The 2007 caldera collapse of Piton de la Fournaise volcano: Source process from very-long-period seismic signals

Zacharie Duputel (1) , Luis Rivera (1)

1 IPGS-Sismologie - Sismologie (IPGS)

In April 2007, Piton de la Fournaise volcano experienced its largest caldera collapse in at least 300 yr. This event consisted of a series of 48 subsidence increments characterized by very-long-period (VLP) seismic signals equivalent to M w 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.

Mots clés: caldera collapse; magma reservoir processes; Piton de la Fournaise; single force source; surface waves

Domaines: Volcanologie; Géophysique [physics.geo-ph]; Tectonique

Zacharie Duputel, Luis Rivera. The 2007 caldera collapse of Piton de la Fournaise volcano: Source process from very-long-period seismic signals. Earth and Planetary Science Letters, 2019, 527 (10), pp.115786. ⟨10.1016/j.epsl.2019.115786⟩. ⟨hal-02324812⟩