Combined ground and aerial measurements resolve vent-specific gas fluxes from a multi-vent volcano

T D Pering,A J S Mcgonigle,T Richardson,K Wood,A Aiuppa,G Tamburello,T C Wilkes,E J Liu,M Bitetto

doi:10.1038/s41467-020-16862-w

Abstract

Volcanoes with multiple summit vents present a methodological challenge for determining vent-specific gas emissions. Here, using a novel approach combining multiple ultraviolet cameras with synchronous aerial measurements, we calculate vent-specific gas compositions and fluxes for Stromboli volcano. Emissions from vent areas are spatially heterogeneous in composition and emission rate, with the central vent area dominating passive emissions, despite exhibiting the least explosive behaviour. Vents exhibiting Strombolian explosions emit low to negligible passive fluxes and are CO2-dominated, even during passive degassing. We propose a model for the conduit system based on contrasting rheological properties between vent areas. Our methodology has advantages for resolving contrasting outgassing dynamics given that measured bulk plume compositions are often intermediate between those of the distinct vent areas. We therefore emphasise the need for a vent-specific approach at multi-vent volcanoes and suggest that our approach could provide a transformative advance in volcano monitoring applications.

Highlights

Volcanoes with multiple summit vents present a methodological challenge for determining vent-specific gas emissions
The on-going development of Unoccupied Aerial System (UAS)-mounted gas sampling enables in situ aerial measurements of gas concentrations in remote, high altitude or otherwise inaccessible volcanic plumes[30,33,34,35,36,37] with increased spatial resolution and reduced costs/logistics compared to conventional aircraft surveys[14]
We find that molar gas ratios during non-explosive passive degassing vary considerably between the different vent areas but are consistent for a specific vent between multiple flights

Summary

Introduction

Volcanoes with multiple summit vents present a methodological challenge for determining vent-specific gas emissions. Only bulk plume measurements are recorded and the contribution of each vent to the overall degassing flux remains unconstrained This uncertainty is problematic when different vents are characterised by contrasting eruptive behaviours and degassing styles, and likely exhibit distinct gas signatures. The on-going development of Unoccupied Aerial System (UAS)-mounted gas sampling enables in situ aerial measurements of gas concentrations in remote, high altitude or otherwise inaccessible volcanic plumes[30,33,34,35,36,37] with increased spatial resolution and reduced costs/logistics compared to conventional aircraft surveys[14] Until now, this UAS approach has yet to be integrated synchronously with the ground-based instrumentation needed to derive contemporaneous fluxes for all gas species in a multi-vent setting. By isolating gas compositions and emission rates from distinct degassing centres, and interpreting these data in the context of published constraints from other geophysical parameters, we contribute further insight into the shallow degassing processes and drivers of Strombolian explosions at this volcano

Methods

Results

Conclusion