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

在地震学和灾害研究中，估计未来地震的规模和位置仍然是一个难以实现的目标。该项目研究了2020年西蒙诺夫M7.8级和2021年奇格尼克8.2级地震，这两次地震打破了阿拉斯加近海北美板块和太平洋板块之间较深界面的相邻部分。该项目将探索这两次地震之间的关系：地球对2020年Simeonof地震的反应可能如何影响在2021年Chignik地震中失败的断层区，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该板块边界的更长时间的地震历史。另一个关键问题是，该地区尚未破裂的板块界面较浅部分是否会在地震中破裂，从而有可能在整个太平洋地区引发毁灭性的海啸。该项目将在Chignik地震破裂周围部署四个GPS/GNSS仪器，以更好地捕捉地震后的变形。该项目是阿拉斯加大学费尔班克斯分校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来源，包括高精度全球定位系统仪器，并结合地壳运动和应力变化的建模。仔细分离不同的构造过程，并通过准确的地震定位获得真实断层几何模型，将改进板块在Chignik地震期间和之后如何移动的模型。结合为同一地区的Simeonof地震和1938年早些时候的8.3级地震单独生成的类似产品，该项目将创建短期和长期应力变化模型，并研究应力变化可能如何影响未来的破裂模式。一个虚拟研讨会将把俯冲带科学家聚集在一起，激发人们对通过这个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NSF的法定使命，并通过使用基金会的智力优势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.