Fluid/Melt Partition Coefficients Of Halogens In Basaltic Melt

Pressurization vs. flushing in the modelling of volcanic gases at basaltic volcanoes

When modelling the composition of chemical gases released at basaltic volcanoes, two end-member processes can be quantitatively constrained by means of thermochemical techniques: closed-system magma degassing or, alternatively, the ascent of gas-bubbles, separated from the reservoir melt at some depth and flushing through the surrounding melt up to surface. In the first scenario, the ascent of volatile-rich (bubbles+melt) magmas from the reservoir is followed by gas/melt separation and fast ascent of the gas phase without any further re-equilibration with the residual melt filling the shallower conduit system. The features of this mechanism must be realized within the lumped approximation i…

Turmoil at Turrialba Volcano (Costa Rica): Degassing and eruptive processes inferred from high-frequency gas monitoring.

Abstract Eruptive activity at Turrialba Volcano (Costa Rica) has escalated significantly since 2014, causing airport and school closures in the capital city of San José. Whether or not new magma is involved in the current unrest seems probable but remains a matter of debate as ash deposits are dominated by hydrothermal material. Here we use high‐frequency gas monitoring to track the behavior of the volcano between 2014 and 2015 and to decipher magmatic versus hydrothermal contributions to the eruptions. Pulses of deeply derived CO2‐rich gas (CO2/Stotal > 4.5) precede explosive activity, providing a clear precursor to eruptive periods that occurs up to 2 weeks before eruptions, which are acc…