Zacharie Duputel, Luis Rivera

In April 2007, Piton de la Fournaise volcano experienced its largest caldera collapse in at least 300 years. This event consisted of a series of 48 subsidence increments characterized by very-long-period (VLP) seismic signals equivalent to Mw 4.4 to 5.4. Source analysis of VLP events suggests a piston-like mechanism with a collapsing crack source corresponding to the contraction of the magma reservoir and a single force representing the collapse of the above rock column. We show that the collapse dynamics is primarily controlled by magma withdrawal from the reservoir, which was likely in a bubbly state at the time of the event. Similar to the 2018 Kilauea collapse, we observe a reduction of the time-interval between successive subsidence increments, which results from the acceleration of magma withdrawal and a progressive weakening of the edifice at the beginning of the sequence.