## 5 Discussion
### Implications for the Vanuatu Arc Volatile Budget  
Vanuatu hosts two of the largest volcanic gas emission sources globally. Ambrym, a volcanic island known for frequently hosting the lava lakes of Benbow and Marum until its 2018 eruption [61] appears first on the list of subaerial SO\({}_{2}\) emissions measured from space between 2005-2015 [23]. The 10-year averaged SO\({}_{2}\) emission inventory ranks Yasur volcano (located in the island of Tanna; see Figure 1) at number 11 in the list. Notably, Bagana, Tavurvur and Manam, from the nearby archipelago of Papua New Guinea, are all in the top 10. Clearly, the southwest pacific is a major contributor to global volcanic gas release. Vigorous volcanic SO\({}_{2}\) degassing in Vanuatu had been reported previously by [PERSON] et al. [36]. Using repeated DOAS (differential optical absorption spectroscopy) ground measurements (2004-2009) and satellite OMI data (2004-2011), ([PERSON] et al., 2012) estimated that on average 3 Tg y\({}^{-1}\) of volcanic SO\({}_{2}\) are emitted into the atmosphere along the Vanuatu arc, to which Ambrym reportedly contributed to about a third. Such estimates did not include sporadic eruptions and/or extreme passive degassing events, but nonetheless represented about one-fifth of currently estimated global volcanic SO\({}_{2}\) emissions. The study also marked the first ground-based SO\({}_{2}\) flux estimates for Mount Garet volcano. During October and December 2009, seven DOAS traverses yielded a mean SO\({}_{2}\) emission rate of \(\sim\)2959 t d\({}^{-1}\)[36]. These measurements were taken during the 2009-2010 eruption that started in September (see cfr. 2 for details) and most probably reflected the high degassing rates registered in the first few months of the eruption [36; 44]. In fact, [PERSON] et al. [23] found much lower SO\({}_{2}\) emission rates for the period of 2005-2015 at Gaua. They reported a 10-year maximum of \(\sim\)1418 t d\({}^{-1}\) in 2012, and a 10-year average of \(\sim\)434 t d\({}^{-1}\) of SO\({}_{2}\). Mismatches between ground and satellite-based emission inventories may arise from several factors [62]. Especially during the course of the 2009-2010 eruption (OMI satellite data yielded yearly averaged emissions of \(\sim\)490 and 605 t d\({}^{-1}\) for 2009 and 2010, respectively) [23], discrepancies may originate from difficulties in accurately measuring SO\({}_{2}\) in proximal ash-laden plumes, like the ones originated, for instance, in the explosive events of November 2009 [44]. Due to the low altitude of Mount Garet (\(\sim\)797 m a.s.l. ), it is also possible for some passive degassing emission rates measured via satellite to be underestimated. That is because the detection limit will be lowest for low-latitude volcanoes, which benefit from more satellite observations under optimal conditions (e.g., low solar zenith angles) [23; 62]. No SO\({}_{2}\) flux record was obtained during our 2018 survey. We therefore combine the 10-year (2005-2015) average volcanic SO\({}_{2}\) flux of [PERSON] et al. [23] with our in-situ measurements of volcanic gas compositions (2018) to estimate, for the first time, Mount Garet's emission inventory for H\({}_{2}\)O, CO\({}_{2}\), H\({}_{2}\)S and H\({}_{2}\). In doing so, we assume the 2005-2015 average [23] as the available best proxy for the characteristic SO\({}_{2}\) emission behavior during the volcano's persistent (yet quiescent) degassing behavior (as observed during our in-situ survey in 2018). Using Bani et al. [36] SO\({}_{2}\) flux dataset would have led to substantially higher fluxes, yet most likely biased due to the fact that the large pulses in SO\({}_{2}\) release in the Bani et al. [44] dataset correspond to degassing behaviors associated with the 2009-2010 explosive eruptions and are markedly distinct from the passive degassing observed in 2018.