UBC Theses and Dissertations
Radar imaging glacio-volcanic stratigraphy : Mt. Wrangell, Alaska Cross, Guy Matthew
An airborne radar survey was conducted over the ice-filled volcanic caldera at Mt. Wrangell, Alaska. Research reported here involves computer processing and interpretation of radio-reflection data acquired over 21 traverses of the summit. In addition to describing useful data enhancement techniques, a dynamic programming approach is introduced for topographically controlled data positioning and spatial correction. Interpretation focusses upon a well defined radio-stratigraphy attributed to high acidity horizons deposited at the ice surface during periods of elevated volcanic activity. A comparative analysis of layer character indicates that echoes from the caldera floor are not continuously detected because of anomalously high signal absorption. Consequently, results impose a lower limit upon maximum ice thickness. A numerical interpretation scheme, incorporating both glaciological measurements and empirical relations governing the behaviour of firn and ice, is developed to aid interpretation of the glacio-volcanic stratigraphy. Preliminary modelling yields a speculative volcanic record that roughly matches the known eruption sequence at Mt. Wrangell and suggests a significant extension of the volcanic history.
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