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

人们感觉地震是震动地面的弹性波，但产生这些波的原因是地表以下数公里处的断层滑动。然而，并不是所有的断层都能产生地震，而且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而不产生弹性波的原因也不完全清楚。与最大危险相关的断层位于俯冲板块边界，例如美国太平洋西北部。这些断层产生了最大的地震和相关的海啸，但它们也是最不为人所知的。断层是否具有破坏性滑动是由断裂带内岩石的力学性质决定的。这项提案将资助设备的升级，用于测量俯冲板块边界断层岩石的力学特性。这些测量的结果将用于确定在给定地区存在的岩石如何决定断层如何滑动，无论是在地震中还是在破坏性较小的情况下。因此，由该设备进行的测量将有助于改进人口稠密地区（如太平洋西北地区）的地震危险模型。沿俯冲板块边界的岩石的物理性质被认为会影响地震和地震滑动之间过渡的深度，以及慢滑动、低频地震和震颤等现象。然而，在俯冲带中，哪些岩性和哪些性质控制着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，研究起来更具挑战性。该奖项将升级捐赠给莱斯大学的三轴岩石变形装置，用于研究俯冲板块边界岩石的本构行为。该仪器将用于测量地震发生带（500摄氏度）温度下的本构行为，应变率超过8个数量级。然后，这些本构关系可以用于沿俯冲巨型逆冲断层滑动的模型，以了解地震可能向陆地和向海洋传播多远，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，升级后的设备将用于学生进行论文研究。实验室成员将通过社交媒体账户与公众交流这项研究。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 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.