The Gradenbach Observatory—monitoring deep-seated gravitational slope deformation by geodetic, hydrological, and seismological methods

Abstract

The Gradenbach mass movement (GMM) is an example of DGSD (deep-seated gravitational slope deformation) in crystalline rocks of the Eastern Alps (12.85°E, 47.00°N). The main body of the GMM covers an area of 1.7km 2 and its volume is about 120×10 6 m 3. A reconstruction of the deformation history yields a mean displacement of∼22m from 1962 to . In 1965 /66, 1975 , 2001 , and 2009 high sliding velocities, exceeding several meters per year, interrupt the quasi-stationary periods of slow movement (≤0.3m/year). Since 1999 the displacement of the main body of the GMM has been observed by GPS. Time series of extensometer readings, precipitation, snow cover water equivalent, water discharge, and hydrostatic water level observed in boreholes were re-processed and are presented in this paper. Continuous recording of seismic activity by a seismic monitoring network at the GMM began in the summer of 2006. Deformation has been monitored since 2007 by an embedded strain rosette based on fiber optics technology and a local conventional geodetic deformation network. The velocity of the GMM could be modeled to a large extent by a quantitative relation to hydro-meteorological data. During the phase of high sliding velocity in spring 2009, the seismic activity in the area increased significantly. Several types of seismic events were identified with some of them preceding the acceleration of the main body by about 6 weeks. The potential inherent in the Gradenbach Observatory data to supply early warning and hazard estimation is discussed.

Functioning and precipitation-displacement modelling of rainfall-induced deep-seated landslides subject to creep deformation

“…Few studies focused on landslide creep deformation since such approaches require to perform long-term analyses and thus require multi-annual records of time-series (Corominas et al 2005;Guglielmi et al 2005;Zangerl et al 2010;Klimeš et al 2011;Brückl et al 2013;Crosta et al 2015). There is indeed a need to improve the understanding of landslide creep deformation for which only sparse data limited to rainfall and displacement are generally available.…”

Evaluation of the Use of Sub-Pixel Offset Tracking Techniques to Monitor Landslides in Densely Vegetated Steeply Sloped Areas

“…The theoretical limit will drop with the coherence leading to further underestimation, which is the case in our study. Many slow-moving landslides (~1.6 m/year as defined in [25,26] and cases reported in [27,28]) can exceed this threshold of displacement gradient, especially near the landslide boundary. The sub-pixel Offset Tracking (sPOT) technique (sometimes referred to as Pixel Offset Mapping) has previously been applied to monitor glacier movements, volcanic activities and co-seismic tears in the solid earth resulting from severe earthquakes to address the technical defects and limitations of conventional DInSAR techniques, particularly their sparse coverage and the impact of dense vegetative cover [29].…”

Characterizing the complexity of microseismic signals at slow-moving clay-rich debris slides: the Super-Sauze (southeastern France) and Pechgraben (Upper Austria) case studies

“…In Europe, clayey landslides investigated include the Heumoes slope in the Austrian Vorarlberg Alps (Walter and Joswig, 2008;Walter et al, 2011), the Super-Sauze landslide in the southwest of the French Alps (Walter and Joswig, 2009;Walter et al, 2012;Tonnellier et al, 2013;Provost et al, 2017) and the Valoria landslide in the northern Apennines in Italy (Tonnellier et al, 2013). Examples of case studies carried out at rockslides include, but are not limited to, the following: the Randa rockslide in the Swiss Alps (Eberhardt et al, 2004;Spillmann et al, 2007); the Åknes rockslide in Norway (Roth et al, 2005;Fischer et al, 2014); the Séchili-enne rockslide in the southeastern French Alps (Helmstetter and Garambois, 2010;Lacroix and Helmstetter, 2011); and the Gradenbach, Hochmais-Atemskopf and NiedergallmiggMatekopf deep-seated rock slope deformations in the eastern Austrian Alps Mertl and Brückl, 2007;Brückl et al, 2013).…”