Combining Time-Lapse Photography and Multisensor Monitoring to Understand Frost Creep Dynamics in the Japanese Alps

Automated monitoring that combines time-lapse photography and sensor-based data logging can elucidate the environmental conditions, processes and rates of soil movement on remote periglacial hillslopes. This study presents the results from 5 years of time-lapse photography of soil movements, supported by time series data on frost heave, soil temperature, soil moisture and surface weather, on an alpine stone-banked lobe subject to frequent diurnal freeze-thaw cycles and deep seasonal frost on Mt Ainodake in the Japanese Alps. The lobe is dominated by biannual shallow soil movements, mostly originating from diurnal frost heave by needle ice or shallow ice lens formation and approximated by potential frost creep. The surface velocity shows a small interannual variation mainly reflecting snow conditions that control the spatio-temporal variability of freeze-thaw action, while it is independent of mean annual air temperature that influences the intensity of seasonal freezing. Occasional rill erosion occurs when the topmost frozen soil is rapidly thawed and super-saturated by intensive rainfall during seasonal thawing periods. Copyright © 2014 John Wiley & Sons, Ltd.