Shock-tube experiments and high-speed Schlieren shadow photography for low viscosity analogue materials

Volcanic eruptions show a wide range of eruptive stiles, from low intensity effusive eruption to energetic and powerful explosive eruptions. Different styles of activity can be also seen during the same volcanic eruption, particularly when low viscosity magmas, such as basalts, are involved. Yet, the conditions by which fragmentation of basaltic magmas is achieved (and thus the generation of explosive eruption) are not fully understood. This poses a real challenge to policymakers tasked with mitigating the risks associated with eruptions of basaltic volcanoes. In order to better understand the fragmentation of low viscosity magma, we employed a brand new apparatus combining a shock-tube apparatus together with a high-speed Schlieren shadow photography and acoustic sensors. We present preliminary results obtained with this new apparatus performing experiments either with water or different analogue materials. We performed experiments varying also parameters, such as the length and the diameter of the conduit, the fractal dimension of the tube and the pressure gradient.