Mid-Holocene cluster of large-scale landslides revealed in the Southwestern Alps by 36Cl dating. Insight on an Alpine-scale landslide activity

Zérathe, Swann; Lebourg, Thomas; Braucher, Régis; Bourlès, Didier

doi:10.1016/j.quascirev.2014.02.015

Cited by 106 publications

(94 citation statements)

References 129 publications

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“…The idea that these sackungen did initiate at the termination of prolonged humid period is in accordance with Crozier's (2010) idea, that deep-seated slope failures are generated by long-term climate cycles. Similar climatic controls on Holocene rock slope failures in the European Alps have been recently reported by Prager et al (2008) and Zerathe et al (2014). Thus, we hypothesize that prolonged elevated water tables, increased pore-water pressures and long-term gradual reductions in rock mass strength created favourable conditions for the progression of DSGSD during the Holocene at both studied ridges, even where glacial pre-conditioning is not present.…”

Section: Double-crested Ridge In the Northern Part Of The Ondřejník Lsupporting

confidence: 84%

Are sackungen diagnostic features of (de)glaciated mountains?

et al. 2015

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Section: Double-crested Ridge In the Northern Part Of The Ondřejník Lsupporting

confidence: 84%

Are sackungen diagnostic features of (de)glaciated mountains?

et al. 2015

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“…Field monitoring, historical documentation and palaeostudies indicate that precipitation variations can be a dominant trigger factor in the timing of RSFs, but both cooler conditions and indirect effects such as variations in cleft water pressure, frost shattering and permafrost degradation have also been implicated in rock-slope instability (Eisbacher & Clague 1984;Matthews et al 1997;Trauth et al 2000Trauth et al , 2003Dapples et al 2003;Soldati et al 2004;Prager et al 2008;Borgatti & Soldati 2010;Crozier 2010;Blikra & Christiansen 2014;Zerathe et al 2014;Johnson et al 2017). -The 'cool/wet-climate-response model' applies particularly to the Holocene, reflecting several possible effects of climatic variations on RSF activity.…”

Section: Previous Models Of the Timing Of Rsfsmentioning

confidence: 99%

Small rock‐slope failures conditioned by Holocene permafrost degradation: a new approach and conceptual model based on Schmidt‐hammer exposure‐age dating, Jotunheimen, southern Norway

Matthews

Winkler

Wilson

et al. 2018

Boreas

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October): Small rock-slope failures conditioned by Holocene permafrost degradation: a new approach and conceptual model based on Schmidt-hammer exposure-age dating, Jotunheimen, southern Norway.Rock-slope failures (RSFs) constitute significant natural hazards, but the geophysical processes that control their timing are poorly understood. However, robust chronologies can provide valuable information on the environmental controls on RSFoccurrence: information that can inform models of RSF activity in response to climatic forcing. This study uses Schmidt-hammer exposure-age dating (SHD) of boulder deposits to construct a detailed regional Holocene chronology of the frequency and magnitude of small rock-slope failures (SRSFs) in Jotunheimen, Norway. By focusing on the depositional fans of SRSFs (≤10 3 m 3 ), rather than on the corresponding features of massive RSFs (~10 8 m 3 ), 92 singleevent RSFs are targeted for chronology building. A weighted SHD age-frequency distribution and probability density function analysis indicated four centennial-to millennial-scale periods of enhanced SRSF frequency, with a dominant mode at~4.5 ka. Using change detection and discreet Meyer wavelet analysis, in combination with existing permafrost depth models, we propose that enhanced SRSFactivity was primarily controlled by permafrost degradation. Long-term relative change in permafrost depth provides a compelling explanation for the high-magnitude departures from the SRSF background rate and accounts for: (i) the timing of peak SRSF frequency; (ii) the significant lag (~2.2 ka) between the Holocene Thermal Maximum and the SRSF frequency peak; and (iii) the marked decline in frequency in the late-Holocene. This interpretationis supported bygeomorphological evidence, as the spatialdistributionofSRSFs isstrongly correlatedwith the aspect-dependent lower altitudinal limit ofmountain permafrost in clifffaces. Resultsare indicative of a causal relationship between episodes of relatively warm climate, permafrost degradation and the transition to a seasonal-freezing climatic regime. This study highlights permafrost degradation as a conditioning factor for cliff collapse, and hence the importance of paraperiglacial processes; a result with implications for slope instability in glacial and periglacial environments under global warming scenarios.

