Geologic History and Deformation Monitoring of the Sunnydale Landslide
Date
2024-01-26
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Abstract
The Sunnydale Landslide is a slow-moving rock-slope deformation on the western bank of the Yukon River directly across from Dawson City, Yukon. Field mapping documented road subsidence, expanding tension cracks, recent and ongoing rockfall and shallow landslide activity, and production of detailed geomorphological and surficial geology maps of the landslide. Results from geologic dating of the slide show that is has been a feature of the landscape since at least 10,000 years before present. Due to this age, present rates of surface displacement across the slide are incompatible with observed total deformation, implying either episodic movement or recent acceleration. Results from photograph interpretation and dendrogeomorphological study show deformation throughout much of the 20th century. Additionally, lidar and GNSS/GPS monitoring from 2014 to 2023 show over 20 cm of 3D displacement annually in parts of the landslide. Recent lidar differencing and GNSS data suggests possible acceleration of the landslide, which indicates a higher level of risk of rapid failure and subsequent impacts to Dawson City. Limitations in data availability as well as errors inherent to these data sources preclude certainty on observations of acceleration and probability of rapid failure. The installation of a near real-time GNSS monitoring array in April of 2023 facilitates continued monitoring and clarification of potential changes in rates of motion on the Sunnydale Slide at the time of writing and into the future.
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Geohazards, Geomorphology, Landslide
Citation
Bodtker, J. W. (2024). Geologic history and deformation monitoring of the Sunnydale Landslide (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.