Fig. 5: Emanation coefficients (ε) compared for a selection of volcanoes.

Emanation coefficients at a selection of basaltic to basaltic-andesite intraplate and arc volcanoes, ordered to their magnitude in Kīlauea 2018 (average of two ground samples). All emanation coefficients are calculated using X/SO₂ ratios as outlined in ‘Methods’, with the exception of Holuhraun, for which the values are those given in the paper, calculated using \({{\boldsymbol{\varepsilon }}}_{{\boldsymbol{Pb}}}\). Data sources are as in Fig. 4, in addition to a study of degassed and undegassed melts⁵³, and a compilation (Rubin) of ε at a mixture of tectonic settings⁷². Data for the figure can be found in Supplementary Data 1 Table S16 and a description of ε calculations can be found in ‘Methods’. Error bars represent the emanation coefficients calculated for the maximum and minimum X/SO₂ ratio measured during each measurement campaign. Errors are not available for the Rubin compilation⁷² or the Holuhraun 2014–2015 data¹¹.