Collaborative Research: The 2020-2021 Alaska-Aleutian Earthquake Sequence: Cascading Events & Stress Loading of the Shallow Megathrust

估计未来地震的大小和位置在地震学和灾害研究中仍然是一个难以捉摸的目标。该项目研究了2020年7.8级Simeonof地震和2021年8.2级Chignik地震，这些地震破坏了阿拉斯加近海北美板块和太平洋板块之间更深界面的邻近部分。该项目将探索这两次地震之间的关系：地球对2020年Simeonof事件的反应如何影响2021年Chignik地震中失败的断裂带，该板块界面的构造和几何结构在地震发生中的作用，以及这些事件如何适应沿着该板块边界的更长的地震历史。另一个关键问题是，该地区尚未破裂的较浅板块界面部分是否会在地震中破裂，从而有可能引发毁灭性的太平洋海啸。该项目将在奇格尼克地震断裂带周围部署4台GPS/GNSS仪器，以便更好地捕捉地震后的变形情况。这个项目是阿拉斯加大学、费尔班克斯大学和密歇根州立大学的合作项目。该项目将直接研究西蒙诺夫地震和奇格尼克地震引起的地壳运动和应力变化，以及地震后地球的重新调整。它将利用多种地球物理数据源，包括高精度GPS仪器，结合地壳运动和应力变化建模。对不同构造过程的仔细分离，以及通过精确的地震重新定位得到的真实断层几何模型，将产生关于奇格尼克地震期间和之后板块运动的改进模型。结合Simeonof地震和1938年早些时候同一地区的M8.3地震的类似、单独生成的产品，该项目将创建短期和长期应力变化模型，并研究应力变化如何影响未来的破裂模式。虚拟研讨会将把俯冲带科学家聚集在一起，激发人们对该项目产生的数据的兴趣，展示新的发现，并激发新的科学和未来的机会。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。

Estimating the size and location of future earthquakes remains an elusive goal in seismology and hazard research. This project studies the 2020 M7.8 Simeonof and 2021 M8.2 Chignik earthquakes that ruptured adjacent portions of the deeper interface between the North American and Pacific Plates offshore Alaska. The project will probe the relationship between these two earthquakes: how the Earth’s response to the 2020 Simeonof event may have affected the fault area that failed in the 2021 Chignik earthquake, the role of tectonics and geometry of this plate interface in earthquake occurrence, and how these events fit in the longer history of earthquakes along this plate boundary. Another key question is whether the yet unruptured shallower parts of the plate interface in this region may rupture in earthquakes that have the potential to create devastating, Pacific-wide tsunamis. This project will deploy four GPS/GNSS instruments around the Chignik earthquake rupture to better capture deformation following the earthquake. This project is a collaboration between the University of Alaska, Fairbanks and Michigan State University.This project will study crustal motions and stress changes due to the Simeonof and Chignik earthquakes directly and from readjustments of the Earth after the earthquakes. It will make use of multiple geophysical data sources, including high-precision GPS instrumentation, combined with modeling of crustal motions and stress changes. Careful separation of different tectonic processes, and models of realistic fault geometries informed by accurate earthquake relocation will yield improved models for how the plates moved during and after the Chignik earthquake. Coupled with similar, separately generated products for Simeonof earthquake and the earlier 1938 M8.3 earthquake in the same region, the project will create short- and long-term stress change models, and investigate how stress change may influence future rupture patterns. A virtual workshop will bring together subduction zone scientists, generate interest in the data produced through this project, showcase new findings, and inspire novel science and future opportunities.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.