A model for viscous magma fragmentation during volcanic blasts

摘要: Fragmentation of magma containing gas bubbles is great interest in connection with developing models for the formation pyroclastics and volcanic blasts (explosions). This paper considers problem fragmentation highly viscous (η>108 Pa s) or solidified excess pressure. It suggested that be considered on basis wave theory proposed by Nikolsky Khristianovich, which generally applicable to gas-dynamic phenomena occurring mines. Then it becomes possible derive equations conservation front moves into a body from its free surface. As result, velocity, N, fragmentation, u, movement gas-pyroclastic mixture behind front, are determined. Calculations show N can reach ∼5 m/s. Therefore duration (blast duration) proves long. The model explains possibility several explosions during blast as result stopping, accounts angular shape pyroclasts brittle disruption interbubble partitions propagation through porous body. initiation cessation defined porosity, tensile strength, pressure differential between pores atmospheric physical developed mechanism energy release Vulcanian Pelean types.