Accueil > Recherche > Équipes > Géophysique des volcans > Thèses > Thèses soutenues > Compréhension des processus magmatiques et localisation des sources sismo-volcaniques avec des antennes sismiques multicomposantes - Adolfo INZA
12 juin 2013 ( dernière mise à jour : 19 septembre 2016 )
Sujet de thèse : Compréhension des processus magmatiques et localisation des sources sismo-volcaniques avec des antennes sismiques multicomposantes.
Encadrants : Jérôme Mars, Jean-Philippe Métaxian, Christopher Bean.
Soutenue le 30 mai 2013.
In this thesis, we study the seismo-volcanic source localization using data recorded by new sensor arrays composed of three-component (3C) seismometers deployed on Ubinas stratovolcano (Peru). We develop a new framework (MUSIC-3C) of source localization method based on the well-known MUSIC algorithm. To investigate the performance of the MUSIC-3C method, we use synthetic datasets designed from eight broadband isotropic seismic sources located beneath the crater floor at different depths. The fundamental scheme of the MUSIC-3C method exploits the fact of the cross-spectral matrix of 3C array data, corresponding to the first seismic signal arrivals, provides of useful vector components (slowness, back-azimuth and incidence angle) from the seismic source. Application of the MUSIC-3C method on synthetic datasets shows the recovery of source positions. Real data used in this study was collected during seismic measurements with two seismic antennas deployed at Ubinas volcano in 2009, whose experiment conduced by volcanic teams of IRD-France (l’Institute de Recherche pour le D\’eveleppment), Geophysics group University College Dublin Ireland and Geophysical Institute of Peru (IGP). We apply the MUSIC-3C algorithm to investigate wave fields associated with the magmatic activity of Ubinas volcano. These analysis evidence a complex mechanism of vulcanian eruptions in which their seismic sources are found at two separated sources located at depths of 300 m and 1100 m beneath the crater floor. This implies the reproduction of similar mechanisms into the conduit. Based on the eruptive mechanisms proposed for other volcanoes of the same type, we interpret the position of this sources as the limits of the conduit portion that was involved in the fragmentation process.
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