Experimental measurements of the viscosity and melt structure of alkali basalts at high pressure and temperature

Volcanic eruptions are shallow phenomena that represent the final stage of density- and viscositydriven
processes of melt migration from source rocks at upper mantle depths. In this experimental
study, we investigated the effect of pressure (0.7–7.0 GPa) and temperature (1335–2000 °C) on the
viscosity and the atomic melt structure of a synthetic anhydrous primitive alkaline basalt, an analogue
of the pre-eruptive magma that likely feeds the Campi Flegrei Volcanic District at present day.
Obtained viscosities (0.5–3.0 Pa s), mobility (0.1–0.4 g cm3
Pa−
1 s−
1) and ascent velocity (1.5–6.0 m yr−
1)
are presented to support geochemical and geophysical observations of Campi Flegrei as a critical
volcanic district currently undergoing gradual magma recharge at depth.