Spatial and temporal variations in Greenland glacial‐earthquake activity, 1993–2010
Spatial and temporal variations in Greenland glacial‐earthquake activity, 1993–2010
复制标题
格陵兰冰川地震活动的时空变化，1993-2010
DOI：
10.1029/2012jf002412
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发表时间：
2012
影响因子：
--
通讯作者：
M. Nettles
中科院分区：
文献类型：
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作者：
S. Veitch;M. Nettles
冰川地震是与发生在海洋末端冰川（主要在格陵兰岛）的大冰损事件有关的异常地震。它们在远震上是可探测到的，对源机制的正确理解可以提供一种遥感工具，以补充对这些大型出口冰川的冰川学观测。我们模拟了2006-2010年期间格陵兰岛发生的121次冰川地震的远震表面波波形，以获得其位置和质心-单力源参数。我们将这些结果与前人的成果结合起来，分析了1993-2010年18年间冰川地震发生的时空趋势。我们还研究了六个单独冰川的地震发生情况，将地震记录与独立获得的冰川变化观测结果进行了比较。我们的发现证实了这样的推论，即冰川-地震的地震发生是通过新崩解的大型冰山的倾覆发生的。我们发现冰川退缩、变薄和加速的事件与冰川地震的时间有密切的对应关系，并记录了格陵兰岛西海岸冰川地震在18年的观测期内向北的进展。我们的研究结果还表明，当源冰川的末端非常接近冰川接地线时，即冰川接地或接近接地时，冰川地震就会发生。
[1] Glacial earthquakes are anomalous earthquakes associated with large ice-loss events occurring at marine-terminating glaciers, primarily in Greenland. They are detectable teleseismically, and a proper understanding of the source mechanism may provide a remote-sensing tool to complement glaciological observations of these large outlet glaciers. We model teleseismic surface-wave waveforms to obtain locations and centroid–single-force source parameters for 121 glacial earthquakes occurring in Greenland during the period 2006–2010. We combine these results with those obtained by previous workers to analyze spatial and temporal trends in glacial-earthquake occurrence over the 18-year period from 1993–2010. We also examine earthquake occurrence at six individual glaciers, comparing the earthquake record to independently obtained observations of glacier change. Our findings confirm the inference that glacial-earthquake seismogenesis occurs through the capsize of large, newly calved icebergs. We find a close correspondence between episodes of glacier retreat, thinning, and acceleration and the timing of glacial earthquakes, and document the northward progression of glacial earthquakes on Greenland's west coast over the 18-year observing period. Our results also show that glacial earthquakes occur when the termini of the source glaciers are very close to the glacier grounding line, i.e., when the glaciers are grounded or nearly grounded.