Investigating the relationship between the presence of active seismicity and the displacement of the eastern flank of Piton de la Fournaise, La Réunion.

Geodetic observations indicate a seaward displacement of the eastern flank of Piton de la Fournaise volcano on La Réunion Island. Previous studies have suggested that the this displacement could be the result of a sheared sill. However, the location of the sill inferred from InSAR data is currently inconsistent with the distribution of earthquakes observed at greater depth. However, other results have attributed the current distribution of seismic activity beneath the eastern flank to the combined effect of overpressure in the magma chamber and loading of the volcanic edifice. The aim of the our study is to investigate the relationship between these two phenomena: the presence of active seismicity and the displacement of the eastern flank of Piton de la Fournaise. With this purpose, we enhance the characterization of seismic activity using template matching, double-difference relocation and focal mechanisms determination. We then explore the link between the spatio-temporal evolution of the seismicity and the displacement of the eastern flank. Additionally, we evaluate the impact of the velocity model to determine if we can reconcile hypocenter locations with the destabilization structure inferred from InSAR.