Autofluidization of pyroclastic flows propagating on rough substrates as shown by laboratory experiments - Université Clermont Auvergne Accéder directement au contenu
Article Dans Une Revue Journal of Geophysical Research Année : 2014

Autofluidization of pyroclastic flows propagating on rough substrates as shown by laboratory experiments

Résumé

This study investigates the influence of the substrate surface roughness on the emplacement mechanisms of pyroclastic flows. We carried out laboratory experiments on gravitational flows generated from the release of initially fluidized or nonfluidized columns of fine particles (diameter d = 0.08 mm) in a horizontal channel. The roughness of the channel base was uniform in each experiment, created by gluing particles of diameter d0 = 0.08 to 6 mm to the base. Other things being equal, the flow runout distance increased with the channel base roughness (d0) to a maximum of about twice that of flows on a smooth substrate when d0 = 1.5–3 mm, before decreasing moderately at higher roughness values of d0 = 6 mm. Long runout originated mainly during the late stages of emplacement as flow deceleration was strongly reduced at high substrate roughness. This was caused by (partial) autofluidization due to an upward air flux escaping from the substrate interstices in which flow particles settled. Autofluidization was evidenced by high pore fluid pressure measurements at the base of initially nonfluidized flows and also by reduced flow runout when the interstices were initially partially filled so that less air was available. Furthermore, the runout distance of flows of large particles (d = 0.35 mm), which could not be fluidized by the ascending air flux, was independent of the substrate roughness. This study suggests that autofluidization caused by air escape from the interstices of a rough substrate is one important mechanism to explain the common long runout distance of pyroclastic flows even on subhorizontal topographies.

Domaines

Volcanologie
Fichier principal
Vignette du fichier
2013JB010554.pdf (2.33 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-01133677 , version 1 (12-11-2021)

Licence

Copyright (Tous droits réservés)

Identifiants

Citer

Corentin Chedeville, Olivier Roche. Autofluidization of pyroclastic flows propagating on rough substrates as shown by laboratory experiments. Journal of Geophysical Research, 2014, 119, pp.1764-1776. ⟨10.1002/2013JB010554⟩. ⟨hal-01133677⟩
59 Consultations
16 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More