The collapses of cliff
The collapses questioning brutally hundreds or thousands of tons of rocks are not rare. The print, television media, the blog of the Foreshore Quoted from the Sea, the site of Norman and Geology, Sciences the Gyrodus association, or still report BRGM them tell because they have a spectacular character, although rarely mortal. They can again occur on steep slopes inside lands being the object of reports of the BRGM.
The forecast of the collapses of the rocky cliffs is rather random. The visual inspection sometimes allows to detect potentially dangerous fractures, but these can remain inactive during decades. The digital modelling allows to encircle the chance.
A census made every week by the Littoral Service of the association FORESHORE of Dieppe allows to raise a mapping of the importance of the collapses, resumed by the researchers of the universities of Caen and Rennes 2.
Various techniques geophysics was tested to determine the state of mechanical fragility and susceptibility to the collapse of rock massifs:
The last two techniques were implemented on the site of Mesnil-valley.
To date, as for earthquakes, there is no technique which allows to predict a short-term collapse.
We shall here content with bringing back some examples for which we have photos taken before and after the event.