000003512 001__ 3512
000003512 005__ 20180212113807.0
000003512 0247_ $$2DOI$$a10.1016/j.geomorph.2018.01.030
000003512 037__ $$aSCART-2018-0038
000003512 100__ $$aCamelbeeck, Thierry
000003512 245__ $$aEarthquakes as collapse precursors at the Han-sur-Lesse cave in the Belgian Ardennes
000003512 260__ $$c2018
000003512 520__ $$aCollapse activation is an ongoing process in the evolution of karstic networks related to the weakening of cave vaults. Because collapses are infrequent, few have been directly observed, making it challenging to evaluate the role of external processes in their initiation and triggering. Here, we study the two most recent collapses in the Dôme chamber of the Han-sur-Lesse cave (Belgian Ardenne) that occurred on or shortly after 3rd December 1828 and between the 13th and 14th of March 1984. Because of the low probability that the two earthquakes that generated the strongest ground motions in Han-sur-Lesse since 1800, on 23rd February 1828 (Mw=5.1 in Central Belgium) and 8th November 1983 (Mw=4.8 in Liège) occurred by coincidence less than one year before these collapses, we suggest that the collapses are related to these earthquakes. We argue that the earthquakes accelerated the cave vault instability, leading to the collapses by the action of other factors weakening the host rock. In particular, the 1828 collapse was likely triggered by a smaller Mw=4.2 nearby earthquake. The 1984 collapse followed two months of heavy rainfall that would have increased water infiltration and pressure in the rock mass favouring destabilization of the cave ceiling. Lamina counting of a stalagmite growing on the 1828 debris dates the collapse at 1826±9 AD, demonstrating the possibility of dating previous collapses with a few years of uncertain-ty. Furthermore, our study opens new perspectives for studying collapses and their chronology both in the Han-sur-Lesse cave and in other karstic networks. We suggest that earthquake activity could play a stronger role than previously thought in initiating cave collapses.
000003512 594__ $$aNO
000003512 6531_ $$aHistorical collapses in Han-sur-Lesse cave would have been promoted by earthquakes
000003512 6531_ $$aA methodology for dating ancient breakdowns in caves is validated
000003512 6531_ $$aSeismicity role in cave room evolution may be  stronger than previously thought 
000003512 700__ $$aQuinif, Yves
000003512 700__ $$aVerheyden, Sophie
000003512 700__ $$aVanneste, Kris
000003512 700__ $$aKnuts, Elisabeth
000003512 773__ $$c13-24$$pGeomorphology$$v308$$y2018
000003512 8560_ $$fthierry.camelbeeck@observatoire.be
000003512 905__ $$apublished in
000003512 980__ $$aREFERD