Abstract

The timing of the Monte Peron Landslide is revised to 2890 cal. BP based on a radiocarbon-dated sediment stratigraphy of Lago di Vedana. This age fosters the importance of hydroclimatic triggers in the light of accelerating global warming with a predicted increase of precipitation enhancing the regional predisposition to large landslides. Moreover, a layer enriched in allochthonous organic and minerogenic detritus dating to the same wet period is interpreted as response to a younger and yet unidentified mass wasting event in the catchment of Lago di Vedana. Rock debris of the Monte Peron Landslide impounded the Cordevole River valley and created a landslide-dammed lake. Around AD 1150, eutrophication of this lacustrine ecosystem started with intensified human occupation – a process that ended 150 years later, when the river was diverted back into its original bed. Most likely, this occurred due to artificial opening of the river dam. In consequence, Lago di Vedana was isolated from an open and minerogenic to an endorheic and carbonaceous lacustrine system. After a monastery was established nearby in AD 1457, a second eutrophication process was initiated due to intensified land use linked with deforestation. Only in the eighteenth and nineteenth centuries, deposition of organic matter decreased coinciding with climatic (Little Ice Age) and cultural changes. Conversational measures are the likely reasons for a trend towards less eutrophic conditions since AD 1950.

Highlights

  • Landslides are dangerous and extremely rapid natural hazards of mountain regions with the potential of causing hundreds of fatalities like after the Vajont Landslide in the Southern Alps in AD 1963 (Barla and Paronuzzi 2013; Rossato et al 2018)

  • We investigate the lacustrine sediment record of Lago di Vedana, a relict lake of a once much larger landslide-dammed paleolake formed after the catastrophic rock avalanche at Monte Peron

  • As intense precipitation events should have been recorded more frequently than just once in > 2000 years, we suggest that a landslide in the Cordevole River valley or its tributaries occurred prior to 600 BC and its erosional destruction caused the exceptional flood layer recorded by the sediments of Lago di Vedana

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Summary

Introduction

Landslides are dangerous and extremely rapid natural hazards of mountain regions with the potential of causing hundreds of fatalities like after the Vajont Landslide in the Southern Alps in AD 1963 (Barla and Paronuzzi 2013; Rossato et al 2018). Mass wasting events drastically modify natural and human landscapes and significantly change their topography (Petley 2012). As settlements and infrastructure develop into narrow alpine valleys, they become exposed to landslide hazards. Understanding mechanisms, magnitudes, and recurrence intervals of past landslides is mandatory to assess future risks. As risk management and risk reduction activities are forward-looking, they need a past perspective for calibration (Strouth and McDougall 2021), an approach we tackle with this study

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