HR: 1340h
AN: G53B-0880    [Abstracts]
TI: Two Years of InSAR Monitoring of Volcanic Activity at Piton de la Fournaise (Reunion Island) Using ASAR-ENVISAT Data
AU: Tinard, P
EM: p.tinard@opgc.univ-bpclermont.fr
AF: Laboratoire Magmas et Volcans, Université Blaise Pascal - UMR 6524, 5, rue Kessler, Clermont-Ferrand, 63038 France
AU: Froger, J
EM: froger@opgc.univ-bpclermont.fr
AF: IRD, IR 163 / Laboratoire Magmas et Volcans, Departamento de Geologia, Universidad de Chile, Plaza Ercilla 803, Santiago, 1 Chile
AU: Briole, P
EM: briole@ipgp.jussieu.fr
AF: CNRS-UMR 7580, Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75005 France
AU: Staudacher, T
EM: Thomas.Staudacher@univ-reunion.fr
AF: Observatoire Volcanologique du Piton de la Fournaise, IPGP, 14 RN3, le 27ème, La Plaine des Cafres, 97418 France
AU: Cayol, V
EM: Cayol@opgc.univ-bpclermont.fr
AF: Laboratoire Magmas et Volcans, Université Blaise Pascal - UMR 6524, 5, rue Kessler, Clermont-Ferrand, 63038 France
AU: * Fukushima, Y
EM: Yofukushima@opgc.univ-bpclermont.fr
AF: Laboratoire Magmas et Volcans, Université Blaise Pascal - UMR 6524, 5, rue Kessler, Clermont-Ferrand, 63038 France
AU: Souriot, T
EM: Souriot@opgc.univ-bpclermont.fr
AF: Laboratoire Magmas et Volcans, Université Blaise Pascal - UMR 6524, 5, rue Kessler, Clermont-Ferrand, 63038 France
AB: After an unusually long period of 65 months of rest, Piton de la Fournaise volcano (R'eunion Island) started erupting on March 1998. This event marks the beginning of a new cycle of activity which still continues today. In the last two years, Piton de la Fournaise had 8 eruptions (April 2003 to May 2005). This period also coincides with the beginning of systematic data acquisition by the ASAR radar on board of the ENVISAT satellite. With respect to ERS satellites, ENVISAT allows to acquire images in seven different swaths which significantly improves the monitoring capability of InSAR. It increases the revisit time from 35 days to 2.5 days and enhances the data quality for interferometric purpose. In order to monitor the volcanic activity, we use 117 ASAR images acquired between February 2003 and May 2005. We produce a dataset of more than 500 interferograms which provides a unique record of the ground displacements associated with each individual eruption. The February 2005 eruption gave the opportunity to compute three interferograms just a couple of hour after the satellite passed over the erupting volcano, leading to near real time InSAR monitoring of volcanic activity. Accurate maps of the ground displacements and lava flows were computed and provided to the Volcano Observatory of Piton de la Fournaise in less than a half-day, thanks both to ESA facilities and to our optimized interferometric processing chain. For most of the past two years eruptions, the observed ground displacements are compatible with the opening of eastward-dipping dykes in the N10°E and S10°E volcano rift zones. Using a 3D mixed boundary element method for elastic media coupled with a neighbourhood algorithm, we determined the characteristics of the dykes formed. The best-fit models converge towards a set of dyke dipping 45° to 55° eastward whose bottoms lie at around 1,500 m asl (depth 800 - 1,000 m). The repetition of dyke intrusions may have weakened the volcanos flank and then promoted the large displacements of the January 2004 event.
DE: 1243 Space geodetic surveys
DE: 6914 Electromagnetic noise and interference
DE: 8419 Volcano monitoring (7280)
DE: 8485 Remote sensing of volcanoes
DE: 9340 Indian Ocean
SC: Geodesy [G]
MN: Fall Meeting 2005