Modelización de las deformaciones asociadas a procesos intrusivos en áreas volcánicas y su aplicación a la isla de El Hierro (Islas Canarias)

Resum

The 2011-2014 volcanic activity at El Hierro (Canary Islands) was characterized by the occurrence a submarine eruption and the emplacement of multiple magmatic intrusions at depth.In mid-July 2011, an intense seismic swarm was detected beneath the center of the island that propagated laterally ~15 km from north to south until culminating, three months later, in a submarine eruption less than 2 km off its southern coast. The eruption lasted 4 months and produced large gas bubbles, lava balloons and extensive areas of ash and lapilli on the sea surface, as well as a volcanic cone on the seafloor called Tagoro. The end of the eruptive activity did not mark the end of the volcanic activity on El Hierro. Between four months and two years later, six intrusive episodes were detected beneath the island. Each of these episodes lasted between 3 and 20 days and produced significant ground deformations and intense seismic swarms, confirming the transport and accumulation of magma at depth. However, none of the post-eruptive intrusions culminated in a new eruption.The objective of this thesis is to study from a geodetic point of view the spatial and temporal evolution of the six post-eruptive intrusive episodes on El Hierro using Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) observations. Surface displacements have been obtained using data from ten continuous GNSS stations and 44 Synthetic Aperture Radar images captured by the Canadian RADARSAT-2 satellite and the Italian COSMO-SkyMed satellite constellation. These observations have made it possible to quantify and characterize the surface displacements of the island during each intrusive episode. The inversion of the geodetic data, using a Bayesian approach and analytical models of deformation sources, has allowed estimating the main characteristics of the intrusions responsible for such ground deformations, such as their location, geometry, volume increase or magma flow at depth, as well as their evolution in time and space...