Temporal Variations in Rockfall and Rock-Wall Retreat Rates in a Deglaciated Valley Over the Past 11 K.Y
https://doi.org/10.1130/G47092.1 Manuscript received 10 October 2019 Revised manuscript received 7 January 2020 Manuscript accepted 19 February 2020 © 2020 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Published online 27 March 2020 Temporal variations in rockfall and rock-wall retreat rates in a deglaciated valley over the past 11 k.y. Solmaz Mohadjer, Todd A. Ehlers, Matthias Nettesheim, Marco B. Ott, Christoph Glotzbach and Reinhard Drews Department of Geosciences, University of Tübingen, 72074 Tübingen, Germany ABSTRACT uniform lithology (e.g., Guzzetti et al., 2003). This study addresses the temporal variations in rockfall activity in the 5.2 km2 calcareous Many studies compare rock-wall retreat rates for cliffs of the deglaciated Lauterbrunnen Valley, Switzerland. We did this using 19 campaigns localities in different environments (Siewert et al., of repeated terrestrial laser scans (TLS) over 5.2 yr, power-law predicted behavior from 2012; Curry and Morris, 2004; Hinchliffe and extrapolation of the TLS-derived frequency-magnitude relationship, and estimates of long- Ballantyne, 1999). This comparison may identify time-scale (∼11 k.y.) activity based on the volume of preserved postglacial rockfall talus. factors for differing rates, but it provides limited Results from the short-time-scale observations indicate no statistically significant difference information on the long-term behavior of a given between TLS observations averaging over 1.5 versus 5.2 yr. Rock-wall retreat rates in both rock mass in one location. This study comple- cases are 0.03–0.08 mm/yr. In contrast, the power-law predicted rock-wall retreat rates are ments previous work by calculating rock-wall 0.14–0.22 mm/yr, and long-term rates from talus volumes are 0.27–0.38 mm/yr.
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