Physical models of volcanic eruptions

Our present understanding of the dynamics of volcanic eruptions is summarized. A few important facts about volcanic eruptions are reviewed and outstanding problems are identified. Current research efforts are aimed at explaining why an eruption may alternate between, and pass through, different dynamical regimes. The basic physics of eruptions are explained from a dynamical point of view, with emphasis on the processes acting to fix the gas content of the erupted material. The coupling between flow processes and pressure release leads to large changes of decompression rate during ascent in a volcanic conduit. The decompression rate may reach very high values, which suggests that the kinetics of degassing play an important role. Accurate values of the solubility of the major magmatic volatile species are required at pressures of < 10 bar, as these play a major role in the final volume fraction of gas which is achieved at the eruptive vent, and even below 1 bar, as these dictate the behaviour of the erupted material in an atmospheric eruption column.