As magmatic and hydrothermal systems evolve, their interactions with surface and groundwater can generate explosions, explosive eruptions, hazardous gas emissions, lahars, and long-lived environmental and ecological impacts. Volcanic lakes represent dynamic interfaces between subsurface processes and the atmosphere, recording changes in magmatic input, hydrothermal circulation, and volatile fluxes. Hydrovolcanic activity, including phreatic, phreatomagmatic, and limnic eruptions, remains difficult to anticipate yet poses significant hazards. This session highlights advances in understanding magma–water interactions across volcanic and hydrothermal systems, with emphasis on the physical and chemical processes governing volcanic lake dynamics, hydrothermal alteration, geysers, and eruption or explosion triggering. We invite contributions using field observations, laboratory experiments, remote sensing, geochemical datasets, and numerical modeling, particularly those that improve monitoring, hazard assessment, and forecasting of hydrovolcanic activity.

• H - Hydrology
• NS - Near Surface Geophysics
• T - Tectonophysics