CO2 flushing triggers large eruptions at open conduit volcanoes: The case of Stromboli

Open conduit volcanoes, of which Stromboli is an emblematic example, erupt with the highest frequency on Earth. The activity at Stromboli is characterised by frequent small explosions intercalated by larger events that pose a significant risk to local populations, tourists, and scientists. Thus, identifying the signs of an impending larger explosion is of outmost importance for the mitigation of volcanic hazard. Here we show that the interaction between CO2-rich fluids and magma leads to the accumulation of volatile-rich, low-density magma at depth without the requirement of a permeability barrier:CO2-flushing forces the exsolution of water and the increase of magma viscosity, which proceeds from the bottom of the plumbing system upwards. This rheological configuration leads to the progressive thickening of a gas-rich, low density and gravitationally unstable layer at the bottom of the volcanic plumbing system. Our calculations account for gas monitoring data and provide a base to track the approach to deeply triggered large or paroxysmal eruptions and estimate their size from continuous gas monitoring data. The model we propose for Stromboli can be applied to any other open conduit volcanoes globally and offers a framework to anticipate the occurrence of unexpectedly large eruptions.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)