Gas regime defining the mechanism of periodic lava fountaining of basaltic volcanoes (experimental modeling)

Abstract

Processes determining periodic fountaining of basaltic volcanoes were studied using our Complex apparatus for modeling basaltic eruptions - CAMBE [Ozerov, 2007]. It is 18 m high and consists of modeling and recording systems. When creating the Complex, geometric parameters ratio in the actual feeding system of basaltic Klyuchevskoy volcano was considered (taken as etalon); so the ration of CAMBE’s channel diameter to its height is ~ 1:1000. Formation and transformation of gas structures occurring when gas bubbles pass through up liquids of various densities have been studied. Experiments revealed a new mode of two-phase mixtures (gas-liquid) flow in vertical column – mode of free bubble clusters characterized by regular alteration of gas bubbles assemblages (clusters) isolated by liquid not containing free gas phase. Comparison of CAMBE acoustic records with diagrams of Klyuchevskoy volcanic tremor showed good correlation between modeled and natural data. Results obtained allowed suggesting a new pattern for gas-hydrodynamic migration of magmatic melt in the supply channel, where the regime of open gas clusters accounts for periodic fountaining of incandescent bombs during basaltic volcanoes eruptions.