Collaborative Research: Investigating the interplay between creeping and seismogenic fault sections using large-scale laboratory experiments and high-resolution numerical models

合作研究：利用大规模实验室实验和高分辨率数值模型研究蠕动断层和发震断层之间的相互作用

基本信息

批准号：
1763499
负责人：
Gregory McLaskey
金额：
$ 38.9万
依托单位：
Cornell University
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：
2018-04-15 至 2022-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1763499&HistoricalAwards=false
关键词：
Collaborative Research Investigating interplay between

项目摘要

Frictional and material properties vary along tectonic faults and directly affect the nucleation, propagation and arrest of earthquakes. This heterogeneous character of natural faults is what makes earthquakes complex and difficult to predict. Some fault sections are mostly locked but recurrently host earthquakes. Other sections are creeping and generally stable. However, under poorly understood circumstances, earthquakes that nucleated in an unstable section can propagate far into stable fault sections and result in particularly large and destructive events. This project investigates the causes that lead to activation of the creeping fault sections by combining large-scale laboratory earthquake experiments with physics-based numerical simulations. The modeled fault consists of stable and unstable parts which realistically reproduce the mechanics of earthquakes at heterogeneous faults. A better understanding of the interaction between stable and unstable fault sections will help us evaluate the potential for extremely large earthquakes that will likely enhance existing seismic hazard assessment tools. This project is a benefit to society because it will help us to better understand earthquakes and develop tools to assess these hazards, and it will add to STEM education of students while supporting new researchers in earthquake studies.This research is a collaborative effort to investigate the mechanics of earthquake rupture arrest with focus on heterogeneous fault properties. It combines multiscale laboratory experiments and numerical modeling. The experiments provide physical constraints for the numerical models, while the modeling improves understanding, generalizing, and scaling up the experimental results. Large-scale laboratory earthquake experiments are conducted on a biaxial machine that generates repeatable sequences of dynamic rupture events contained within a 3-m long granite sample. The fault surfaces are coated with gouge to generate patches of velocity-weakening and velocity-strengthening materials. To explore scaling effects, additional experiments are conducted on a 0.76 m tabletop biaxial machine using plastic samples as forcing blocks. Smaller-scale double-direct shear experiments will benchmark the frictional constitutive parameters of the gouge materials, an essential step for the interpretation of the larger-scale laboratory earthquake observations and the development of realistic, high-resolution numerical models of dynamic rupture and arrest. The simulations include sequences of slip events that quantitatively reproduce the relevant scales of the experiments including the actual size of the apparatus and the rupture process zone.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.

摩擦和材料特性随构造断层而变化，直接影响了地震的成核，繁殖和停滞。这种自然断层的异质特征使地震变得复杂且难以预测。一些断层部分大部分是锁定的，但经常举行地震。其他部分蔓延，通常稳定。但是，在了解不足的情况下，在不稳定截面中成核的地震可能会传播到稳定的断层部分，并导致特别大而破坏性的事件。该项目通过将大型实验室地震实验与基于物理的数值模拟相结合，研究了导致爬行断层部分激活的原因。建模的断层由稳定且不稳定的部分组成，这些部分实际上在异质断层上实际繁殖了地震机制。更好地了解稳定和不稳定断层部分之间的相互作用将有助于我们评估极大的地震的潜力，这可能会增强现有的地震危害评估工具。该项目对社会有好处，因为它将帮助我们更好地了解地震并开发评估这些危害的工具，并在支持地震研究中的新研究人员的同时增加对学生的教育。这项研究是一项协作努力，旨在调查地震破裂逮捕的机制，重点关注异构性断层特性。它结合了多尺度实验室实验和数值建模。这些实验为数值模型提供了物理约束，同时建模改善了理解，推广和扩展实验结果。大规模实验室地震实验是在双轴机上进行的，该双轴机产生可重复的动态破裂事件序列，其中包含3米长的花岗岩样品中。断层表面涂有凿子，以生成速度渗透和速度加强材料的斑块。为了探索缩放效果，使用塑料样品作为强迫块在0.76 m的桌面双轴机上进行其他实验。较小规模的双向剪切实验将基准基准磨牙材料的摩擦本构参数，这是解释大型实验室地震观测的重要步骤，并开发了现实的，高分辨率的动态破裂和停滞的高分辨率数值模型。模拟包括一系列滑动事件，这些序列可以定量地重现实验的相关尺度，包括设备的实际规模和破裂过程区域。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影响的审查标准通过评估来获得支持的。