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Physical Sciences and Mathematics Commons™
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Full-Text Articles in Physical Sciences and Mathematics
Monitoring Glacier Surface Seismicity In Time And Space Using Rayleigh Waves, T. D. Mikesell, K. Van Wijk, M. M. Haney, J. H, Bradford, H. P. Marshall, Joel T. Harper
Monitoring Glacier Surface Seismicity In Time And Space Using Rayleigh Waves, T. D. Mikesell, K. Van Wijk, M. M. Haney, J. H, Bradford, H. P. Marshall, Joel T. Harper
Geosciences Faculty Publications
Sliding glaciers and brittle ice failure generate seismic body and surface wave energy characteristic to the source mechanism. Here we analyze continuous seismic recordings from an array of nine short-period passive seismometers located on Bench Glacier, Alaska (USA) (61.033N, 145.687W). We focus on the arrival-time and amplitude information of the dominant Rayleigh wave phase. Over a 46-hour period we detect thousands of events using a cross-correlation based event identification method. Travel-time inversion of a subset of events (7% of the total) defines an active crevasse, propagating more than 200 meters in three hours. From the Rayleigh wave amplitudes, we estimate …
Thermal Tracking Of Meltwater Retention In Greenland’S Accumulation Area, Neil F. Humphrey, Joel T. Harper, W. Tad Pfeffer
Thermal Tracking Of Meltwater Retention In Greenland’S Accumulation Area, Neil F. Humphrey, Joel T. Harper, W. Tad Pfeffer
Geosciences Faculty Publications
Poorly understood processes controlling retention of meltwater in snow and firn have important implications for Greenland Ice Sheet’s mass balance and flow dynamics. Here we present results from a 3 year (2007-2009) field campaign studying firn thermal profiles and density structure along an 85 km transect of the percolation zone of west Greenland. We installed one or two thermistor strings at 14 study sites, each string having 32 sensors spaced between 0 and 10 m depth. Data from our network of over 500 sensors were collected at 15-60 min intervals for 1-2 years, thereby recording the thermal signature of meltwater …
Georadar-Derived Estimates Of Firn Density In The Percolation Zone, Western Greenland Ice Sheet, Joel Brown, John Bradford, Joel T. Harper, W. Tad Pfeffer, Neil Humphrey, Ellen Mosley-Thompson
Georadar-Derived Estimates Of Firn Density In The Percolation Zone, Western Greenland Ice Sheet, Joel Brown, John Bradford, Joel T. Harper, W. Tad Pfeffer, Neil Humphrey, Ellen Mosley-Thompson
Geosciences Faculty Publications
Greater understanding of variations in firn densification is needed to distinguish between dynamic and melt-driven elevation changes on the Greenland ice sheet. This is especially true in Greenland’s percolation zone, where firn density profiles are poorly documented because few ice cores are extracted in regions with surface melt.We used geoader to investigate firn density variations with depth along an about 70 km transect through a portion of the accumulation area in western Greenland that partially melts. We estimated electromagnetic wave velocity by inverting reflection travel times picked from common midpoint gathers. We followed a procedure designed to find the simplest …