Scientific topics

Hydrothermal systems are found at most active volcanoes and their understanding is important for following reasons : Variations in hydrothermal circulation reflect the temporal evolution of the volcanic activity like the reactivation of the magmatic processes or preparation of the volcanic crisis ; Hydrothermal systems may interact with magma ascent leading to explosive hydro-magmatic eruptions ; Their emplacement and geometry are controlled by principal geological structures, therefore (...)

***WHAT IS PHYSICAL VOLCANOLOGY ?
The surprising diversity of magmas erupted at the Earth’s surface is caused by the chemical evolution taking place because magmas are cooling within the Earth’s crust and crystallize, encounter new magmas and mix, and interact with the wall rock. Our broadest scientific objective is to unravel, from a physical standpoint, the complex interplays between crystals, exsolution bubbles, and melt that affect the pressure/temperature path of magmas and condition (...)

Numerical modeling is used to characterize : the stability of volcanic edifices and magma storage zones (condition for caldera formation) ; the edifice rheology, the role of the edifice in the crust/edifice and magma/edifice interaction ; the stress field during magma transfer ; the consequences of a given external perturbation (edifice collapse, surface unloading due to glacier retreat…) on a magma storage zone (resulting deformation, seismicity, evolution of the stability) ; the (...)

The knowledge of the distribution of masses (densities) and elastic modules in a volcanic edifice is needed to understand its mechanical behaviour and to perform the modelling of its deformation. In this frame we set up an earthquake arrival-time tomographic inversion method, using an accurate numerical scheme for the computation of theoretical travel times and a bayesian regularization of the inverse problem. This method allows us to get a stable and accurate spatial distribution of the (...)

InSAR (Interferometry of Synthetic Aperture Radar data) is used to obtain maps of surface displacements in volcanic areas. Displacements are induced by magma transport and storage at shallow depth, loading due to eruptive deposits emplacement or volcanoes instabilities. They are used to image magmatic storage zones.
Figure 1 : Deformation at Colima Volcano (Mexico) from 2002 to 2006 obtained by ENVISAT data. Mean velocity in LOS in mm/year for the summit area of Colima Volcano (positive (...)

Seismic activity is one of the main precursors of volcanic eruptions. This activity, which is low during volcanic quiescence, can strongly increase in the months, weeks or days preceding eruptions. The study of volcanic seismicity is the basis of monitoring methods and eruption forecasting. Furthermore, the analysis of the various types of earthquake which occur inside volcanoes allow understanding better physical processes in magmatic and hydrothermal systems.
We develop specific methods (...)