Insights into sub-surface magmatic processes from analysis of satellite volcanic plume imagery

Abstract:

Magmatic processes control volcanic eruptions through the interplay of degassing, rheology, plumbing geometry, and chemistry. We have achieved fantastic new insights into magmatic processes by examining crystal chemistry to determine timescales of processes and melt inclusions to determine volatile abundances. Numerical modelling of magma ascent is advancing rapidly, with ever more quantitative constraints on crystal kinetics from in-situ experiments.

Perhaps though we have been missing key constraints when trying to unravel the magmatic processes which drive volcanism: the temporal evolution of gas emissions before, during, and after major explosive eruptions. Gas emission time series are remarkably difficult to measure from the ground during major eruptions because the local monitoring networks are optimised for low-altitude, ash-free plumes and modest gas emissions rates. Instead, eruptions are typified by ash-rich, high-altitude plumes and very high gas emission rates.

We have been working now for several years now on the development of tools which allow the time series of SO₂ flux to be accurately quantified from single images of SO₂ column amounts measured from space. The key here is that a single image can be seen as tape recording of the volcanic gas emissions. Using back-trajectory modelling we can reconstruct the age and altitude of each gas-rich pixel. The altitude provides essential information both on the mass eruption rate and on the SO₂ quantification, whose retrieved amount is altitude dependent. Together, the time series of mass eruption rate and gas emission rate provide unprecedented constraints on the magmatic processes driving eruptive activity.

In this contribution we present the state of the art in flux and eruption rate time series evolution and examine the new insights into magmatic processes arising from these new data sources.