Deposits related to degradation processes on Piton des Neiges Volcano (Reunion Island): overview and geological hazard |
| |
| Authors: | Laurent Bret Yannick Fevre Jean-Lambert Join Bernard Robineau Patrick Bachelery |
| |
| Institution: | Laboratoire des Sciences de la Terre, Université de la Réunion, 15 avenue René Cassin, P.O.Box 7151, 97715, Saint Denis messag cedex 9, France |
| |
| Abstract: | Piton des Neiges (PN) Volcano on Reunion Island offers a rare opportunity to study deposits related to degradation processes in a deeply eroded oceanic shield volcano. Both the inner parts and flanks reveal a large amount of resedimented volcaniclastic material, including extensive debris avalanche deposits. PN litho–structural units, first studied by Upton and Wadsworth 1965, Philos. Trans. R. Soc. Lond., A 271, pp. 105–130], are re-examined. This review highlights the importance of long volcanic repose periods and erosion processes during PN history. volcaniclastic deposits have been studied in the field in order to evaluate the spatial and temporal distribution of the three main types of PN degradation processes. The deposits of these processes have been classified into: (1) talus, (2) mudflow and debris flow, and (3) debris avalanche. Lithology, frequency and estimated volumes of each deposit type imply that the structural evolution of PN can be considered in terms of the competition between the volcanic productivity and the degradation and erosion processes. The occurrence of huge catastrophic avalanches produced by flank failure is convincingly linked to the basaltic activity of PN, which implies a very low risk at present. On the contrary, mudflows and debris flows pose an important risk due to the high population density focussed around the basin outlets. Moreover, if smaller debris avalanches can occur in the cirques of PN, another major risk must be evaluated. |
| |
| Keywords: | Reunion Island Piton des Neiges breccia degradation erosion risk |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
