This session concerns the measuring and modelling of eruption dynamics, volcanic products and magmatic volatiles. The dynamics of shallow magma storage/ascent, volcanic plumes and pyroclastic density currents remains largely qualitative and only partially understood. Erupting volcanoes are highly complex and non-linear systems that represent a real challenge for quantitative description. Major progress has been recently made due to the availability of remote sensing techniques able to measure many physical and chemical eruptive variables, with important implications for conduit and plume dynamics. Advanced techniques of petrological, chemical, isotopic and textural characterization of pyroclasts and magmatic volatiles can provide detailed information on the initial state and evolution of the erupted products, and techniques of mathematical inversion of field data are becoming increasingly sophisticated. Physico-mathematical models and laboratory experiments allow us to simulate transient flow and fragmentation in conduits, volcanic plumes and pyroclastic density currents, even in three-dimensions. Validation of these models as well as the development of appropriate scaling laws are fundamental steps to increase our level of understanding. The session aims to bring together scientists using a range of field, petrological, geochemical and modelling techniques to characterise (1) volcanic plumbing systems and conduits immediately prior to, and during, eruptions, (2) the dynamics of volcanic plumes and pyroclastic density currents, (3) volcanic ash as an agent in Earth systems, (4) volcanic volatiles and their link to volcanic gas emissions, and (5) the sources, processes, and budgets of magmatic degassing. The session includes the 2011 Robert Wilhelm Bunsen Medal Lecture.