In many volcanic studies, estimates must be made of the changes that magma and its associated gases experience when traveling through an eruptive conduit to the surface. Exsolution of magmatic gas, acceleration, changes in pressure and temperature, depth of fragmentation, and final exit velocities affect such features as lava fountain heights, spatial distribution of eruptive products, and the degree to which water can enter the conduit during eruptive activity. Most of these quantities cannot be easily estimated without some sort of numerical model. -- Mastin, 1995 |