SILICIC EXPLOSIVE VOLCANISM: MODALITIES OF MAGMA ...

Raffaello Cioni – Silicic explosive volcanism – GEOITALIA 2009 – Rimini 7-8 settembreCompeting rates of processes at eruptionEruption processes are dominated by the simultaneousvariation of multiple parameters, with differentcharacteristic rates Magma ascent (mm s -1 to m s -1 ) Volatile diffusion (10 -10 m 2 s -1 ) Crystal nucleation (10 2 -10 5 mm -3 s -1 ) and growth (10 -8 mm s -1 ) Bubble ascent (mm s -1 to m s -1 ) Permeable flow through magma (10 -12 m 2 ) and conduit walls(10 -16 m 2 ) Characteristic times for Strain rate (10 -1 s) vs. viscousrelaxation of the melt (10 -3 s)Raffaello Cioni – Silicic explosive volcanism – GEOITALIA 2009 – Rimini 7-8 settembreSilicic explosive eruptions