HR: 14:55h
AN: V23C-06    [Abstracts]
TI: Complex Dike Intrusions at Piton de la Fournaise Revealed by Numerical Modeling of InSAR Data
AU: * Fukushima, Y
EM: yofukushima@opgc.univ-bpclermont.fr
AF: Laboratoire Magmas et Volcans, Univ. B. Pascal, CNRS UMR 6524, 5 rue Kessler, Clermont-Ferrand, 63038 France
AU: Durand, P
EM: philippe.durand@cnes.fr
AF: Centre National d'Etudes Spatiales, 18 Avenue E. Belin, Toulouse, 31055 France
AU: Cayol, V
EM: valerie.cayol@opgc.univ-bpclermont.fr
AF: Laboratoire Magmas et Volcans, Univ. B. Pascal, CNRS UMR 6524, 5 rue Kessler, Clermont-Ferrand, 63038 France
AU: Massonnet, D
EM: didier.massonnet@cnes.fr
AF: Centre National d'Etudes Spatiales, 18 Avenue E. Belin, Toulouse, 31055 France
AB: In 1998, Piton de la Fournaise (Réunion Island) entered into a new eruptive cycle after five years of quiescence. Interferograms associated with the first five eruptions of this cycle were computed from the RADARSAT-1 images. The interferograms indicate complex displacement fields, which call for numerical modeling methods to allow more complex and realistic modeling than the usually used analytical models. A three dimensional mixed boundary element method is combined with a neighbourhood algorithm inversion to search for dike models that best explain the observed interferograms. Each eruption requires a specific parameterization of the dike model(s); in some cases, a curved dike surface must be introduced to better explain data, and in other cases, simultaneous inversions for two dikes are required because of their proximity. Most of the estimated dikes dip seaward with a typical angle of 65 degrees. The dike associated with the first eruption of the cycle (March 1998) is estimated to originate from sea level (2600 m below the summit), whereas those associated with the following eruptions are estimated to be mostly shallower than 1000 m below the ground. A stress change analysis indicates that the location of a dike is influenced by the previously emplaced dikes.
DE: 8000 STRUCTURAL GEOLOGY
DE: 8145 Physics of magma and magma bodies
DE: 8400 VOLCANOLOGY
DE: 8434 Magma migration and fragmentation
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005