earthquakes. Through sampling, down-hole measurements, and long-term monitoring, the SAFOD experiment will provide data to test hypotheses regarding long-term fault strength, earthquake nucleation and recurrence, and the role of fluids in faulting. Laboratory investigations of the frictional, elastic, and fluid transport properties of fault and wall rocks are a key part of achieving these goals. This collaborative project focuses on laboratory measurements of frictional, permeability, and elastic properties for both the active San Andreas Fault (SAF) zone sampled during SAFOD Phase 3 drilling, and for outcrop samples of lithologies that represent the host rock for the cored SAF material. The PI's are applying their experimental results to understand processes governing (1) the strength, sliding stability, and healing of major faults, (2) the hydraulic behavior of faults - both locally as related to long-term and dynamic weakening mechanisms and regionally as elements within crustal scale fluid flow systems, and (3) the rock properties and in situ conditions that cause signatures observed remotely by geophysical surveys. The friction and permeability measurements are being carried out in the Penn State rock and sediment mechanics laboratory, under a range of stress conditions in both a uniaxial loading system and a true triaxial system. The friction experiments include measurements of shear strength and rate-and state parameters relevant to sliding stability, on both powdered gouge and intact "wafers" of material. Permeability measurements are being conducted using flow-through and transient techniques under a range of uniaxial strain and triaxial stress boundary conditions. The elastic property component of the study includes ultrasonic wave velocity and attenuation measurements on intact mini-cores conducted in a pressure vessel at the University of Wisconsin-Madison, and measurements on shearing layers as part of friction experiments at Penn State. Ultimately, this ongoing research will provide experimental constraints on rock properties for the San Andreas Fault system that relate to its mechanical strength, sliding stability, potential role as a barrier to regional fluid flow, and the interpretation of in situ conditions from geophysical data.

合作研究：来自第三阶段 SAFOD 核心的活动圣安德烈亚斯断层带的力学和物理特性的实验室研究德米安·萨弗 (Demian Saffer) 和克里斯·马龙 (Chris Marone)，宾夕法尼亚州立大学哈罗德·托宾 (Harold Tobin)，威斯康星大学麦迪逊分校 EarthScope 和 SAFOD 的主要目标之一特别是实验，是为了提高我们对断层和地震的理解。通过采样、井下测量和长期监测，SAFOD 实验将提供数据来检验有关长期断层强度、地震成核和复发以及流体在断层作用中的作用的假设。对断层和围岩的摩擦、弹性和流体传输特性的实验室研究是实现这些目标的关键部分。该合作项目的重点是对 SAFOD 第 3 阶段钻探期间采样的活动圣安德烈亚斯断层 (SAF) 区域以及代表取芯 SAF 材料主岩的岩性露头样本的摩擦、渗透性和弹性特性进行实验室测量。 PI 正在应用他们的实验结果来了解控制 (1) 主要断层的强度、滑动稳定性和愈合，(2) 断层的水力行为的过程 - 局部与长期和动态弱化机制相关，以及区域性地壳尺度流体流动系统内的元素，以及（3）岩石特性和导致通过地球物理调查远程观察到的特征的原位条件。摩擦力和渗透率测量是在宾夕法尼亚州立大学岩石和沉积物力学实验室在单轴加载系统和真正的三轴系统的一系列应力条件下进行的。摩擦实验包括在粉状凿岩和完整的材料“晶片”上测量剪切强度以及与滑动稳定性相关的速率和状态参数。渗透率测量是在一系列单轴应变和三轴应力边界条件下使用流通和瞬态技术进行的。该研究的弹性特性部分包括在威斯康星大学麦迪逊分校的压力容器中对完整微型核心进行的超声波速度和衰减测量，以及作为宾夕法尼亚州立大学摩擦实验一部分的剪切层测量。最终，这项正在进行的研究将为圣安德烈亚斯断层系统的岩石特性提供实验约束，这些特性涉及其机械强度、滑动稳定性、作为区域流体流动屏障的潜在作用，以及根据地球物理数据对现场条件的解释。