Abstract

Monitoring and early warning systems based on process dynamics gain importance to cope with an increasing number of alpine hazards. The imminent Hochvogel rock slope failure (up to ca. 260,000 m3) is paradigmatic of natural carbonate slope failure dynamics and a benchmark site for developing an effective monitoring and early warning system. The analysis of process dynamics shows constant movement rates (12 mm/a) over the last 3 years but also a response of specific cracks to heavy precipitation events resulting in factor 5 higher movement rates during wet periods. Here, we show valuable lessons learnt during the development of a reliable monitoring system under challenging environmental conditions. The insights into pre-failure slope dynamics acquired at the Hochvogel will help to detect precursors of a final failure and to warn early.

Introduction

The increasing number of alpine hazards necessitates improved strategies for alpine communities to cope with them [1]. Monitoring and early warning systems based on process dynamics gain importance due to their lower cost compared to protective structures [2]. At the same time, reliable early warning requires a detailed and continuous monitoring of instable sites and their underlying processes [3; 4].

Landslide early warning systems at slope-scale are implemented and used all over the world (for a review see [5]). Actively monitored sites in Europe are for example Åknes (NO), Torgiovannetto (IT), Mannen (NO) or Preonzo (CH). Recent well-monitored case studies in metamorphic rock include Pizzo Cengalo (CH) [6], Marzellkamm (AT) [4] and Veslemannen (NO) [7]. But still, advances in rock slope early warning are reliant on more well-documented case studies from sites with different lithologies and overall settings.

The imminent Hochvogel rock slope failure (up to ca. 260,000 m3) is paradigmatic of natural carbonate slope failure dynamics and at the same time underlies very challenging high alpine conditions. Thus, it is a benchmark site for testing a multi-method risk assessment and developing an effective monitoring and early warning system. Our near real time monitoring is implemented in the AlpSense project (www.bgu.tum.de/landslides/alpsense) that aims at development and evaluation of a multi-method anticipation approach for climate change related natural hazards. Here we share valuable lessons learnt during the development of our system under challenging environmental conditions and a first analysis of precipitation-controlled movement rates.

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