@article{fdi:010067617, title = {{D}egassing dynamics of basaltic lava lake at a top-ranking volatile emitter : {A}mbrym volcano, {V}anuatu arc}, author = {{A}llard, {P}. and {B}urton, {M}. and {S}awyer, {G}. and {B}ani, {P}hilipson}, editor = {}, language = {{ENG}}, abstract = {{P}ersistent lava lakes are rare on {E}arth and provide volcanologists with a remarkable opportunity to directly investigate magma dynamics and degassing at the open air. {A}mbrym volcano, in {V}anuatu, is one of the very few basaltic arc volcanoes displaying such an activity and voluminous gas emission, but whose study has long remained hampered by challenging accessibility. {H}ere we report the first high temporal resolution (every 5 s) measurements of vigorous lava lake degassing inside its 300 m deep {B}enbow crater using {OP}-{FTIR} spectroscopy. {O}ur results reveal a highly dynamic degassing pattern involving (i) recurrent (100-200 s) short-period oscillations of the volcanic gas composition and temperature, correlating with pulsated gas emission and sourced in the upper part of the lava lake, (ii) a continuous long period (similar to 8 min) modulation probably due to the influx of fresh magma at the bottom of the lake, and (iii) discrete {CO}2 spike events occurring in coincidence with the sequential bursting of meter-sized bubbles, which indicates the separate ascent of large gas bubbles or slugs in a feeder conduit with estimated diameter of 6 +/- 1 m. {T}his complex degassing pattern, measured with unprecedented detail and involving both coupled and decoupled magma-gas ascent over short time scales, markedly differs from that of quieter lava lakes at {E}rebus and {K}ilauea. {I}t can be accounted for by a modest size of {B}enbow lava lake and its very high basalt supply rate (similar to 20 m(3) s(-1)), favouring its rapid overturn and renewal. {W}e verify a typical basaltic arc signature for {A}mbrym volcanic gas and, based on contemporaneous {SO}2 flux measurements, we evaluate huge emission rates of 160 {G}g d(-1) of {H}2{O}, similar to 10 {G}g d(-1) of {CO}2 and similar to 8 {G}g d(-1) of total acid gas ({SO}2, {HC}l and {HF}) during medium activity of the volcano in 2008. {S}uch rates make {A}mbrym one of the three most powerful volcanic gas emitters at global scale, whose atmospheric impact at local and regional scale may be considerable.}, keywords = {{A}mbrym ; lava lake ; infrared spectroscopy ; volcanic gases ; magma ; degassing dynamics ; volatile fluxes ; {VANUATU}}, booktitle = {}, journal = {{E}arth and {P}lanetary {S}cience {L}etters}, volume = {448}, numero = {}, pages = {69--80}, ISSN = {0012-821{X}}, year = {2016}, DOI = {10.1016/j.epsl.2016.05.014}, URL = {https://www.documentation.ird.fr/hor/fdi:010067617}, }