Distributed Acoustic Sensing of Seismic Properties in a Borehole Drilled on a Fast-Flowing Greenlandic Outlet Glacier
Distributed Acoustic Sensing of Seismic Properties in a Borehole Drilled on a Fast-Flowing Greenlandic Outlet Glacier
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DOI：
10.1029/2020gl088148
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发表时间：
2020-07-16
影响因子：
5.2
通讯作者：
Chalari, Athena
中科院分区：
文献类型：
--
作者：
Booth, Adam D.;Christoffersen, Poul;Chalari, Athena
分布式声学传感 (DAS) 是一种新技术，利用激光脉冲在光纤电缆中的传播，以高空间和时间分辨率检测地震能量。我们展示了首次部署冰川钻孔 DAS 的分析结果，该部署用于测量存储冰川（格陵兰冰盖快速流动的出口）的冰内和冰下地震特性。我们在 1,043 m 深的垂直地震剖面中记录压缩波和剪切波，以 10 m 垂直分辨率采样，并检测到冰厚度 84% 处从各向同性冰到各向异性冰的转变，这与全新世-威斯康星州转变一致。我们识别了源自 20 m 厚的固结沉积物底部的冰下反射，并通过衰减测量来解释冰川最下面 100 m 的温带冰。我们的研究结果凸显了 DAS 技术在限制冰川和冰盖地震特性方面的巨大潜力。
Distributed Acoustic Sensing (DAS) is a new technology in which seismic energy is detected, at high spatial and temporal resolution, using the propagation of laser pulses in a fiber-optic cable. We show analyses from the first glaciological borehole DAS deployment to measure the englacial and subglacial seismic properties of Store Glacier, a fast-flowing outlet of the Greenland Ice Sheet. We record compressional and shear waves in 1,043 m-deep vertical seismic profiles, sampled at 10 m vertical resolution, and detect a transition from isotropic to anisotropic ice at 84% of ice thickness, consistent with the Holocene-Wisconsin transition. We identify subglacial reflections originating from the base of a 20 m-thick layer of consolidated sediment and, from attenuation measurements, interpret temperate ice in the lowermost 100 m of the glacier. Our findings highlight the promising potential of DAS technology to constrain the seismic properties of glaciers and ice sheets.