Volcanic spreading and slope stability ranges from slow and continuous to sudden and catastrophic, actually representing the most energetic and dangerous volcanic phenomena; it is often observed at volcanoes and the interpretation of such events is challenged by the complex and evolving interactions between tectonic, magmatic, fluid, and gravitational processes. Flank motion produces continuous creep and faulting that affect the volcano periphery. Rock-falls, frequently evolving in gravel flows or rock avalanches, are often associated with volcanic activity. In most cases, volcano slopes continue below the sea level and also subaqueous volcano flanks can be prone for mass wasting, often affected by terrestrial volcano built-up and activity. Dyke intrusions can provide additional horizontal stress promoting flank instability and failure. Explosive eruptions can severely disrupt the environment around volcanoes by depositing large volumes of erodible fragmental material, generating lahars. All these events potentially cause severe damage to human society, directly or through secondary events like tsunamis. Successful strategies for mass-wasting hazard assessment and risk reduction would imply integrated methodology for instability detection, mapping, monitoring and forecasting. Nevertheless, only few studies exist to date in which numerical modelling integrate geological, geophysical, geodetic studies with the aim of understanding and managing of terrestrial and subaqueous volcano slope instability.

This session invites research efforts that observe, quantify, or model volcano slope movements and failure. We encourage multidisciplinary contributions that integrate field-based on-shore and submarine studies (geological, geochemical), geomorphological mapping and account collection, with advanced techniques, as remote sensing data analysis, geophysical investigations, ground-based monitoring systems, and numerical and analogical modelling of volcano spreading, slope stability and runout volcaniclastic flows.