Temporal Variability in Gas Emissions at Bagana Volcano Revealed by
Aerial, Ground, and Satellite Observations
Abstract
Bagana is a remote, highly active volcano, located on Bougainville
Island in southeastern Papua New Guinea. The volcano has exhibited
sustained and prodigious sulfur dioxide gas emissions in recent decades,
accompanied by frequent episodes of lava extrusion. The remote location
of Bagana and its persistent activity have made it a valuable case study
for satellite observations of active volcanism. This remoteness has also
left many features of Bagana relatively unexplored. Here, we present the
first measurements of volcanic gas composition, achieved by unoccupied
aerial system (UAS) flights through the volcano’s summit plume, and a
payload comprising a miniaturised MultiGAS. We combine our measurements
of molar CO2/SO2 ratio in the plume with
coincident remote sensing measurements (ground- and satellite-based) of
SO2 emission rate, to compute the first estimate of
CO2 flux at Bagana. We report low SO2
and CO2 fluxes at Bagana from our fieldwork in September
2019, ~320 ± 76 td-1 and
~320 ± 84 td-1 respectively, which we
attribute to the volcano’s low level of activity at the time of our
visit. We use satellite observations to demonstrate that Bagana’s
activity and emissions behaviour are highly variable and advance the
argument that such variability is likely an inherent feature of many
volcanoes worldwide and as yet is inadequately captured by our extant
volcanic gas inventories, which are often biased to sporadic
measurements. We argue that there is great value in the use of UAS
combined with MultiGAS-type instruments for remote monitoring of gas
emissions from other inaccessible volcanoes.