期刊
ANNALS OF GLACIOLOGY
卷 60, 期 79, 页码 1-13出版社
CAMBRIDGE UNIV PRESS
DOI: 10.1017/aog.2018.32
关键词
crevasses; glacier flow; glacier geophysics; glaciological instruments and methods; seismology
资金
- Southern Regents Educational Board
- Louisiana Board of Regents RCS [LEQSF(2014-17)-RD-A-04]
- NSF [1239277]
- Swiss National Science Foundation (GlaHMSeis Project) [PP00P2_157551]
- Directorate For Geosciences
- Division Of Earth Sciences [1239277] Funding Source: National Science Foundation
Seasonal lake Gornersee forms at the confluence of Gornergletscher and Grenzgletscher, Switzerland, and experiences outburst floods annually in midsummer. To study the interplay between lake drainage, glacier movement and crevasse activity, high-frequency seismometers and GPS receivers were deployed in networks near Gornersee during the summer ablation seasons of 2004, 2006 and 2007. We use a Rayleigh wave coherence method to locate 3289, 7939 and 4087 icequakes, respectively, primarily along well-defined surface crevasses. We calculate two-dimensional strains from triads of GPS stations and find mean differential strain rates of similar to 300 x 10(-6) d(-1) with diurnal variations up to 800 x 10(-6) d(-1). Crevasse icequake activity and glacial velocity are highest during early season, then decrease as meltwater channels erode and subglacial water pressure decreases. Glacial response to Gornersee drainage varied year-to-year, with icequake activity promoted at some crevasses and inhibited at others, suggesting syn-drainage icequakes may be indicative of local drainage patterns and small-scale features of the stress field. Diurnal pulses in icequake activity exhibit peak activity at different times of day in different locations, coincident with a southeast-to-northwest trending concentrated shear zone near the Gornergletscher-Grenzgletscher confluence, likely due to differences in the timing of peak strain rate in these regions.
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