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Cliffs observatory
**Scientific objectives
Falling rocks are a natural risk of utmost importance in the foothills of the Alps, in particular in the Grésivaudan Valley. This has led to dense constructions, hundreds of meters tall, at the cliff bases. The systematic study of this phenomenon address relevant activity as well as the precise estimation of the impact of rockslides.
This workshop-observatory is motivated by the creation of referential morphological cliff measurements, associated with precise time measurements of each event on the St Eynard pilot site. This will enable us to determine geometric characteristics of future rockslides (including the origin area, the volume, and the morphology.) Similar campaigns are being carried out simultaneously at the Dent de Crolles.
This workshop seeks to develop the technical reconstruction of the relief using stereo-photogrammetry to achieve a digital surface model (MNS) for internal use.
Other ultra-local temperature and meteorology measures are also underway.
**Organization
The observatory’s cliff measurements are available thanks to a large scientific community including geomechanics, geologists, geographers, developers, and risk managers — all involved in work concerning cliff morphology with the support of the Multidisciplinary Observatory for Slope Instabilities, a national organization whose board of directors is housed at ISTerre.
**Implementation
The assessments of this observation service are focused on the cliffs of St. Eynard pilot site, where we combine measures of morphological erosion and seismological detection in order to increase their avantages and balance out their disadvantages. The measured zones include the cliffs themselves, the origin areas, and other nearby areas (in particular minor slopes at cliff bases) that allow us to gauge the extent of rockslides.
**Parteners
The cliff workshop’s main partners can be found at ISTerre and contribute to the workshop’s planning and coordination, seismological expertise, Lidar measurements, and photography. The relief’s plotting methods are done using photogrammetry (e.g. stereo plotting, correlation, multi-view, etc.) and engage other OSUG laboratories in collaborations at the University of Grenoble-Alpes, Chambéry, and Orléans. These parties have come together on a GIS project currently underway. The workshop is grateful to its Alpine Center for Natural Risks (PARN), one the first supporters and a continued partner in this project.