Upgrade of a Triaxial Rock Deformation Apparatus to Measure the Rheology of Subduction Megathrusts

地震被认为是震动地面的弹性波，但这些波的原因是地表下几公里处的断层沿着滑动。然而，并不是所有的断层都会产生地震，有些断层在地震中发生破坏性滑动，而另一些断层滑动缓慢，不产生弹性波，其原因尚不完全清楚。与最大危害相关的断层位于俯冲板块的边界，如美国的太平洋西北部。这些断层造成了最大的地震和相关的海啸，但它们也是最不被了解的。断层是否发生破坏性滑动，取决于断层带内岩石的力学性质。这项提议将资助升级用于测量俯冲板块边界断层岩石力学特性的设备。这些测量的结果将用于确定给定地区的岩石如何决定断层如何滑动，无论是在地震中还是破坏性较小。因此，这一设备所进行的测量将有助于改进人口稠密地区（如太平洋西北部）的地震灾害模型。人们认为，沿俯冲板块边界沿着岩石的物理性质会影响地震滑动和地震滑动之间的过渡深度，以及缓慢滑动、低频地震和震颤等现象。然而，对于俯冲带中哪些岩性和哪些属性控制这些过程仍然存在相当大的不确定性，部分原因是俯冲带中存在的矿物种类更多，研究更具挑战性。该奖项将升级捐赠给莱斯大学的三轴岩石变形仪器，用于研究俯冲板块边界沿着岩石的本构行为。该装置将用于测量温度范围跨越孕震区（500摄氏度）和应变率超过8个数量级时的本构行为。 然后，这些本构关系可以用于断层滑动沿着俯冲巨型逆冲断层的模型中，以了解向陆地和向海洋的地震可能传播多远，这将分别告知与地面震动和海啸相关的地震危险。该项目将资助早期职业PI开发岩石变形实验室，升级后的仪器将用于学生进行论文研究。该奖项反映了NSF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 are felt as elastic waves that shake the ground, but the cause of these waves is slip along faults kilometers beneath the surface. Not all faults produce earthquakes, however, and the reasons that some faults slip destructively in earthquakes, whereas others slip so slowly that they do not produce elastic waves are not entirely known. The faults associated with the greatest hazards are found at subduction plate boundaries, such as the Pacific Northwest of the United States. These faults create the largest earthquakes and associated tsunamis, but they are also the least understood. Whether a fault slips destructively or not is controlled by the mechanical properties of the rocks within the fault zone. This proposal will fund the upgrade of equipment that will be used to measure the mechanical properties of rocks from subduction plate boundary faults. The results of these measurements will be used to determine how the rocks present in a given region determine how the faults slip, whether in an earthquake or less destructively. The measurements made by this equipment will, therefore, contribute to improved models of seismic hazards for populous regions, such as the Pacific Northwest.The physical properties of rocks along the subduction plate boundary are thought to affect the depths of transitions between aseismic and seismic slip, and phenomena such as slow slip, low-frequency earthquakes, and tremor. However, there is still considerable uncertainty about which lithologies and which properties control these processes in subduction zones, in part because the minerals present in subduction zones are both more varied and more challenging to study. This award will upgrade a triaxial rock deformation apparatus donated to Rice University for the purpose of studying the constitutive behavior of rocks present along the subduction plate boundary. The apparatus will be used to measure the constitutive behavior at temperatures that span the seismogenic zone (500 degrees C) and over 8 orders of magnitude in strain rate. These constitutive relations can then be used in models of fault slip along subduction megathrusts to understand how far landward and seaward earthquakes might propagate, which will inform seismic hazards associated with ground shaking and tsunamis, respectively. The project will fund the development of a rock deformation laboratory by an early career PI and the upgraded apparatus will be used by students to conduct their thesis research. Lab members will communicate to the public about this research through a social media account.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.