## 1 Introduction  
Monitoring the composition and mass flux of subaerial volcanic emissions is key to understanding how volcanism impacts our planet, on both local and global scales. At subduction zones, de-volatilization of subducting slab materials during high-pressure metamorphism [1; 2; 3] returns volatiles back to the hydrosphere-atmosphere via mantle wedge melting and arc volcanism. These materials are injected into the mantle through subducted sediments [4; 5; 6; 7], altered oceanic crust (AOC) [8; 9] and serpentinized lithospheric mantle [10; 11; 12]. Therefore, constraining major volatile budgets from subaerial volcanic arc emitters provides a tool to partially quantify the recycling efficiency of H\({}_{2}\)O, CO\({}_{2}\), SO\({}_{2}\) and other volatiles via the subduction process. The contrasting volatile ratios in the depleted mantle (CO\({}_{2}\)/S\({}_{\rm T}\) of \(\sim\)0.3-0.8) [13], subducted sediments (CO\({}_{2}\)/S\({}_{\rm T}\)\(\sim\)1-100) [14] and crustal fluids from limestone de-carbonatation (CO\({}_{2}\)/S\({}_{\rm T}\)\(>\)100) [15] imply that measuring volcanic gas composition can bear crucial information on volatile sources at depth. At the arc-scale, ever-increasing volcanic gas inventories are key to understanding the volatile cycle at subduction. However, global volcanic gas datasets [15; 16; 17; 18; 19; 20; 21; 22] are still sparse and incomplete, largely due to the remote location of some volcanic centers, inaccessibility, social/political instability of geographic regions and/or high level of volcanic activity. For instance, the Southwestern Pacific region is home to some of the most persistently degassing volcanoes on Earth [23], but Melanesian volcanoes have systematically been underrepresented in previous literature reviews. Recent advances in satellite remote sensing techniques, such as the ozone monitoring instrument (OMI), have greatly improved our knowledge on SO\({}_{2}\) flux emissions globally [23], revealing Vanaatu as a major volcanic SO\({}_{2}\) source globally, and urging the volcanic gas community to target volcanic gas studies in the poorly studied, yet strongly emitting volcanoes along this arc segment. In-situ measurements of volcanic gas compositions can be attained by using relatively inexpensive multi-component gas analyzer systems (such as the multi-GAS) [24; 25]. In addition to their great potential in eruption forecasting, these portable units have revolutionized our understanding of along-arc chemistry of volcanic gases at different regions of the world. Moreover, when combined with remotely sensed SO\({}_{2}\) fluxes, these measurements provide a means to constrain volcanic gas fluxes, especially CO\({}_{2}\)[17; 18; 19; 20; 21; 26; 27; 28; 29]. In the Vanaatu arc, volcanic gas surveys have mostly focused on Yasur [30; 31; 32] and Ambrym [33; 34; 35] due to the persistent high levels of degassing and volcanic activity. However, Reference [36] reported the first estimate of volcanic SO\({}_{2}\) budget for the Vanaatu Island Arc, in which the authors highlight other vigorously degassing volcanoes along the arc, for which volcanic gas compositions have remained unconstrained. In this paper, we present the results of a field campaign to measure gas compositions and estimate total volatile fluxes emitted from Mount Garet volcano (or Mount Gharat; also occasionally referred to in the literature as Gaua volcano), located on the island of Gaua, Vanaatu, whose activity in 2009-2010 prompted the evacuation of more than 1500 inhabitants [36]. Data collected in December 2018 is here integrated with previous SO\({}_{2}\) flux reports from both ground-based measurements [36] and satellite records [23] in order to assess the volatile budget of Mount Garet. Data from this study represents the first in-situ plume composition measurements obtained for Mount Garet and thus provides information on volcanic gas signatures in the northern part of the arc segment.