Glacier microseismicity

We present a framework for interpreting small glacier seismic events based on data collected near the center of Bering Glacier, Alaska, in spring 2007. We find extremely high microseismicity rates (as many as tens of events per minute) occurring largely within a few kilometers of the receivers. A hi...

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Bibliographic Details
Published in:Geology (Boulder) 2010-04, Vol.38 (4), p.319-322
Main Authors: West, Michael E, Larsen, Christopher F, Truffer, Martin, O'Neel, Shad, LeBlanc, Laura
Format: Article
Language:English
Subjects:
Alaska
Augustine
Bering Glacier
detection
Earthquakes
Glaciers
microearthquakes
seismicity
Seismology
Southern Alaska
United States
Volcanoes
waveforms
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Summary:We present a framework for interpreting small glacier seismic events based on data collected near the center of Bering Glacier, Alaska, in spring 2007. We find extremely high microseismicity rates (as many as tens of events per minute) occurring largely within a few kilometers of the receivers. A high-frequency class of seismicity is distinguished by dominant frequencies of 20-35 Hz and impulsive arrivals. A low-frequency class has dominant frequencies of 6-15 Hz, emergent onsets, and longer, more monotonic codas. A bimodal distribution of 160,000 seismic events over two months demonstrates that the classes represent two distinct populations. This is further supported by the presence of hybrid waveforms that contain elements of both event types. The high-low-hybrid paradigm is well established in volcano seismology and is demonstrated by a comparison to earthquakes from Augustine Volcano. We build on these parallels to suggest that fluid-induced resonance is likely responsible for the low-frequency glacier events and that the hybrid glacier events may be caused by the rush of water into newly opening pathways.
ISSN:0091-7613
1943-2682
DOI:10.1130/G30606.1