Mass-wasting in volcanic environment, both on-shore and subaqueous, comprises a wide spectrum of phenomena, from large lateral collapse to shallow debris remobilization that represent a major threaten for societies. Slope stability ranges from slow and continuous to sudden and catastrophic and the interpretation of such events is challenged by the complex and evolving interactions between tectonic, magmatic, fluid, and gravitational processes. The moving masses can behave in different ways depending on water content and flow rheology and can demonstrate different modes from flank spreading or collapse to granular or viscous flow. Water plays an important role in the transport and emplacement mechanisms of the flows, enhancing their run-out and destructive power. Many volcanoes worldwide are located in tropical, high-precipitation environments or are covered by snow or glaciers, which exacerbates the potential for landslides, lahars and debris avalanches. In most cases, volcano slopes continue below sea level and also subaqueous volcano flanks can be prone to mass wasting, often affected by terrestrial volcano built-up and activity. This session encourages multidisciplinary contributions from both earth and social scientists that critique,explain and discuss how high-resolution vulnerability and risk analysis and volcanic mass flow studies are necessary to reduce disaster risk within vulnerable populations. We expect contributions that integrate field-based geological and geochemical studies, geomorphological mapping, geophysical investigations,remote sensing and analytical, numerical and analogical modelling.