Microstructural analyses of gouge from the San Andreas Fault Observatory at Depth (SAFOD) borehole in relation to brittle fault mechanics: A collaborative study

0545472Hadizadeh本研究使用圣安德烈亚斯断层观测站（SAFOD）第二和第三阶段岩心样本的显微结构特征来测试特定的断层泥演化模型。这些工作模型是基于大量以前的现场和实验研究的折返断层岩，模拟断层泥实验，断层泥变形的数值模拟以及脆性岩石变形和岩石摩擦的理论考虑。数据收集、观察、分析和知识管理由美国（路易斯维尔大学和格鲁吉亚州立大学）、挪威（PGP，奥斯陆大学）和意大利（帕多瓦大学）的校园团队合作进行。正在调查的主要问题如下。当连续粉碎倾向于减小颗粒尺寸时，凿痕是否经历循环的机械行为？如果是这样，这些过程是如何反映在断层系统的长期地震行为？2.岩槽中颗粒尺寸减小和应变局部化的物理学原理是什么？3.除脆性断裂外，还有哪些机制起着关键作用？4.断层泥颗粒压裂所用地震能量的比例是多少？所应用的方法包括使用电子显微镜、分析技术、定制图像分析和数值模拟以及对SAFOD断层泥样品进行的亚地震速度摩擦滑动实验进行定量微观结构分析。 研究结果可在万维网上查阅，这些结果来自专门为此项目开发和实施的几个综合数据库和领域本体。研究结果也在科学会议和期刊上介绍和发表。这些数据库和知识库设在地球科学网络网格的一个节点（www.geongrid.org）上，也可从地球范围的网页上查阅。

0545472HadizadehThis study uses microstructural characteristics of the San Andreas Fault Observatory at Depth (SAFOD) phase II and III core samples to test specific fault gouge evolution models. These working models are based on a large number of previous field and experimental studies of exhumed fault rocks, simulated fault gouge experiments, and numerical simulations of gouge deformation as well as theoretical considerations of brittle rock deformation and rock friction. The data collection, observations, analyses, and knowledge management are carried out by collaborative teamwork from campuses in the U.S.A. (University of Louisville and Georgia State University), Norway (PGP, University of Oslo), and Italy (University of Padova). The primary questions being investigated are as follows.1. Do gouges undergo a cyclic mechanical behavior while continuous comminution tends to reduce the particle size? If so, how are these processes reflected in the long-term seismic behavior of fault systems? 2. What is the physics of particle size reduction and strain localization in rock gouges? 3. What mechanisms in addition to brittle fracture play a critical role? 4. What proportion of seismic energy is used in gouge particle fracture? The applied methodologies include quantitative microstructural analysis using electron microscopy, analytical techniques, customized image analysis and numerical simulations as well as sub-seismic velocity frictional sliding experiments on the SAFOD gouge samples. The results are available on the Worldwide Web, from several integrated databases and domain ontologies that are being developed and implemented specifically for this project. Results are also being presented and published in scientific conferences and periodicals. These databases and knowledge bases, hosted on a node of the GEON (Geosciences Network) grid (www.geongrid.org) are also accessible from the EarthScope webpage.