Collaborative Research: RAPID: Response to the 29 July 2021 Chignik M8.2 Earthquake

这一快速奖是对2021年7月阿拉斯加半岛发生的Chignik地震(M8.2级)的回应。这是美国自1965年以来最大的一次地震。它断裂了阿拉斯加半岛近海的一段巨型断裂，上一次断裂是在1938年。该项目部署了一个综合的陆地观测实地活动：大地测量学快速重新测量附近的古迹并记录与地震有关的形变，地震学部署附近的仪器来记录余震。了解这场地震将为评估地震行为模型提供关键信息，从而评估地球上最大地震的危险性。虽然只发生了一次小海啸，但更好地了解破裂将有助于更现实的海啸风险评估。地震还通过迅速向地震和大地测量研究界提供数据，为扩大对科学的参与提供了大量机会。该项目包括与当地学校、社区和政府进行接触，并重新启动一个关注阿拉斯加地球物理的热门博客。奇格尼克地震是仪器记录中罕见的断层段有两次大地震的例子，也是检验地震周期如何工作的理论的关键地点。这次地震遵循了以前记录的沿走向分段的模式，这些分段在锁定行为和地震历史上存在很大差异。这种分段的原因(或者更广泛地说，滑动行为变化的原因)仍然不确定，收集新的数据可能会阐明地震间和同震破裂分段背后的控制机制。此外，这次地震提供了一个很好的实验室来检验断层段之间的载荷理论和我们对震后变形的理解。几乎就在一年前，一架M7.8级地震打破了西面毗邻舒马金的路段，表明有一定的触发可能性。可以探索这种关系，以及使东方的下一个细分市场更接近失败的可能性。该项目利用了数十年来在舒马金斯、阿拉斯加半岛和附近岛屿进行的大地测量工作，以及2018-2009年由GeoPRISMS-EarthScope支持的阿拉斯加两栖社区地震实验。该项目的成果将对解决与美国国家科学、工程和医学研究院的地球及时报告中阐明的地震特征有关的问题很有价值。这一奖项反映了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。

This RAPID award is a response to The July 2021 Chignik earthquake (M8.2) along the Alaskan Peninsula. This is the biggest earthquake in the US since 1965 (Rat Islands). It ruptured a segment of the megathrust offshore of the Alaska Peninsula, which last ruptured in 1938. The project deploys an integrated on-land observational field campaigns: geodesy to rapidly resurvey nearby monuments and document earthquake-related deformation, and seismology to deploy nearby instruments to record aftershocks. Understanding this earthquake will provide critical information for evaluating models of earthquake behavior and hence hazard among the planet’s largest earthquakes. Although only a small tsunami occurred, understanding better the rupture will allow for more realistic tsunami hazard assessments. The earthquake also provides ample opportunities for broadening participation in science, through rapidly making available data to the seismic and geodetic research communities. The project includes outreach to local schools, communities and governments and restarts a popular blog focused on geophysics in Alaska.The Chignik earthquake is a very rare example of a fault segment with two great earthquakes in the instrumental record, and is a critical locale to test theories of how seismic cycles work. The earthquake follows a pattern of along-strike segmentation previously documented between segments with large differences in locking behaviors and earthquake histories. The cause of this segmentation (or indeed of the variation in slip behavior more generally) remains uncertain, and collecting new data may elucidate the controlling mechanisms behind interseismic and coseismic rupture segmentation. Additionally, the earthquake provides an excellent laboratory to test theories of fault loading between segments and of our understanding of postseismic deformation. Almost precisely a year earlier, a M7.8 ruptured the abutting Shumagin segment to the west, indicating some possibility of triggering. That relationship can be explored, as well as the potential for bringing the next segment to the east closer to failure. The project takes advantage of decades of geodetic work on the Shumagins, Alaska Peninsula, and nearby islands, and the large 2018-9 GeoPRISMS-EarthScope-supported Alaska Amphibious Community Seismic Experiment. The project's outcome will be valuable in addressing questions related to the characteristics of earthquakes as articulated in the Earth in Time report from the National Academies of Science, Engineering and Medicine.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.