Electrical conductivity measurements of rhyolitic glass at high pressure and high temperature

We performed electrical conductivity measurements of rhyolite glasses across the glass transition temperature at 1 GPa. Our experimental data show that, in the Arrhenius plot, the conductivity of rhyolite with 0.2 wt% H2O has an inflection point between around 760 K, while for rhyolite with 4.9 wt% H2O the gradient changes between 685 and 825 K. These inflection points correlate with the glass transition temperature, and are compared with results of previous experiments. The degree of welding of clastic and hydrous rock can be constrained by estimating glass transition temperatures of volcanic rocks combined with measurements of electrical conductivity structures obtained from electromagnetic soundings beneath volcanic bodies. This, in turn, can be used to aid predictions of volcanic eruption.