The primary goal of this project is to develop a mathematical analysis and computer model of the movement of magma within volcanoes. Eruptions are normally driven by the growth of gas bubbles that come out of solution in the magma due to reductions in pressure before and during magma ascent within the volcano. The project consists of two parts. The first is a mathematical and computer analysis of volcanic eruption processes. The second is a sensitivity analysis to determine how the model system responds to variations in each of a number of attributes of the volcanic system. This should elucidate the roles and relative importance of all relevant factors in driving volcanic eruptions. The numerical model will enable us to explore the interaction of magma ascent, bubble growth, bubble size distribution, temperature change, and other specific volcanic processes. The proposed model is not intended to simulate specific natural eruptions. Rather, the results of the model and sensitivity study should lead to a better understanding of the mechanisms by which bubble growth drives eruptions, and an understanding of how magmatic conditions, properties, and conduit geometry affect the style of volcanic eruptions. This will set the stage for determining the conditions under which to expect explosive volcanic eruptions and their related volcanic hazards.