Behaviours of pyroclastic and analogue materials, in dry and wet environments, for use in experimental modelling of pyroclastic density currents

Modelling pyroclastic density currents (PDCs) is a challenging yet essential element of hazard assessment. PDCs are unpredictable and internal processes are often difficult to measure directly. Analogue experiments have been an important tool for investigating internal PDC dynamics. Typically, analogue experiments have removed moisture from experimental materials to limit cohesion. However, this does not well represent natural systems, where moisture can be introduced into a PDC. In this study, we investigate pyroclastic and analogue materials in dynamic (i.e., flowing), static (i.e., stationary), wet and dry experiments to explore fundamental behaviours. The addition of moisture can lead to fundamental changes in material properties resulting in significant impacts on geomechanical behaviours (size, density, internal friction angle), fluidisation and flowability. This work highlights the importance of validating the material choice used in modelling experiments, especially in wet conditions, and provides insights into flow dynamics of PDCs and depositional architecture of their deposits.