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Fault lubrication during earthquake propagation in thermally unstable rocks

热不稳定岩石地震传播过程中的断层润滑

基本信息

批准号：
NE/H021744/1
负责人：
Nicola De Paola
金额：
$ 72.23万
依托单位：
Durham University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH021744%2F1
关键词：
Fault lubrication during earthquake propagation

项目摘要

Three thermally activated mechanisms are considered to be of particular relevance during slip in thermally unstable rocks such as carbonates: 1) flash heating at highly stressed frictional micro-contacts (asperities); 2) thermal pressurization of heated fluids released and/or trapped in the slip zone; and 3) the lubrication effects of nanoparticles produced by thermally-induced chemical decomposition reactions (decarbonation). In order to investigate whether such chemical and physical reactions in carbonate fault zones can make faults extremely weak and favour the continued propagation of earthquake ruptures, we propose here a multidisciplinary research program where mechanical, mineralogical, microstructural, fluid flow properties and modelling data, obtained from both field and laboratory studies are integrated. Fieldwork studies will be carried out in carbonate rocks from the Italian Apennines to reconstruct the natural fault zone geometries, identify the different structural domains and their associated fault rock assemblages. The integration of field observations and microstructural/mineralogical analyses will provide important geological constraints in the analysis and interpretation of the dominant deformation processes observed in experimentally deformed samples. These results will be used to produce a new classification scheme for seismic fault rocks in carbonates, based on the identification and description of diagnostic associations of fault rocks and microstructures which are indicators of earthquake slip events. This classification will aid in the recognition of fossil earthquakes along exposed fault segments and, therefore, can be used to interpret records of palaeo-seismic faulting in other parts of the world, aiding in risk/hazard assessment. High velocity friction experiments will be performed on solid and granular carbonate rocks, sheared at speeds similar to that seen in large earthquakes (1.3m/s), in order to assess the likely dynamic frictional strength Tf of fault rock materials collected from active fault zones in the study areas. Synthetic nano-powders obtained by thermal decomposition of carbonates in a furnace will also be tested. The integration of laboratory friction test results and microstructural studies from both experimental and natural faults should allow the identification of the dominant weakening mechanisms and constrain their operational conditions in natural environments. The permeability of granular materials is controlled by grain size distribution, grain shape, solid volume fraction and pore connectivity. All of these geometric parameters vary across a fault zone. Permeability laboratory measurements will be performed on field samples collected along transects oriented orthogonal and parallel to principal slip surfaces in the fault zones. These data can provide useful 'snapshot' information on the evolution of permeability of slip zones under known/controlled conditions (friction, displacement, timing of fluid emissions), which can be used to calibrate/test fluid flow modelling results. We will use a state-of-the-art numerical model (name) to determine the permeability tensor for the range of geometric parameters obtained from quantitative microstructaral analyses. This numerical approach will allow us to explore systematic permeability variations in a way that cannot be achieved through laboratory experiments alone. The rate of dissipation of the fluids generated by thermal decomposition of the carbonate during slip will be quantified, allowing the role they play in fault zone lubrication to be determined.

在碳酸盐等热不稳定岩石的滑动过程中，有三种热激活机制被认为是特别相关的：1)在高应力摩擦微接触(微凸体)处的快速加热；2)释放和/或困在滑移区的加热流体的热加压；以及3)由热诱导的化学分解反应(脱碳)产生的纳米颗粒的润滑作用。为了研究碳酸盐断裂带中的这种化学和物理反应是否会使断层变得极其脆弱，并有利于地震破裂的继续传播，我们提出了一个多学科的研究计划，综合了野外和实验室研究获得的力学、矿物学、显微构造、流体流动特性和模拟数据。将在意大利亚平宁的碳酸盐岩中进行实地研究，以重建天然断裂带的几何形状，识别不同的构造域及其相关的断裂岩组合。野外观测和显微构造/矿物学分析的结合将为分析和解释在实验变形样品中观察到的主要变形过程提供重要的地质约束。这些结果将被用于在识别和描述作为地震滑动事件指示的断层岩和微构造的诊断组合的基础上，对碳酸盐岩中的地震断层岩提出新的分类方案。这种分类将有助于识别沿暴露的断层段的化石地震，因此可以用来解释世界其他地区的古地震断层记录，帮助进行风险/灾害评估。将对固体和粒状碳酸盐岩进行高速摩擦实验，剪切速度与大地震(1.3m/S)相似，以评估从研究区活动断裂带采集的断层岩料的可能动摩擦强度Tf。通过碳酸盐在炉中热分解获得的合成纳米粉末也将进行测试。综合实验室摩擦测试结果和来自实验断层和天然断层的微观结构研究，应该能够识别主要的削弱机制，并限制它们在自然环境中的运行条件。颗粒材料的渗透性受颗粒大小分布、颗粒形状、固体体积分数和孔连通性的控制。所有这些几何参数在断裂带上都是不同的。渗透率实验室测量将对沿断裂带中与主滑动面垂直和平行的横断面收集的野外样品进行。这些数据可以提供有关已知/受控条件(摩擦力、排水量、流体释放时间)下滑动带渗透率演变的有用“快照”信息，这些信息可用于校准/测试流体流动模拟结果。我们将使用最先进的数值模型(NAME)来确定从定量微结构分析中获得的几何参数范围的渗透率张量。这种数值方法将使我们能够以一种仅通过实验室实验无法实现的方式来探索系统的渗透率变化。在滑动过程中碳酸盐热分解产生的流体的耗散率将被量化，从而可以确定它们在断裂带润滑中所起的作用。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

The geochemical signature caused by earthquake propagation in carbonate-hosted faults

DOI：
10.1016/j.epsl.2011.09.001
发表时间：
2011-10-15
期刊：
EARTH AND PLANETARY SCIENCE LETTERS
影响因子：
5.3
作者：
De Paola, Nicola;Chiodini, Giovanni;Shimamoto, Toshihiko
通讯作者：
Shimamoto, Toshihiko

Nano-powder coating can make fault surfaces smooth and shiny: implications for fault mechanics?

DOI：
10.1130/focus062013.1
发表时间：
2013-06
期刊：
Neurosurgical Focus
影响因子：
4.1
作者：
N. Paola
通讯作者：
N. Paola

Coseismic fault lubrication by viscous deformation

DOI：
10.1038/s41561-021-00747-8
发表时间：
2021-05
期刊：
Nature Geoscience
影响因子：
18.3
作者：
G. Pozzi;N. De Paola;S. Nielsen;R. Holdsworth;T. Tesei;M. Thieme;S. Demouchy
通讯作者：
G. Pozzi;N. De Paola;S. Nielsen;R. Holdsworth;T. Tesei;M. Thieme;S. Demouchy

The signature and mechanics of earthquake ruptures along shallow creeping faults in poorly lithified sediments

不良岩化沉积物沿浅层爬行断层地震破裂的特征和机制