Papers by Thierry Oppikofer
Contamination des eaux souterraines par des composés organiques volatils dans la décharge industrielle de Bonfol: apports de la géochimie isotopique
Retrogressive landslide monitoring by TLS: precursory displacements and final collapse. Case study at Val Canaria (Ticino, Switzerland)
… 2010, held 2-7 May …, Jan 1, 2010
In this paper we show the application of ground based LIDAR technique for the monitoring and char... more In this paper we show the application of ground based LIDAR technique for the monitoring and characterization of a landslide that occurred the 27 of October of 2009 in Val Canaria (Ticino, Southern Swiss Alps). The study area corresponds to a retrogressive landslide ...
Journal of Geophysical …, Jan 1, 2011
1] The basal sliding surfaces in large rockslides are often composed of several surfaces and poss... more 1] The basal sliding surfaces in large rockslides are often composed of several surfaces and possess a complex geometry. The exact morphology and location in three dimensions of the sliding surface remains generally unknown, in spite of extensive field and subsurface investigations, such as those at the Åknes rockslide (western Norway). This knowledge is crucial for volume estimations, failure mechanisms, and numerical slope stability modeling. This paper focuses on the geomorphologic characterization of the basal sliding surface of a postglacial rockslide scar in the vicinity of Åknes. This scar displays a stepped basal sliding surface formed by dip slopes of the gneiss foliation linked together by steeply dipping fractures. A detailed characterization of the rockslide scar by means of high-resolution digital elevation models permits statistical parameters of dip angle, spacing, persistence, and roughness of foliation surfaces and step fractures to be obtained. The characteristics are used for stochastic simulations of stepped basal sliding surfaces at the Åknes rockslide. These findings are compared with previous models based on geophysical investigations. This study discusses the investigation of rockslide scars and rock outcrops for a better understanding of potential rockslides. This work identifies possible basal sliding surface locations, which is a valuable input for volume estimates, design and location of monitoring instrumentation, and numerical slope stability modeling. Citation: Oppikofer, T., M. Jaboyedoff, A. Pedrazzini, M.-H. Derron, and L. H. Blikra (2011), Detailed DEM analysis of a rockslide scar to characterize the basal sliding surface of active rockslides,
geoserver.ing.puc.cl
We present the application of terrestrial laser scanning (TLS) for the monitoring and characteriz... more We present the application of terrestrial laser scanning (TLS) for the monitoring and characterization of an active landslide area in Val Canaria (Ticino, Southern Swiss Alps). At catchment scale, the study area is affected by a large Deep Seated Gravitational Slope Deformation (DSGSD) area presenting, in the lower boundary, several retrogressive landslides active since the 1990s. Due to its frequent landslide events this area was periodically monitored by TLS since 2006. Periodic acquisitions provided new information on 3D displacements at the bottom of slope and the detection of centimetre to decimetre level scale changes (e.g. rockfall and pre-failure deformations). In October 2009, a major slope collapse occured at the bottom of the most unstable area. Based on the comparison between TLS data before and after the collapse, we carried out a detailed failure mechanism analysis and volume calculation.
Slope Tectonics, Jan 1, 2011
CITATIONS 22 READS 94 6 authors, including: Some of the authors of this publication are also work... more CITATIONS 22 READS 94 6 authors, including: Some of the authors of this publication are also working on these related projects: CHANGES View project A free and open-source webGIS based learning environment for environmental risk (RISKGIS) View project
ROCK-FALL INVESTIGATION AND HAZARD ASSESSMENT IN YOSEMITE VALLEY, CALIFORNIA, USING AIRBORNE AND TERRESTRIAL LASER SCANNING …
2010 GSA Denver …, Jan 1, 2010
Rock falls are common from the glacially steepened walls of Yosemite Valley, shaping the valley&#... more Rock falls are common from the glacially steepened walls of Yosemite Valley, shaping the valley's iconic rock formations but also posing potentially serious hazards. Laser scanning data allows for new analyses to investigate rock falls and assess hazards with increased ...
Detection, analysis and monitoring of slope movements by high-resolution digital elevation models
Geological Society, …, Jan 1, 2011
CITATIONS 22 READS 94 6 authors, including: Some of the authors of this publication are also work... more CITATIONS 22 READS 94 6 authors, including: Some of the authors of this publication are also working on these related projects: CHANGES View project A free and open-source webGIS based learning environment for environmental risk (RISKGIS) View project
Canadian …, Jan 1, 2009
For more than 10 years, digital elevation models (DEM) produced by light detection and ranging (L... more For more than 10 years, digital elevation models (DEM) produced by light detection and ranging (LIDAR) technology have provided new tools for geomorphologic studies and especially for landslide studies. In particular, terrestrial laser scanning (TLS) provides a great versatility of use. TLS can be used either for monitoring purposes or in an emergency situation that necessitates a rapid DEM acquisition for assessing a hazard. Using three examples we demonstrate the usefulness of TLS for landslide volume quantification, profile creation, and time series analysis. These case studies are landslides located in sensitive clays of eastern Canada (Quebec, Canada) or small rotational slides in river banks (Switzerland).
Natural Hazards, Jan 1, 2010
This paper presents a short history of the appraisal of laser scanner technologies in geosciences... more This paper presents a short history of the appraisal of laser scanner technologies in geosciences used for imaging relief by high-resolution digital elevation models (HRDEMs) or 3D models. A general overview of light detection and ranging (LIDAR) techniques applied to landslides is given, followed by a review of different applications of LIDAR for landslide, rockfall and debris-flow. These applications are classified as: (1) Detection and characterization of mass movements; (2) Hazard assessment and susceptibility mapping; (3) Modelling; (4) Monitoring. This review emphasizes how LIDARderived HRDEMs can be used to investigate any type of landslides. It is clear that such HRDEMs are not yet a common tool for landslides investigations, but this technique has opened new domains of applications that still have to be developed.
Natural Hazards …, Jan 1, 2009
Terrestrial laser scanning (TLS) provides highresolution point clouds of the topography and new T... more Terrestrial laser scanning (TLS) provides highresolution point clouds of the topography and new TLS instruments with ranges exceeding 300 m or even 1000 m are powerful tools for characterizing and monitoring slope movements. This study focuses on the 35 million m 3Å knes rockslide in Western Norway, which is one of the most investigated and monitored rockslides in the world. The TLS point clouds are used for the structural analysis of the steep, inaccessible main scarp of the rockslide, including an assessment of the discontinuity sets and fold axes. TLS acquisitions in 2006, 2007 and 2008 provide information on 3-D displacements for the entire scanned area and are not restricted like conventional survey instruments to single measurement points. The affine transformation matrix between two TLS acquisitions precisely describes the rockslide displacements and enables their separation into translational components, such as the displacement velocity and direction, and rotational components, like toppling. This study shows the ability of TLS to obtain reliable 3-D displacement information over a large, unstable area. Finally, a possible instability model for the upper part ofÅknes rockslide explains the measured translational and rotational displacements by a combination of southward planar sliding along the gneiss foliation, gravitational vertical settlement along the complex, stepped basal sliding surface and northward toppling toward the opened graben structure.
Nature Geoscience, Jan 1, 2008
Uploads
Papers by Thierry Oppikofer