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

地震发生的尺度各不相同。大地震威胁着我们的城市，而小地震可以用来了解和监测地下活动。地下流体在震源过程中起着重要的作用。它们可以引发快速的、破坏性的地震，或者促进缓慢的、几乎无声的断层滑动，从而产生微弱的震动。为了更好地了解流体在地震过程中的作用，PI将在受控的实验室环境中对米尺度的岩石样本进行断层破裂实验。这些实验将成为以前小规模实验室研究和大规模实地研究之间的垫脚石。在实验中，传感器将跟踪断层面上的流体，并通过类似地震学中使用的方法监测声波的传播。目标是更好地理解流体在地震和其他地震信号产生中的作用，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，特别是地震，从而进行地震危险性评估。它还将支持一名研究生，并向本科生和公众提供教育服务。该项目侧重于流体辅助地震触发和摩擦滑动的基本过程，以及将实验室观测结果与现场相结合。这个小组将进行岩石破裂实验。他们将使用一种新的设备，挤压一块3米厚的花岗岩板，可以产生2.5级的动态滑动事件，在这种情况下，试样内部会发生破裂成核、扩展和终止。这些新的有约束破裂的大规模实验可以在实验室中模拟自然地震。样品上安装了60多个传感器，相当于实验室的地震和大地测量网。同时测量将地震观测与断层滑动和应力变化联系起来。流体注入实验将首先在小的透明塑料样品上进行，在那里可以直观地跟踪流体，然后在米尺度的岩石样品上进行，在那里流体将被声学监测。最后，将结果与瑞士阿尔卑斯中部格里姆塞尔地下实验室20米尺度的流体注入实验结果进行比较。目标是改进对自然地震和震颤地震记录的解释，从而进行地震危险性评估。这个为期5年的项目还将支持一名研究生和一个木制人行桥建筑竞赛的发展。它将吸引年轻人参加4-H项目和纽约州北部农村县的社区大学，这些县传统上在STEM领域的代表性不足。目标是将一个14英尺的木桥竞赛扩大到人行桥，该竞赛最初是康奈尔大学的一个项目，以满足伊萨卡市和其他社区的当地需求。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.