EAGER: Expanding Our Understanding of Seismic Sources via Investigations of Icequakes on an Alpine Glacier

由于技术的进步，地震学家/冰川学家正在获得越来越大、越来越高质量的连续和半连续地震波形流数据集。这些数据无疑包含重要但不易识别的信号，需要额外的用户交互才能正确识别。仔细地提取这些数据，特别是识别更多的外来信号，可能会回答关于冰川物理的关键问题（例如，冰川是如何与基岩耦合的；冰震是否与地震相似）。2004年至2007年四个夏季在瑞士戈纳冰川上记录的约25万次“冰震”就是例证。这项工作将提供一个更广泛的理解由破坏和滑动穿过双材料表面的应力松弛模式的范围，这与从小高山冰川到主要板块边界断层的自然系统有关。完整的戈纳冰川数据集的容量为1tb，其中只有10%被探索过。我们建议利用剩余的~90%的数据：(1)根据GPS和经纬仪测量推断，确定冰震行为（时空和波形频率内容）与冰川系统应变之间的相关性和因果关系；(2)寻找类似震颤的信号并研究其来源。这些努力将使我们能够确定数据中的哪些方面是可重复的，以评估冰川/基岩界面上的滑动与构造断层（即地震）推断的滑动的相似程度，以及如何有效地利用地震技术监测冰川。空前的数据量，跨学科的工作方面（地震学和冰川学），以及新的检测方法使这成为一个潜在的变革性的研究项目。

Given technological advances, seismologists/glaciologists are obtaining ever-increasingly larger and higher quality datasets of continuous and semi-continuous seismic waveform streams. These data undoubtedly contain important, but not readily recognized, signals that require additional user-interaction to properly identify. Carefully distilling these data, particularly to identify the more exotic signals, could potentially answer key questions about the physics of glaciers (e.g., how does a glacier couple to the bedrock; are icequakes similar to earthquakes). This is exemplified by observations of ~250,000 "icequakes" recorded during the four summer seasons 2004-2007 on the Gorner Glacier in Switzerland. This work will provide a broader understanding of the range of modes of stress relaxation by failure and slip across sliding bi-material surfaces, which is relevant to natural systems ranging from small alpine glaciers to major plate-boundary faults. The complete Gorner Glacier dataset has a volume of ~1 terabyte of which only ~10% has been explored. We propose to exploit the remaining ~90% of data to: (1) identify correlations and thus causal connections between the behavior of icequakes (temporal/spatial and waveform frequency content) and strain within the glacier system as inferred from GPS and theodolite measurements; and (2) search for tremor-like signals and study their sources. These efforts will allow us to identify what aspects in the data are repeatable season to season, to assess the extent to which slip on glacial/bedrock interfaces is analogous to that inferred on tectonic faults (i.e., earthquakes), and how to efficiently monitor glaciers with seismic techniques. The culmination of this unprecedented amount of data, the interdisciplinary aspect of the work (seismology and glaciology), and the novel detection methods make this a potentially transformative research project.