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Feedbacks between faulting and fluid flow throughout the seismic cycle: An experimental approach

整个地震周期中断层和流体流动之间的反馈：一种实验方法

基本信息

批准号：
NE/S000852/1
负责人：
Nicolas Brantut
金额：
$ 60.78万
依托单位：
University College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FS000852%2F1
关键词：
Feedbacks between faulting fluid flow

项目摘要

In the Earth's crust, fluids are ubiquitous in the pores and cracks present in rocks. In tectonically active areas, for instance along major crustal faults or plate boundaries, rocks deform, crack and fail, which modifies the pore space by either compaction (for instance, collapse of open pores due to grain crushing) or dilation (generation and propagation of new open cracks). These changes in pore space generate local fluid pressure variations and also have a great impact on the ability of fluids to move through rocks and faults. Interestingly, the fluid pressure and fluid flow patterns also have an impact on the deformation of rocks, therefore forming complex feedbacks that determine the overall strength of faults and the long-term tectonics of the Earth's crust. Our understanding of crustal fault mechanics therefore relies crucially on our knowledge of the spatio-temporal distribution of pore pressure in the crust.Our quantitative understanding of the feedback processes between deformation, fluid pressure and fluid flow in rocks is currently limited by our ability to measure in-situ rock properties, which are required for large scale model predictions. One of the key problem limiting our understanding is that rock deformation and fluid pressure and flow are coupled through large but very local porosity changes occurring prior to, during and after brittle failure.The goal of the proposed research is, therefore, to unlock this knowledge gap by conducting innovative laboratory experiments that make use of an array of a newly developed type of fluid pressure transducer capable of monitoring local and rapid changes in pressure throughout deformation. By positioning a 3D array of such transducers around laboratory rock samples, we will monitor (1) spatio-temporal localisation of dila- tancy/compaction during quasi-static and dynamic rupture, and (2) the development of heterogeneity and anisotropy in fluid transport properties. Ultimately, our experimental results will provide the key to the time-evolution of fault zone physical properties that are currently unavailable, but which are essential to fully evaluate the role of pore fluid pressure during deformation and faulting in the crust.

在地壳中，流体在岩石的孔隙和裂缝中无处不在。在构造活动区，例如沿着主要地壳断层或板块边界，岩石变形、破裂和破坏，这通过压实（例如，由于颗粒破碎而导致的开放孔隙的塌陷）或扩张（新的开放裂缝的产生和扩展）来改变孔隙空间。孔隙空间的这些变化产生局部流体压力变化，并且对流体通过岩石和断层的能力也有很大影响。有趣的是，流体压力和流体流动模式也对岩石的变形产生影响，从而形成复杂的反馈，决定断层的整体强度和地壳的长期构造。因此，我们对地壳断层力学的理解，关键依赖于我们的知识，时空分布的孔隙压力在地壳中，我们的变形，流体压力和流体流动之间的反馈过程的定量理解是目前有限的，我们的能力，测量原位岩石性质，这是需要大规模的模型预测。限制我们理解的关键问题之一是，岩石变形和流体压力和流动是通过发生在脆性破坏之前、期间和之后的大的但非常局部的孔隙度变化耦合的。通过进行创新的实验室实验，利用一系列新开发的流体压力传感器，在整个变形过程中压力的快速变化。通过在实验室岩石样品周围放置这种传感器的3D阵列，我们将监测（1）准静态和动态破裂期间扩张/压实的时空定位，以及（2）流体输运特性中的非均质性和各向异性的发展。最终，我们的实验结果将提供关键的时间演化的断层带物理性质，目前是不可用的，但这是必不可少的，以充分评估孔隙流体压力的作用，在地壳变形和断层。