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“…Huggel et al, 2012;Zerathe et al, 2014;Micheletti et al, 2015;Palazón and Navas, 2016;Wood et al, 2016). The premise behind this work is that to explain impacts of changes in climate on Alpine catchment suspended sediment yield, it is necessary to consider both transport capacity and sediment supply.…”

Section: Introductionmentioning

confidence: 99%

Temperature signal in suspended sediment export from an Alpine catchment

Costa

Molnár

Stütenbecker³

et al. 2018

Hydrol. Earth Syst. Sci.

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Abstract. Suspended sediment export from large Alpine catchments ( > 1000 km 2 ) over decadal timescales is sensitive to a number of factors, including long-term variations in climate, the activation-deactivation of different sediment sources (proglacial areas, hillslopes, etc.), transport through the fluvial system, and potential anthropogenic impacts on the sediment flux (e.g. through impoundments and flow regulation). Here, we report on a marked increase in suspended sediment concentrations observed near the outlet of the upper Rhône River Basin in the mid-1980s. This increase coincides with a statistically significant step-like increase in basin-wide mean air temperature. We explore the possible explanations of the suspended sediment rise in terms of changes in water discharge (transport capacity), and the activation of different potential sources of fine sediment (sediment supply) in the catchment by hydroclimatic forcing. Time series of precipitation and temperature-driven snowmelt, snow cover, and ice melt simulated with a spatially distributed degreeday model, together with erosive rainfall on snow-free surfaces, are tested to explore possible reasons for the rise in suspended sediment concentration. We show that the abrupt change in air temperature reduced snow cover and the contribution of snowmelt, and enhanced ice melt. The results of statistical tests show that the onset of increased ice melt was likely to play a dominant role in the suspended sediment concentration rise in the mid-1980s. Temperature-driven enhanced melting of glaciers, which cover about 10 % of the catchment surface, can increase suspended sediment yields through an increased contribution of sediment-rich glacial meltwater, increased sediment availability due to glacier recession, and increased runoff from sediment-rich proglacial areas. The reduced extent and duration of snow cover in the catchment are also potential contributors to the rise in suspended sediment concentration through hillslope erosion by rainfall on snow-free surfaces, and increased meltwater production on snow-free glacier surfaces. Despite the rise in air temperature, changes in mean discharge in the mid-1980s were not statistically significant, and their interpretation is complicated by hydropower reservoir management and the flushing operations at intakes. Overall, the results show that to explain changes in suspended sediment transport from large Alpine catchments it is necessary to include an understanding of the multitude of sediment sources involved together with the hydroclimatic conditioning of their activation (e.g. changes in precipitation, runoff, air temperature). In addition, this study points out that climate signals in suspended sediment dynamics may be visible even in highly regulated and human-impacted systems. This is particularly relevant for quantifying climate change and hydropower impacts on streamflow and sediment budgets in Alpine catchments.

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Mid-Holocene cluster of large-scale landslides revealed in the Southwestern Alps by 36Cl dating. Insight on an Alpine-scale landslide activity

Cited by 106 publications

References 129 publications

Are sackungen diagnostic features of (de)glaciated mountains?

Are sackungen diagnostic features of (de)glaciated mountains?

Small rock‐slope failures conditioned by Holocene permafrost degradation: a new approach and conceptual model based on Schmidt‐hammer exposure‐age dating, Jotunheimen, southern Norway

Temperature signal in suspended sediment export from an Alpine catchment

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