First estimate of volcanic SO2 budget for Vanuatu island arc

Abstract

International audienceThe spatial and temporal coverage of measurements of previous termvolcanicnext term gas emissions remains patchy. However, over the last decade, emissions inventories have improved thanks to new measurements of some of the lesser-known previous termvolcanicnext term areas. We report on one such region - the Vanuatu island arc, in the Southwest Pacific - for which we now have sufficient systematic observations to offer a systematic emissions inventory. Our new estimate is based on SO2 flux measurements made in the period 2004-2009 with ultraviolet spectroscopy techniques for the following volcanoes: Yasur, Lopevi, Ambrym, Ambae, Gaua and Vanua Lava (from south to north). These are the first ever measurements for Lopevi, Gaua and Vanua Lava. The results reveal the Vanuatu arc as one of Earth's prominent sources of previous termvolcanicnext term degassing with a characteristic annual emission to the atmosphere of ~ 3 Tg of SO2 (representing about 20% of hitherto published global estimates). Our new dataset highlights the sustained prodigious degassing of Ambrym volcano, whose 5 Gg d-1 mean flux of SO2 represents nearly two-thirds of the total budget for the Vanuatu arc. This confirms Ambrym as one of the largest previous termvolcanic sources worldwide comparable to Etna, often considered as the most vigorous source of previous termvolcanic emission on Earth. We also report a high degassing for Ambae of ~ 2 Gg d-1 SO2, representing more than 28 % of the Vanuatu arc budget. Thus, 90 % of the SO2 output from Vanuatu is focused in the central part of the arc (from Ambrym and Ambae) where magmas originate from enriched Indian-type mantle and where peculiar tectonic conditions could favour high magma production rates

Systematic satellite observations of the impact of aerosols from passive volcanic degassing on local cloud properties

“…Magmatic gases, mostly SO 2 , are continuously released from three vents in Yasur's crater and typically rise to heights of 700-900 m before being carried to the northwest by trade winds (Bani et al, 2012). Measurements made by Bani and Lardy (2007) and Bani et al (2012) The nearest other aerosol sources to Yasur are just under 400 km away, at the volcanoes of Lopevi (156 Mg day −1 SO 2 ) and Ambrym (5440 Mg day −1 SO 2 ) (Bani et al, 2012). Yasur is close to being a sea-level point SO 2 source, with a summit elevation of just 361 m. We therefore expect any orographic effects to be minimal.…”

“…seasonal average upwinddownwind difference of 0.03-0.06 for MODIS (Aqua); 0.02-0.03 for AATSR) downwind of Yasur, relative to that upwind. Ground-based SO 2 measurements at Yasur have been too infrequent (Bani et al, 2012) to allow a useful comparison with AOD retrieved from MODIS data. There is also a net difference in CER between the downwind and upwind sectors (seasonal average differences are −3-−4 µm, MODIS; 0-−4 µm AATSR).…”

First determination of magma-derived gas emissions from Bromo volcano, eastern Java (Indonesia)

“…For instance, Hilton et al (2002) estimated an Indonesian CO 2 flux of~0.36 Tg/yr that is poorly constrained from very few data. In summary, given the intense volcanic activity in Indonesia and the important gas emissions sustained by other arc segments in the southwest Pacific, such as Papua New Guinea (McGonigle et al, 2004;McCormick et al, 2012) and Vanuatu (Bani et al, 2012), increasing the data base for volcanic gas compositions and fluxes in Indonesia is essential to refining current global volcanic gas inventories (Hilton et al, 2002;Burton et al, 2013;Shinohara, 2013).…”

Sulfur dioxide emissions during the 2011 eruption of Shinmoedake volcano, Japan

“…At present, hand-held spectrometer-based systems have completely replaced the COSPEC. They are used at many volcanoes around the world (i.e., McGonigle et al, 2004;Oppenheimer et al, 2004;Mori et al, 2006a;Bani et al, 2012).…”