Multiscale fracture analysis along the French chalk coastline for investigating erosion by cliff collapse
A. Genter, A. Duperret, A. Martinez, R. N. Mortimore, J-L. Vila, 2004. "Multiscale fracture analysis along the French chalk coastline for investigating erosion by cliff collapse", Coastal Chalk Cliff Instability, R. N. Mortimore, A. Duperret
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Coastal cliffs of Upper Normandy and Picardy are eroded by cliff collapses of various sizes. This paper presents a multi-scale analysis of the pre-existing fractures embedded within the Cretaceous chalk. About 20 representative sites equally spaced along the 120km long coastal section were analysed and compared to a continuous structural analysis of the coast derived from aerial photographs taken in 1986. Ancient collapses interpreted on the aerial photos were compared to the pre-existing fracture content. Regional faults, pre-1986 collapse location and fracture density are spatially correlated. However, recent collapses observed on the field between 1998 and 2001 did not systematically correlate to the pre-existing fracture occurrence and therefore, there is no clear link between recent collapse and the regional faults.
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Most of the rocky coastlines around the world are subject to active erosion processes. Because of the growing hazard to local communities from coastal cliff retreat, it is necessary to investigate where, when and how cliffs collapse. The results of these studies are vital for the planners and local authorities responsible for safety and access to cliffs and beaches. This volume focuses on the coastal chalk cliffs of the English Channel, where a multidisciplinary approach has been used to understand active coastal cliff recession.
The book is organized around three main themes: the geological factors controlling cliff instability, the marine parameters influencing coastal erosion and the use of some new tools for hazard assessments.
This volume will be of use to academics and professionals working on rocky shores, with an interest in sedimentary geology, stratigraphy, tectonics, geomorphology, engineering geology, coastal engineering and GIS.