CAREER: Large-scale laboratory-generated earthquakes to study earthquake scaling and fluid-fault interactions.

职业：大规模实验室生成的地震，用于研究地震尺度和流体-断层相互作用。

基本信息

批准号：
1847139
负责人：
Gregory McLaskey
金额：
$ 61.16万
依托单位：
Cornell University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1847139&HistoricalAwards=false
关键词：
CAREER Large scale laboratory generated

项目摘要

Earthquakes occur at a variety of scales. Large earthquakes threaten our cities while tiny ones can be used to understand and monitor underground processes. Subsurface fluids play an important role in earthquake source processes. They can trigger fast, destructive, earthquakes or promote slow, nearly-silent, fault slip which can generate weak tremors. To better understand the role of fluids in earthquake processes, the PI will carry out fault-rupture experiments in a controlled laboratory environment on meter-scale rock samples. These experiments will be a stepping stone between previous smaller-scale laboratory studies and larger field studies. In the experiments, sensors will track the fluids on the fault planes and monitor acoustic wave propagation by methods analogous to those used in seismology. The goal is to better understand the role of fluids in the generation of tremors and other seismic signals, and to scale these observations to natural events. This work will improve our capability to interpret seismic observations, notably tremors, hence earthquake hazard assessment. It will also support a graduate student and educational outreaches toward undergraduates and the public.This project focuses on the fundamental processes underlying fluid-assisted earthquake triggering and frictional slip, and the scaling of laboratory observations to the field. The team will carry out rock-rupture experiments. They will use a new apparatus that squeezes a 3-m slab of granite and can generate magnitude-2.5 dynamic slip events, where rupture nucleation, propagation and termination occur within the sample. These new large-scale experiments with confined ruptures allow simulating natural earthquakes in the laboratory. Over 60 sensors are installed on the sample, the laboratory equivalent of seismic and geodetic networks. The simultaneous measurements link seismic observations to fault slips and stress changes. Fluid injection experiments will be first carried out on small transparent plastic samples, where fluids can be tracked visually, then on meter-scale rock samples where fluids will be monitored acoustically. Finally, the results will be compared to those of 20-m-scale fluid-injection experiments at Grimsel underground laboratory in the central Swiss Alps. The goal is to improve the interpretation of natural earthquake and tremor seismograms, hence earthquake hazard assessment. This 5-year project will also support a graduate student and the development of a wooden footbridge building competition. It will engage young people in 4-H programs and at community colleges in up-state NY rural counties, traditionally underrepresented in STEM. The goal will be to scale up a 14 ft. wooden bridge competition that started as a Cornell class project to footbridges that meet local needs in the City of Ithaca and other communities.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.

地震发生在多种尺度上。大地震威胁着我们的城市，而小地震可用于理解和监视地下过程。地下流体在地震源过程中起重要作用。它们可以触发快速，破坏性，地震或促进缓慢，几乎有利的断层滑动，从而产生弱震颤。为了更好地理解流体在地震过程中的作用，PI将在仪表尺度岩石样品上在受控的实验室环境中进行断层破裂实验。这些实验将是以前的较小实验室研究和大型现场研究之间的垫脚石。在实验中，传感器将通过与地震学中使用的方法相似的方法来跟踪断层平面上的流体并监测声波传播。目的是更好地了解流体在产生震颤和其他地震信号中的作用，并将这些观察结果扩展到自然事件。这项工作将提高我们解释地震观测的能力，尤其是震颤，因此是地震危险评估。它还将支持研究生和对大学生和公众的教育宣传。该项目重点介绍了由液体辅助地震触发和摩擦滑移的基本过程，以及将实验室观察缩放到该领域。团队将进行岩石破裂实验。他们将使用一种新的设备，该设备挤压了3米的花岗岩平板，并可以产生2.5的动态滑移事件，其中样品内发生破裂成核，传播和终止。这些新的大规模实验具有狭窄的破裂，允许模拟实验室中的自然地震。样品上安装了60多个传感器，该实验室等效于地震和地震网络。同时测量将地震观察结果与断层滑动和压力变化联系起来。流体注入实验将首先在小的透明塑料样品上进行，在该样品中可以直观地跟踪流体，然后在仪表尺度的岩石样品上进行声学量监测流体。最后，将将结果与瑞士中部阿尔卑斯山格里姆塞尔地下实验室的20 m尺度流体注入实验进行比较。目的是改善对自然地震和震颤地震图的解释，从而改善地震危险评估。这个为期5年的项目还将支持研究生和木制人行道建筑竞赛的发展。它将吸引年轻人参加4-H计划，并在纽约州纽约州乡村县的社区大学中吸引年轻人，传统上代表人数不足。目的是扩大14英尺的木桥竞赛，该竞赛最初是一个康奈尔级项目，向满足伊萨卡市和其他社区当地需求的人行道。这项奖项反映了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来通过评估来支持的。