Soria-Hoyo C. auteur aut IRD Valverde J. M. auteur aut IRD Roche Olivier auteur aut IRD text journalArticle eng text/pdf born digital access The results of laboratory-scale experiments with ignimbrite material are reported and discussed. The ignimbrite material contained in a rotating drum is subjected to mechanical vibrations, simulating particle agitation at the base of a pyroclastic flow propagating on an irregular substrate. It is observed that vibrations lead to a severe decrease of internal friction, evidenced by a drastic drop of the avalanche angle of the material in the rotating drum. We propose that acoustic streaming, a well-known phenomenon in engineering applications, operates in the ignimbrite material. Vibrations cause the development of rotational air flow around the particles, and in consequence, the enhancement of hydrodynamic viscous stresses promotes pore fluid pressure, which leads to dynamical weakening through fluidization. A fluid mechanical theoretical model accounts for the decrease of the friction coefficient of the ignimbrite material under a wide range of experimental conditions. It can be reasonably inferred that sustained high gas pore pressure resulting from mechanical agitation could be present in pyroclastic flows and might contribute to their high mobility. specialized Pyroclastic flow Fluidization Acoustic streaming Pore pressure 066 020 81 2 art. 12 [12 ] 2019 0258-8900 https://www.documentation.ird.fr/hor/fdi:010075106 10.1007/s00445-019-1271-3 0258-8900 [F B010075106] https://www.documentation.ird.fr/hor/fdi:010075106 https://www.documentation.ird.fr/intranet/publi/2019/02/010075106.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2019-03-06 2025-02-24 fdi:010075106 fre