Roche Olivier, Phillips J.C., Kelfoun Karim. (2013). Pyroclastic density currents. In :
Fagents S.A. (ed.), Gregg T.K.P. (ed.), Lopes R.M.C. (ed.). Modeling volcanic processes : : the physics and mathematics of volcanism. Cambridge : Cambridge University Press, p. 203-229. ISBN 978-0-521-89543-9.
Titre du document
Pyroclastic density currents
Année de publication
2013
Type de document
Partie d'ouvrage
Auteurs
Roche Olivier, Phillips J.C., Kelfoun Karim
In
Fagents S.A. (ed.), Gregg T.K.P. (ed.), Lopes R.M.C. (ed.), Modeling volcanic processes : : the physics and mathematics of volcanism
Source
Cambridge : Cambridge University Press, 2013,
p. 203-229 ISBN 978-0-521-89543-9
This chapter summarizes the principal experimental and theoretical approaches used to investigate the physics of pyroclastic density currents (PDCs), which are gravity driven hot gas–particle mixtures commonly generated during explosive volcanic eruptions. PDC behavior ranges from pyroclastic surges, which are dilute turbulent suspensions, to pyroclastic flows, which are dense (fluidized) granular avalanches. Most PDCs consist of a coupled basal flow and an overriding surge, which renders their physics particularly complex. Experiments and phenomenological theory have been used to characterize the propagation and deposition mechanisms of PDCs. Most work has used turbulent gravity currents as an analogue to dilute PDCs and has provided fundamental insight into propagation and deposition dynamics and mixing with their surroundings. Dense PDCs have been investigated as granular and fluidized flows, and these studies have provided insight into deposit levée-channel morphology typical of coarse-grained flows, shown that fines-rich flows may behave as inertial fluid currents, and suggested that deposits of PDCs may form by aggradation. Numerical formulations ranging from continuum depth-averaged to discrete element models have been used to simulate PDC emplacement on real topographies and are fundamental in the context of volcanic hazard assessment and mitigation.
