Radar imaging of glaciovolcanic stratigraphy, Mount Wrangell Caldera, Alaska: Interpretation model and results

Glaciological measurements and an airborne radar sounding survey of the glacier lying in Mount Wrangell caldera raise many questions concerning the glacier thermal regime and volcanic history of Mount Wrangell. An interpretation model has been developed that allows the depth variation of temperature, heat flux, pressure, density, ice velocity, depositional age, and thermal and dielectric properties to be calculated. Some predictions of the interpretation model are that the basal ice melting rate is 0.64m yr −1 and the volcanic heat flux is 7.0 W m −2 . By using the interpretation model to calculate two‐way travel time and propagation losses, radar sounding traces can be transformed to give estimates of the variation of power reflection coefficient as a function of depth and depositional age. Prominent internal reflecting zones are located at depths of approximately 59–91 m, 150 m, 203 m, and 230 m. We attribute these internal reflectors to buried horizons of acidic ice, possibly intermixed with volcanic ash, that were deposited during past eruptions of Mount Wrangell. The depositional dates corresponding to these reflecting zones are 1950–1924, 1853, 1770, and 1728 A.D., and we use this information to propose a volcanic history for Mount Wrangell.