Effondrements des falaises crayeuses en Haute-Normandie

Abstract : The study is carried out in collaboration with the non-profit corporation, ESTRAN. Thanks to this original partnership, we have a remarkable and unique database describing 331 coastal chalk cliff falls from 2002 to 2009 along the chalk cliff line from Sainte-Marguerite-sur-Mer to Bracquemont (Upper Normandy, France). This database has numerous advantages: a long period of observation (8 years) and a high-periodicity of survey (every week). Spatial and temporal distributions of cliff falls highlight sensitive areas as Ailly cape and that cliff falls occur all year long. However, winter is the main season of cliff falls occurrence (in fallen volume and number of falls), then autumn and spring. Summer is not a season prone to cliff falls but some massive falls might occur. The statistical approach used in this study (P.C.A.) emphasizes that cliff fall is the result of a combination of processes. Marine processes seem mainly responsible for falls in winter, then in autumn and sub-aerial weathering processes seem predominant in summer, then in spring, but falls are less numerous and less massive. Statistical approach (fitting to a power law) provides answers about return periods of falls according to fallen volumes and spatial distributions. This statistical approach used in this study is only relevant if it is linked with geomorphologic approach in order to distinguish factors that trigger the fall.
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Conference papers
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https://hal.archives-ouvertes.fr/hal-00709654
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Submitted on : Tuesday, June 19, 2012 - 10:55:26 AM
Last modification on : Tuesday, August 27, 2019 - 11:02:09 AM

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  • HAL Id : hal-00709654, version 1

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Pauline Letortu, Stéphane Costa, Jean-Michel Cador, Hervé Quénol. Effondrements des falaises crayeuses en Haute-Normandie. XIIèmes Journées Nationales Génie Côtier - Génie Civil, Jun 2012, Cherbourg, France. pp.315-322. ⟨hal-00709654⟩

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