Petrophysical characterisation of volcanic ejecta to constrain subsurface lithological heterogeneities: implications for edifice stability at basaltic volcanoes

Piton de la Fournaise (PdF) is a basaltic volcano whose activity characterized by effusive to mildly explosive eruptions. The geologic record preserves evidence of eruptions associated with the seaward sliding steep east flank. Such formed calderas that are several km in diameter and their products have been emplaced as breccias. breccias PdF offer opportunity sample wide range different lithologies covering most stratigraphy edifice. Petrophysical measurements revealed corresponding variability density, porosity, P-wave velocity, uniaxial compressive strength, confirming petrophysical consequences lithological diversity.  Different cannot simply be distinguished on basis physical properties. We infer instability should not interpreted solely terms altered rock units. large heterogeneity crustal rocks must considered when interpreting monitoring data assessing hazards related stability.