Université de Fribourg

Direct observations of a three million cubic meter rock-slope collapse with almost immediate initiation of ensuing debris flows

Walter, Fabian ; Amann, Florian ; Kos, Andrew ; Kenner, Robert ; Phillips, Marcia ; Preux, Antoine de ; Huss, Matthias ; Tognacca, Christian ; Clinton, John ; Diehl, Tobias ; Bonanomi, Yves

In: Geomorphology, 2020, vol. 351, p. 106933

Catastrophic collapse of large rock slopes ranks as one of the most hazardous natural phenomena in mountain landscapes. The cascade of events, from rock- slope failure, to rock avalanche and the near-immediate release of debris flows has not previously been described from direct observations. We report on the 2017, 3.0 × 106 m3 failure on Pizzo Cengalo in Switzerland, which led to human...

Université de Fribourg

Distinguishing ice-rich and ice-poor permafrost to map ground temperatures and ground ice occurrence in the Swiss Alps

Kenner, Robert ; Noetzli, Jeannette ; Hoelzle, Martin ; Raetzo, Hugo ; Phillips, Marcia

In: The Cryosphere, 2019, vol. 13, no. 7, p. 1925–1941

Mountain permafrost is invisible, and mapping it is still a challenge. Available permafrost distribution maps often overestimate the permafrost extent and include large permafrost-free areas in their permafrost zonation. In addition, the representation of the lower belt of permafrost consisting of ice-rich features such as rock glaciers or ice-rich talus slopes can be challenging. These...

Université de Fribourg

New insights on permafrost genesis and conservation in talus slopes based on observations at Flüelapass, Eastern Switzerland

Kenner, Robert ; Phillips, Marcia ; Hauck, Christian ; Hilbich, Christin ; Mulsow, Christian ; Bühler, Yves ; Stoffel, Andreas ; Buchroithner, Manfred

In: Geomorphology, 2017, vol. 290, p. 101–113

The talus slope at Flüelapass was the first mountain permafrost study site in Switzerland in the 1970s and the presence of ice-rich permafrost at the foot of the slope has been investigated in the context of several studies focusing on the role of snow cover distribution. We review previously developed hypotheses and present new ones using various data sources, such as temperature...

Université de Fribourg

Distributed snow and rock temperature modelling in steep rock walls using Alpine3D

Haberkorn, Anna ; Wever, Nander ; Hoelzle, Martin ; Phillips, Marcia ; Kenner, Robert ; Bavay, Mathias ; Lehning, and Michael

In: The Cryosphere, 2017, vol. 11, no. 1, p. 585–607

In this study we modelled the influence of the spatially and temporally heterogeneous snow cover on the surface energy balance and thus on rock temperatures in two rugged, steep rock walls on the Gemsstock ridge in the central Swiss Alps. The heterogeneous snow depth distribution in the rock walls was introduced to the distributed, process-based energy balance model Alpine3D with a...

Université de Fribourg

Thermal and mechanical responses resulting from spatial and temporal snow cover variability in permafrost rock slopes, steintaelli, swiss alps

Draebing, Daniel ; Haberkorn, Anna ; Krautblatter, Michael ; Kenner, Robert ; Phillips, Marcia

In: Permafrost and Periglacial Processes, 2017, vol. 28, no. 1, p. 140–157

The aim of this study is to investigate the influence of snow on permafrost and rock stability at the Steintaelli (Swiss Alps). Snow depth distribution was observed using terrestrial laser scanning and time-lapse photography. The influence of snow on the rock thermal regime was investigated using near-surface rock temperature measurements, seismic refraction tomography and one-dimensional...

Université de Fribourg

Seasonally intermittent water flow through deep fractures in an Alpine Rock Ridge: Gemsstock, Central Swiss Alps

Phillips, Marcia ; Haberkorn, , Anna ; Draebing, Daniel ; Krautblatter, Michael ; Rhyner, Hansueli ; Kenner, Robert

In: Cold Regions Science and Technology, 2016, vol. 125, p. 117–127

Geological investigations and seismic refraction tomography reveal a series of 70° steep, parallel and continuous fractures at 2950 m asl within the Gemsstock rock ridge (Central Swiss Alps), at the lower fringe of alpine permafrost. Temperature measurements in a 40 m horizontal borehole through the base of the ridge show that whilst conductive heat transfer dominates within the rock mass,...

Université de Fribourg

Snow as a driving factor of rock surface temperatures in steep rough rock walls

Haberkorn, Anna ; Hoelzle, Martin ; Phillips, Marcia ; Kenner, Robert

In: Cold Regions Science and Technology, 2015, vol. 118, p. 64–75

Observations show that considerable amounts of snow can accumulate in steep, rough rock walls. The heterogeneously distributed snow cover significantly affects the surface energy balance and hence the thermal regime of the rock walls.To assess the small-scale variability of snow depth and rock temperatures in steep north and south facing rock walls, a spatially distributed multi-method approach...