eCite Digital Repository
Seismicity on the western Greenland Ice Sheet: surface fracture in the vicinity of active moulins
Citation
Carmichael, JD and Joughin, I and Behn, MD and Das, S and King, MA and Stevens, L and Lizarralde, D, Seismicity on the western Greenland Ice Sheet: surface fracture in the vicinity of active moulins, Journal of Geophysical Research: Earth Surface, 120, (6) pp. 1082-1106. ISSN 2169-9003 (2015) [Refereed Article]
 | PDF 30Mb |
Copyright Statement
© 2015. American Geophysical Union
Abstract
We analyzed geophone and GPS measurements collected within the ablation zone of the
western Greenland Ice Sheet during a ~35 day period of the 2011 melt season to study changes in ice
deformation before, during, and after a supraglacial lake drainage event. During rapid lake drainage, ice flow
speeds increased to ~400% of winter values, and icequake activity peaked. At times >7 days after drainage,
this seismicity developed variability over both diurnal and longer periods (~10 days), while coincident ice
speeds fell to ~150% of winter values and showed nightly peaks in spatial variability. Approximately 95% of
all detected seismicity in the lake basin and its immediate vicinity was triggered by fracture propagation
within near-surface ice (<330m deep) that generated Rayleigh waves. Icequakes occurring before and
during drainage frequently were collocated with the down flow (west) end of the primary hydrofracture
through which the lake drained but shifted farther west and outside the lake basin after the drainage. We
interpret these results to reveal vertical hydrofracture opening and local uplift during the drainage, followed
by enhanced seismicity and ice flow on the downstream side of the lake basin. This region collocates with
interferometric synthetic aperture radar-measured speedup in previous years and could reflect the migration
path of themeltwater supplied to the bed by the lake. The diurnal seismic signal can be associated with nightly
reductions in surface melt input that increase effective basal pressure and traction, thereby promoting elevated
strain in the surficial ice.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | Greenland, supraglacial lakes, GPS, seismology |
| Research Division: | Earth Sciences |
| Research Group: | Geophysics |
| Research Field: | Geodesy |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding knowledge |
| Objective Field: | Expanding knowledge in the environmental sciences |
| UTAS Author: | King, MA (Professor Matt King) |
| ID Code: | 101688 |
| Year Published: | 2015 |
| Funding Support: | Australian Research Council (FT110100207) |
| Web of Science® Times Cited: | 28 |
| Deposited By: | Geography and Environmental Studies |
| Deposited On: | 2015-06-30 |
| Last Modified: | 2017-10-24 |
| Downloads: | 218 View Download Statistics |
Repository Staff Only: item control page