EAR PF: Investigating the competition between thermal pressurization and dilatancy on rough surfaces at earthquake slip rates

该奖项全部或部分由2021年美国救援计划法案（公法117-2）资助。NSF博士后奖学金已授予Monica Barbery博士，以在布朗大学研究地震物理学，由Terry Tullis博士指导。Barbery博士将致力于了解岩石在断层快速运动时产生的摩擦力下的行为。博士后研究员将使用新的实验机械进行第一次岩石摩擦实验的速度和压力的真实的地震，以了解地震过程和相关的风险。这项工作将提高将现有实验室结果与自然相结合的能力。这项研究将有助于开发和修改新的和现有的地震模型，在减轻地震风险方面发挥重要作用。除了这些研究活动外，Barbery博士还将与普罗维登斯公立学校合作，为布朗大学的教育推广计划开发和实施课程，并将在地球，环境，热孔隙流体加压（TP）的动态弱化和渗透硬化（DH）的动态强化是理论上有助于地震期间断层摩擦强度和稳定性的机制。TP的发生是由于过热的孔隙流体沿着不排水断层膨胀，使断层逐渐弱化。DH的发生是由于剪切过程中微裂纹的发展，以及先前配对的断层面由于滑动而变得不配对，这两种情况都增加了孔隙空间并使断层进一步加强。这两个过程是紧密联系在一起的粗糙度和位移历史的滑动面，但TP只会显着地贡献的摩擦削弱，导致地震不稳定，如果DH是最小的。将使用新改进的旋转剪切仪进行岩石摩擦实验，以检查TP和DH在高滑动速率（≥100 mm/s）、高围压（≥25 MPa）和高孔隙压力（≥25 MPa）下的功效。实验结果将与建模相结合，以表征TP和DH之间的竞争，在一系列的滑动率，粗糙度和位移尺度，以更好地了解如何缩放DH和TP过程的地震上的天然future.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).An NSF EAR Postdoctoral Fellowship has been awarded to Dr. Monica Barbery to investigate earthquake physics at Brown University under the mentorship of Dr. Terry Tullis. Dr. Barbery will work to understand how rocks behave when exposed to the friction produced when there is rapid movement on a fault. The postdoctoral fellow will use new experimental machinery to conduct the first rock friction experiments at the velocity and pressures of real earthquakes to understand earthquake processes and the associated risks. This work will improve the ability to scale existing laboratory results to nature. This research will help in the development and modification of new and existing earthquake models that play a vital role in mitigating earthquake risk. In addition to these research activities, Dr. Barbery will work with Providence public schools to develop and implement curriculum for an educational outreach program at Brown University and will co-teach a stacked graduate and undergraduate course within the Department of Earth, Environmental, and Planetary Sciences.Dynamic weakening by thermal pore fluid pressurization (TP) and dynamic strengthening by dilatancy hardening (DH) are mechanisms theorized to contribute to the frictional strength and stability of faults during earthquakes. TP occurs as frictionally heated pore fluids expand along undrained faults to frictionally weaken the fault. DH occurs as microcracks develop during shearing and as previously mated fault surfaces become unmated with slip, both of which increase pore space and frictionally strengthen the fault. Both processes are closely tied to the roughness and displacement history of the sliding surface however TP will only contribute significantly to the frictional weakening that leads to earthquake instability if DH is minimal. Rock friction experiments will be conducted to examine the efficacy of TP and DH at elevated slip rates (≥100 mm/s), elevated confining pressure (≥25 MPa), and elevated pore pressure (≥25 MPa) using a newly modified rotary shear apparatus. Experiment results will be combined with modelling to characterize the competition between TP and DH across a range of slip rate, roughness, and displacement scales to better understand how to scale DH and TP processes to earthquakes on natural faults.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.