Ice thickness estimates of Lemon Creek Glacier, Alaska, from active-source seismic imaging

• Published in: Journal of Glaciology
• Main Authors: Veitch, Stephen A., Karplus, Marianne, Kaip, Galen, Gonzalez, Lucia F., Amundson, Jason M., Bartholomaus, Timothy C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2021
• Subjects: Earth-Surface Processes; Juneau Icefield; Lemon Creek; glacier; Journal of Glaciology; Alaska
• Online Access: http://dx.doi.org/10.1017/jog.2021.32; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143021000320

Abstract Lemon Creek Glacier, a temperate valley glacier in the Juneau Icefield of Southeast Alaska, is the site of long running (>60 years) glaciological studies. However, the most recent published estimates of its thickness and subglacial topography come from two ~50 years old sources that are not in agreement and do not account for the effects of years of negative mass balance. We collected a 1-km long active-source seismic line on the upper section of the glacier parallel and near to the centerline of the glacier, roughly straddling the equilibrium-line altitude. We used these data to perform joint reflection-refraction velocity modeling and reflection imaging of the glacier bed. We find that this upper section of Lemon Creek Glacier is as much as 150 m (~65%) thicker than previously suggested with a large overdeepening in an area previously believed to have a uniform thickness. Our results lead us to reinterpret the impact of basal motion on ice flow and have a significant impact on expectations of subglacial hydrology. We suggest that further efforts to develop a whole-glacier model of subglacial topography are necessary to support studies that require accurate models of ice thickness and subglacial topography.