Recent Interannual Variations of Rock Glacier Creep in the European Alps
Résumé
Recent interannual variations of rock glacier surface motion are compared for 16 landforms monitored for a few years in various parts of the European Alps. Large fluctuations have been observed particularly since 2002. Most investigated rock glaciers have shown a similar behavior whatever their location in the Alpine arc, their size, or their velocity. The observed interannual variations appear to be primarily related to external climatic factors rather than to internal characteristics. They are mostly well correlated with mean annual ground surface temperature shifts with a delay of a few months, reflecting the thermal wave propagation deeper into permafrost. Seasonal factors may also play a significant role: a lower intensity of winter ground freezing and/or a larger winter snow accumulation appear to facilitate a higher rate of rock glacier surface motion.