Moussallam Yves auteur aut IRD Rose-Koga E. F. auteur aut IRD Koga K. T. auteur aut IRD Medard E. auteur aut IRD Bani Philipson auteur aut IRD Devidal J. L. auteur aut IRD Tari D. auteur aut IRD text journalArticle eng text/pdf born digital access In September 2017, after more than a hundred years of quiescence, Ambae (Aoba), Vanuatu's largest volcano, entered a new phase of eruptive activity, triggering the evacuation of the island's 11,000 inhabitants resulting in the largest volcanic disaster in the country's history. Three subsequent eruptive phases in November 2017, March 2018, and July 2018 expelled some of the largest tropospheric and stratospheric SO2 clouds observed in the last decade. Here, we investigate the mechanisms and dynamics of this eruption. We use major elements, trace elements, and volatiles in olivine and clinopyroxene hosted melt inclusions, embayments, crystals, and matrix glasses together with clinopyroxene geobarometry and olivine, plagioclase, and clinopyroxene geothermometry to reconstruct the physical and chemical evolution of the magma, as it ascends to the surface. Volatile elements in melt inclusions and geobarometry data suggest that the magma originated from depth of 14 km before residing at shallow ( 0.5 to 3 km) levels. Magma ascent to the surface was likely facilitated by shallow phreatic eruptions that opened a pathway for magma to ascend. Succeeding eruptive phases are characterised by increasingly primitive compositions with evidence of small amounts of mixing having taken place. Mg-Fe exchange diffusion modelling yields olivine residence times in the magma chamber ranging from a few days to a year prior to eruption. Diffusion modelling of volatiles along embayments (melt channels) from the first two phases of activity and microlite number density suggests rapid magma ascent in the range of 15-270 km/h, 4-75 m/s (decompression rates of 0.1 to 2 MPa/s) corresponding to a short travel time between the top of the shallow reservoir and the surface of less than 2 min. specialized Volatile Melt inclusion Magma ascent Basaltic eruption Geo-speedometer VANUATU AMBAE VOLCAN 066 064 174 11 art. 90 [24p.] 2019 0010-7999 https://www.documentation.ird.fr/hor/fdi:010077140 10.1007/s00410-019-1625-z 0010-7999 [F B010077140] https://www.documentation.ird.fr/hor/fdi:010077140 https://www.documentation.ird.fr/intranet/publi/2019/11/010077140.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2019-12-12 2025-02-24 fdi:010077140 fre