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Observations of Fault Growth Under Elevated Fluid Pressure Using Dynamic Microtomography

使用动态显微断层扫描观察高流体压力下的断层生长

基本信息

批准号：
1761912
负责人：
Wen-Lu Zhu
金额：
$ 35.86万
依托单位：
University of Maryland, College Park
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-06-01 至 2023-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1761912&HistoricalAwards=false
关键词：
Observations Fault Growth Under Elevated

项目摘要

Sudden motions of a tectonic fault such as the San Andreas fault cause earthquakes. Better seismic risk assessment requires quantitative knowledge of fault distribution and propagation. The discovery of slow slip events, those that occur over hours to months instead of seconds, at convergent plate boundaries, like in the Pacific Northwest, provides new opportunities to study the mechanics of earthquakes and other fault instabilities. Seismic observations link slow slip events to high fluid pressure within the fault zones but how this works mechanically is still unclear. Recent studies in the lab that emulate these conditions show that increasing pore pressure slow down fault growth. This project looks to advance these experiments to improve our understanding of the mechanics of slow faulting under high pore pressure. The work has broader impacts on our understanding of seismic hazards at coastal plate boundaries as well as other areas that see this type of complex faulting. The researcher will also provide a research experience for an undergraduate, and conduct outreach to a nearby high school to bring students into a scientific lab. The project supports a postdoctoral fellow and a graduate student.The researchers hypothesize that dilatant hardening at crack tip can cause deformation to migrate, which results in delocalized fracturing and slow fault propagation. To test this hypothesis, the work enables deformation experiments using an X-ray transparent deformation apparatus to record the real-time fault growth. The state-of-the-art dynamic microtomography imaging will elucidate the fault nucleation process and growth pattern in a deforming rock at in-situ conditions. They will also incorporate dilatancy hardening into the damage model to simulate the effect of pore pressure on fault propagation. Comparison of the 3-D microstructure generated by numerical simulations and the time-lapse tomography images will provide new insights into deformation mechanisms. The goal is to build a better understanding of the mechanics of slow fault growth, and thus provide the critical link between the geophysical observations and the stress states of a megathrust fault during the interseismic period of an earthquake cycle.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

像圣安德烈亚斯断层这样的构造断层的突然运动会引起地震。更好的地震风险评估需要断层分布和传播的定量知识。缓慢滑动事件的发现，那些发生在几个小时到几个月而不是几秒钟，在会聚的板块边界，如在太平洋西北部，提供了新的机会来研究地震和其他断层不稳定性的机制。地震观测将缓慢滑动事件与断层带内的高流体压力联系起来，但这是如何机械地工作的仍然不清楚。最近在实验室中模拟这些条件的研究表明，增加孔隙压力会减缓断层的生长。该项目旨在推进这些实验，以提高我们对高孔隙压力下缓慢断层力学的理解。这项工作对我们理解沿海板块边界以及其他看到这种复杂断层的地区的地震危险具有更广泛的影响。研究人员还将为本科生提供研究经验，并与附近的高中进行外联，将学生带入科学实验室。该项目支持一名博士后和一名研究生。研究人员假设裂纹尖端的胀流硬化会导致变形迁移，从而导致离域破裂和断层传播缓慢。为了验证这一假设，这项工作使变形实验使用X射线透明变形装置记录实时断层生长。最先进的动态显微层析成像将阐明断层成核过程和增长模式在变形岩石在原位条件下。他们还将把渗透硬化纳入损伤模型，以模拟孔隙压力对断层传播的影响。数值模拟和时间推移断层扫描图像产生的3-D微观结构的比较将提供新的见解变形机制。其目标是建立一个更好的理解缓慢断层增长的机制，从而提供地球物理观测和地震周期的地震间隔期间的巨型逆冲断层的应力状态之间的关键环节。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

项目成果

期刊论文数量（11）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Dynamic In Situ Three-Dimensional Imaging and Digital Volume Correlation Analysis to Quantify Strain Localization and Fracture Coalescence in Sandstone

DOI：
10.1007/s00024-018-2003-x
发表时间：
2018-10
期刊：
Pure and Applied Geophysics
影响因子：
2
作者：
François Renard;J. McBeck;B. Cordonnier;Xiaojiao Zheng;Neelima Kandula;Jesus R. Sanchez;M. Kobchenko-M.-Kobchen
通讯作者：
François Renard;J. McBeck;B. Cordonnier;Xiaojiao Zheng;Neelima Kandula;Jesus R. Sanchez;M. Kobchenko-M.-Kobchen

The competition between fracture nucleation, propagation, and coalescence in dry and water-saturated crystalline rock