TECTONIC PROCESSES IN SVALBARD TIDE-WATER GLACIER SURGES - EVIDENCE FROM STRUCTURAL GLACIOLOGY

The tectonic effects of a glacier surge differ from those of steady st ate because flow is driven by longitudinal stresses rather than shear stresses. The orientations of recently formed crevasses, indicating th e directions of the principal stresses, have been used to investigate tectonic processes in glacier surges recorded by repeat aerial photogr aphy. Long-term, large-magnitude shifts in stress regime are demonstra ted, as are short-term propagation features. Two types of tide-water g lacier advance are identified, depending on the position of the surge front relative to a low effective-pressure zone at the glacier terminu s.