Caldera rim collapse: A hidden volcanic hazard - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Volcanology and Geothermal Research Année : 2008

Caldera rim collapse: A hidden volcanic hazard

Olivier Merle
Laurent Michon
Patrick Bachèlery

Résumé

Following the emblematic flank collapse of Mount St Helens in 1981, numerous models of flank sliding have been proposed. These models have allowed to largely improve the understanding of mechanisms involved in such landslides, which represent a tremendous risk for populations living around volcanoes. In this article, a new mode of landslide formation, related to buried calderas, is described. The model emphasizes the paramount importance of the hidden ring fault that, even when the caldera is buried, still remains a plane of weakness in the core of the edifice. Under certain conditions, this plane of weakness becomes activated as the upper part of a pre-existing critical slip surface and is used in the emplacement of huge landslides which travel downslope at a very high velocity. A natural example is taken from Piton de la Fournaise Volcano (La Réunion Island, Indian Ocean). It reveals that the primary cause triggering caldera rim collapse is partial unbuttressing of the flank of the volcano. In the natural example, this occurs through regressive erosion that excavates deep canyon in the direction of the buried caldera but other mechanisms may exist. On account of the large volumes of material involved in caldera rim collapse as well as their long runout distances, such a volcanic hazard should be taken into account on every volcano where buried calderas are suspected.
Fichier principal
Vignette du fichier
2008-JVGR-2008_hal.pdf (1.24 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

hal-00373485 , version 1 (24-10-2016)

Identifiants

Citer

Olivier Merle, Laurent Michon, Patrick Bachèlery. Caldera rim collapse: A hidden volcanic hazard. Journal of Volcanology and Geothermal Research, 2008, 177 (2), pp.525-530. ⟨10.1016/j.jvolgeores.2008.06.011⟩. ⟨hal-00373485⟩
343 Consultations
183 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More