Long- and Short-Term Magmatic Behavior of Piton De La Fournaise Volcano Inferred from Noise-Based Seismic Monitoring

Thursday, 18 December 2014: 11:05 AM
Florent Brenguier1, Diane N Rivet2, Philippe Kowalski2, Eric Francois Larose3, Thomas Lecocq4, Julien A Chaput1, Serge Rambaud5, Nikolai Shapiro6, Michel Campillo1, Philippe Roux3, Valerie Ferrazzini2 and Nicolas Villeneuve2, (1)University Joseph Fourier Grenoble, Grenboble, France, (2)Institut de Physique du Globe de Paris, Paris, France, (3)ISTerre Institute of Earth Sciences, Saint Martin d'Hères, France, (4)Royal Observatory of Belgium, Brussels, Belgium, (5)Fairfield Industries, Sugar Land, TX, United States, (6)Institut de Physique du Globe, Paris, France
Probing the long-term preparation of eruptions as well as the short-term initiation and transport of magma to surface remains extremely difficult. One reason is that it is hardly possible to directly monitor at depth the magma storage area. One way to overcome this issue is to use seismic waves that, through their propagation, sample the targets of interest. Here we use ambient seismic waves to infer temporal mechanical property changes of Piton de la Fournaise volcano (PdF, La Réunion island). We find both 1) a long-term behavior that might reflect processes of deep magma replenishment as well as 2) short-term variations that are controlled by both environmental (rainfall) and pre-eruptive perturbations that are or not associated with edifice deformation. We will discuss the possible origins for such pre-eruptive perturbations (effects of magma pressure buildup or fluid pore pressure increase by heat transfer). In order to improve the depth resolution of our observations we deployed 3 seismic arrays for a total of 300 seismometers on PdF volcano in the framework of VolcArray project. We will present first results discussing how dense seismic arrays can be useful for noise-based seismic imaging and monitoring.