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Full-Text Articles in Physical Sciences and Mathematics
Crevasse Patterns And The Strain-Rate Tensor: A High-Resolution Comparison, Joel T. Harper, Neil Humphrey, W. Tad Pfeffer
Crevasse Patterns And The Strain-Rate Tensor: A High-Resolution Comparison, Joel T. Harper, Neil Humphrey, W. Tad Pfeffer
Geosciences Faculty Publications
Values of the strain-rate tensor represented at a 20 m length scale are found to explain the pattern and orientation of crevasses in a 0.13 km2 reach of Worthington Glacier, Alaska, U.S.A. The flow field of the reach is constructed from surveyed displacements of 110 markers spaced 20-30 m apart. A velocity gradient method is then used to calculate values of the principal strain-rate axes at the nodes of a 20 m x 20 m orthogonal grid. Crevasses in the study reach are of two types, splaying and transverse, and are everywhere normal to the trajectories of greatest (most …
Mapping Subglacial Surfaces Of Temperate Valley Glaciers By Two-Pass Migration Of A Radio-Echo Sounding Survey, Brian C. Welch, W. Tad Pfeffer, Joel T. Harper, Neil F. Humphrey
Mapping Subglacial Surfaces Of Temperate Valley Glaciers By Two-Pass Migration Of A Radio-Echo Sounding Survey, Brian C. Welch, W. Tad Pfeffer, Joel T. Harper, Neil F. Humphrey
Geosciences Faculty Publications
High-resolution maps of the glacier bed are developed through a pseudo-three-dimensional migration of a dense array of radio-echo sounding profiles. Resolution of three-dimensional maps of sub-glacial surfaces is determined by the radio-echo sounding wavelength, data spacing in the field, and migration. Based on synthetic radio-echo sounding profile experiments, the maximum resolution of the final map cannot exceed one half-wavelength. A methodology of field and processing techniques is outlined to develop a maximum-resolution map of the glacier bed. The field and processing techniques valley glacier in south-central Alaska. The field techniques and the processing steps used on the glacier result in …