Experimental Investigation of Mechanisms for High Pore Fluid Pressure Associated Slow Faulting

高孔隙流体压力伴慢断层机理的实验研究

• 批准号: 2218314
• 负责人: Wen-Lu Zhu
• 金额: $ 39.83万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2218314&HistoricalAwards=false
• 关键词: Experimental; Investigation; Mechanisms; Pore; Fluid; Experimental; Investigation; Mechanisms; Pore; Fluid

Slow slip at various subduction zones provides a new opportunity to study the state of megathrust faults in between great earthquakes. Elevated pore fluid pressure in the subduction zone is often detected in regions where slow slip events occur, but it is not well understood how this high pore pressure is actually linked to the slow slip. This project explores this link between fluids and the mechanisms for slow slip through laboratory experiments on how rocks deform. The project will use a new imaging technique, dynamic microtomography, that helps image the interior of a rock sample as it is pressed to the point of failure. These experiments can be conducted at different levels of pore pressure and at different and variable speeds to explore the range of conditions that can lead a fault to move from fast slip to steady slow slip.Recent experimental studies show that high pore fluid pressure can stabilize both fault propagation in intact rocks and decelerates frictional slip in rocks with an existing fault. Dilatant hardening under undrained conditions is thought to be responsible for these observed stabilization effects. Preliminary experimental data show that high pore fluid pressure can also impede fault growth under nominally drained conditions. This project is a systematic set of fracture and friction experiments to understand the role of elevated pore fluid pressure on stabilizing faulting and frictional slip. The goal is to 1) characterize the real-time microstructure evolution using dynamic microtomography. This will result in a quantitative assessment of the spatio-temporal distributions of permeability, porosity, and pore shape, thus better constraints of the drainage conditions during brittle failure; 2) elucidate the role of dilatant hardening in the transition from stick-slip events to slow slip events along a pre-existing fault. The researchers will use different gouge materials to produce different drainage conditions and investigate the mechanical link between high pore fluid pressure and slow slip behaviors; 3) identify diagnostic characteristics of fault geometry and off-fault damage associated with slow faulting. The findings of this study will lead to a better understanding of different instabilities and the mechanical processes responsible for them.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.

各种俯冲带的慢滑动为研究大地震之间的大型断层状态提供了新的机会。在发生缓慢的滑动事件的区域，经常检测到俯冲带的孔隙流体压力升高，但尚不清楚这种高孔压力实际上与慢速滑移有关。该项目探讨了流体和通过实验室实验慢速滑移的机制之间的这种联系，涉及岩石如何变形。该项目将使用一种新的成像技术，动态的微传输学，可帮助对岩石样品的内部进行对象，因为它被压缩到故障点。这些实验可以在不同水平的孔隙压力和不同和可变速度下进行，以探索可能导致断层从快速滑移到稳定缓慢滑动的条件范围。重新实验研究表明，高孔隙流体压力可以稳定完整岩石中的故障且具有现有故障的岩石中的摩擦下裂纹。在不排水条件下，膨胀的硬化被认为​​是这些观察到的稳定作用的原因。初步实验数据表明，高孔隙流体压力也可能阻碍名义上排水条件下的断层生长。该项目是一组系统的断裂和摩擦实验，以了解升高的孔隙流体压力对稳定断层和摩擦滑动的作用。目标是1）使用动态微传输术表征实时微观结构演化。这将导致对渗透率，孔隙率和孔形形状的时空分布进行定量评估，从而在脆性失败期间对排水条件的更好约束； 2）阐明膨胀剂在从粘性事件的过渡中，沿着预先存在的断层慢慢滑移事件的过渡。研究人员将使用不同的岩石材料产生不同的排水条件，并研究高孔隙流体压力和缓慢滑动行为之间的机械联系； 3）确定故障几何形状和与慢性断层相关的OFF损伤的诊断特征。这项研究的结果将使人们对不同的不稳定性和机械过程有更好的了解。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响评估标准来通过评估来支持的。