A structural, geomorphological and InSAR study of an active rock slope failure development
I. H. C. Henderson, T. R. Lauknes, P. T. Osmundsen, J. Dehls, Y. Larsen, T. F. Redfield, 2011. "A structural, geomorphological and InSAR study of an active rock slope failure development", Slope Tectonics, M. Jaboyedoff
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Few studies of rockslides have addressed the relationships between structures, geomorphological expression and direct evidence for movement. We employ structural geology, geomorphology and interferometric synthetic aperture radar (InSAR) to investigate the evolution of the surface features developed in response to movement of the Gamanjunni rockslide site in Troms County in northern Norway. The slide is located on a west-facing mountainside, and is bounded by two angled back scarps and a 20°–30° basal sliding plane. The volume is estimated at 24 Mm3 and is therefore among the largest potential rockslides in Norway. InSAR provides a new method to measure the movement of potential rockslides, and thus provides a direct link between qualitative movement data and field observations. We document the relationship between variations in ground movement rates and changing back-scarp geomorphology at the Gamanjunni site as well as movement patterns within the incipient rockslide. We demonstrate that variations in InSAR documents millimetre variations in scarp displacement and that this is reflected in the evolving back-scarp geometry. We conclude that InSAR can provide important information to complement field observations. The ability of InSAR to document landslide movement patterns greatly extends our knowledge of back-scarp evolution and active landslide processes.
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Usually geomorphology, structural geology and engineering geology provide descriptions of slope instability in quite distinctive ways. This new research is based on combined approaches to providing an integrated view of the operative slope processes. ‘Slope Tectonics’ is the term adopted here to refer to those deformations that are induced or fully controlled by the slope morphology, and that generate features which can be compared to those created by tectonic activity. Such deformation can be induced by the stress field in a slope which is mainly controlled by gravity, topography and the geological setting created by the geodynamic context.
The content of this book includes slope-deformation characterization using morphology and evolution, mechanical behaviour of the material, modes of failure and collapse, influence of lithology and structural features, and the role played by controlling factors. The contributions cover broad aspects of slope tectonics that attempt to underline a multidisciplinary approach, which should create a better framework for studies of slope instability.