Collaborative Research: Triggering of Antarctic Icequakes, Slip Events, and other Tectonic Phenomena by Distant Earthquakes

合作研究：远地地震引发南极冰震、滑动事件和其他构造现象

• 批准号: 1543399
• 负责人: Zhigang Peng
• 金额: $ 13.64万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2020-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1543399&HistoricalAwards=false
• 关键词: Collaborative; Research; Triggering; Antarctic; Icequakes

The continent of Antarctica has approximately the same surface area as the continental United States, though we know significantly less about its underlying geology and seismic activity. Multinational investments in geophysical infrastructure over the last few decades, especially broadband seismometers operating for several years, are allowing us to observe many interesting natural phenomena, including iceberg calving, ice stream slip, and tectonic earthquakes. To specifically leverage those past investments, we will analyze past and current data to gain a better understanding of Antarctic seismicity. Our recent research revealed that certain large earthquakes occurring elsewhere in the world triggered ice movement near various stations throughout Antarctica. We plan to conduct an exhaustive search of the terabytes of available data, using cutting-edge computational techniques, to uncover additional evidence for ice crevassing, ice stream slip, and earth movement during earthquakes. One specific focus of our research will include investigating whether some of these phenomena may be triggered by external influences, including passing surface waves from distant earthquakes, ocean tides, or seasonal melt. We plan to produce a catalog of the identified activity and share it publicly, so the public and researchers can easily access it. To reach a broader audience, we will present talks to high school classes, including Advanced Placement classes, in the Austin, Texas and Atlanta, Georgia metropolitan areas with emphasis on general aspects of seismic hazard, climate variability, and the geographies of Antarctica. This project will provide research opportunities for undergraduates, training for graduate students, and support for an early-career scientist.In recent years, a new generation of geodetic and seismic instrumentation has been deployed as permanent stations throughout Antarctica (POLENET), in addition to stations deployed for shorter duration (less than 3 years) experiments (e.g. AGAP/TAMSEIS). These efforts are providing critical infrastructure needed to address fundamental questions about both crustal-scale tectonic structures and ice sheets, and their interactions. We plan to conduct a systematic detection of tectonic and icequake activities in Antarctica, focusing primarily on background seismicity, remotely-triggered seismicity, and glacier slip events. Our proposed tasks include: (1) Identification of seismicity throughout the Antarctic continent for both tectonic and ice sources. (2) An exhaustive search for additional triggered events in Antarctica during the last ~15 years of global significant earthquakes. (3) Determination of triggered source mechanisms and whether those triggered events also occur at other times, by analyzing years of data using a matched-filter analysis (where the triggered local event is used to detect similar events). (4) Further analysis of GPS measurements over a ~5.5 year period from Whillans Ice Plain, which suggests that triggering of stick-slip events occurred after the largest earthquakes. An improved knowledge of how the Antarctic ice sheet responds to external perturbations such as dynamic stresses from large distant earthquakes and recent ice unloading could lead to a better understanding of ice failure and related dynamic processes. By leveraging the vast logistical investment to install seismometers in Antarctica over the last decade, our project will build an exhaustive catalog of tectonic earthquakes, icequakes, calving events, and any other detectable near-surface seismic phenomena.

南极洲大陆的表面积与美国大陆大致相同，尽管我们对其潜在的地质和地震活动知之甚少。过去几十年在地球物理基础设施方面的跨国投资，特别是运行了几年的宽带地震仪，使我们能够观察到许多有趣的自然现象，包括冰山崩解、冰流滑动和构造地震。为了更好地利用过去的投资，我们将分析过去和当前的数据，以更好地了解南极的地震活动。我们最近的研究表明，世界其他地方发生的某些大地震在整个南极洲的各个站点附近引发了冰的移动。我们计划使用尖端计算技术对可用的TB级数据进行彻底搜索，以发现地震期间冰川破裂、冰流滑移和地球运动的更多证据。我们研究的一个具体重点将包括调查其中一些现象是否可能是由外部影响引发的，包括来自遥远地震、海潮或季节性融化的传递的表面波。我们计划制作一份已确定活动的目录并公开分享，这样公众和研究人员就可以很容易地访问它。为了接触到更广泛的听众，我们将在德克萨斯州奥斯汀和佐治亚州亚特兰大大都市地区向高中班级进行演讲，包括高级选修课程，重点是地震灾害、气候变异性和南极洲地理的一般方面。该项目将为本科生提供研究机会，为研究生提供培训，并为初出茅庐的科学家提供支持。近年来，新一代大地测量和地震仪器已被部署为整个南极洲的永久性观测站(POLENET)，此外还部署了持续时间较短(少于3年)的观测站(例如AGAP/TAMSEIS)。这些努力正在提供必要的关键基础设施，以解决有关地壳规模的构造结构和冰盖及其相互作用的根本问题。我们计划对南极的构造和冰震活动进行系统的探测，主要集中在背景地震活动、远程触发的地震活动和冰川滑动事件。我们提出的任务包括：(1)确定整个南极大陆的构造和冰源的地震活动。(2)在近15年的全球大地震中，对南极的其他触发事件进行了详尽的寻找。(3)通过使用匹配过滤器分析来分析多年数据(其中触发的本地事件用于检测类似事件)，确定触发源机制以及这些触发事件是否也在其他时间发生。(4)进一步分析了惠兰冰原约5.5年的GPS观测结果，表明粘滑事件的触发发生在最大地震之后。更好地了解南极冰盖如何对外部扰动作出反应，例如远距离大地震的动应力和最近的冰卸载，可能有助于更好地了解冰的破坏和相关的动态过程。通过利用过去十年在南极洲安装地震仪的巨大后勤投资，我们的项目将建立一个详尽的构造地震、冰震、崩解事件和任何其他可检测到的近地表地震现象的目录。