Abstract

The explosive eruption of a volcano that occurs when a volcanic canal is suddenly depressurized is one of the mysterious phenomena of nature, the mechanism of which is associated with the sudden decompression of a high-pressure magma containing dissolved gas and microcrystallites and with its transition to a multiphase state. With the obvious lack of the possibility to directly investigate these processes, the problem of experimental and numerical modeling, and creation of mathematical models that would allow describing the state of magma during various stages of eruption with a certain degree of adequacy are becoming topical. A model combining systems of equations of the mechanics of multiphase media is proposed. The model is formulated on the basis of the modified Iordansky–Kogarko–van Wijngaarden model with the Navier-Stokes equation for the variable viscosity, and the full range of kinetic relationships, including spontaneous nucleation and saturation dynamics of magma with cavitation nuclei. An analysis of a pre-explosive state of a number of volcanoes was carried out, which showed that the structural features of explosive volcanoes are analogous to the schemes of hydrodynamic shock tubes (UT), such as Glass-Heuckroth. Experimental modeling of the flow structure demonstrates the probability of the formation of the projectile regime as a consequence of coalescence of bubbles in the flow. A physical model of combined explosive volcanic eruptions is proposed; the process of formation in the magma flux of an independent flow of crystalline clusters (magmatic ”bombs“) moving with respect to the flow of cavitating magma at a much higher rate is experimentally studied.