Magma transfer and degassing budget: Application to the 2009-2010 eruptive crisis of Mt Garet (Vanuatu arc)

We suggest here the 2009-2010 activity to be sustained by the existence of thermal convection driven at the bottom of the magma reservoir by cooling, and in which the bubbles are small enough to be stagnant. The most energetic phases are better explained by an additional gas volume, associated to the crystallization of titanomagnetite microcrysts which significantly enhance bubble nucleation. The ultimate step of crystal growth prior to eruption suggests magma ascent within few hours.