Real time monitoring of vertical ground deformations during eruptions at Piton de la Fournaise

International audienceTilt changes related to a summit dike eraplacement at Piton de !a Fournaise volcano have been recorded by a 4 continuously recording electronic tiltmeters network during the April 18, 1990 eruption. The real-time processing of these data at the Observatory allows to calculate during the emplacement the relative position of the inflation center from the tilt vectors supplied by the nearby stations. Two main steps have been identified-an initial subvertical intrusion step, followed by a lateral dike migration from the summit cone. This monitoring allows to calculate a high average intrusion velocity of about 0.2 re. see-1 which can related to the highly fracturated pattern of the summit area