Crustal Deformation Studies of the Iberian Peninsula

Séminaire le 14 déc 2018 à10h30

Intervenant : Giorgi KHAZARADZE

Professeur agrégé Department of Earth and Ocean Dynamics

Salle Coriolis Observatoire Midi-Pyrénées – 14, avenue Edouard Belin – 31400 Toulouse

Voir le plan d’accès

I will present a preliminary 3D crustal deformation velocity field of the Iberian Peninsula based on the analysis of more than 400 continuous GPS station data from the last 8 years (2010 to 2018) distributed throughout the Iberian Peninsula, northern Africa and southern France. We describe the procedures followed to obtain a combined uniform velocity solution from daily GPS data using GAMIT/GLOBK software of MIT.

The previous studies have estimated only the 2D horizontal rates, since the vertical component of deformation is more complicated to derive. Only the studies by Serpelloni et al. (2013) and Nguyen et al. (2016) have calculated the vertical rates of deformation in some limited areas of the Iberian peninsula. In the present work, we provide the main results in terms of the velocity vectors in horizontal and up/down directions. The calculated horizontal GPS indicate that the Iberian Peninsula presents a heterogeneous present-day crustal deformation field, which can be grouped into 7 distinct domains/blocks. Each domain is influenced by the geo-tectonic structural configuration of the Iberian Peninsula and by the proximity to the Iberia-Nubia plate boundary. The highest velocities, as well as the highest geodetic strain rates, are detected in the Eastern Betics Shear Zone (EBSZ) and along the Iberia-Nubia plate boundary, areas with the highest seismicity rates. The obtained vertical GPS velocities are preliminary and perhaps, in the future, a more careful treatment of various phenomena affecting the GPS vertical signal (e.g. ocean and tide loading) should be performed in order to better resolve them. However, we do detect points, where the observed vertical rates exceed 10 mm/yr. These motions, although real, obviously cannot be related to the tectonics. For example a subsidence of 6 cm/yr in Guadalentín basin near the city of Lorca is caused by the groundwater extraction. This kind of information is useful for multi-risk analysis since it can provide information of ongoing uplift/subsidence motion, that can be caused by faults, landslides, sediment settlement and/or anthropogenic activities (e.g. groundwater withdrawal, mining).

Plus d'actualités

Actualité

C’est la faille qui casse l’oeuf ou l’oeuf qui casse la faille ? de failles et volcans au sud Chili

Le sud de la marge Andine comporte de nombreux systèmes volcaniques, géothermaux et minéralisés, témoins d’une migration importante de fluides à travers la croûte. On ne comprend pas bien comment […]

29.07.2021

Actualité

Comment les falaises basques s’effondrent-elles ?

La Corniche Basque, entre Saint-Jean de Luz et Hendaye est fragilisée par la mer, ce qui met en péril le sentier littoral et une route départementale. Une équipe de recherche […]

22.07.2021

Actualité

La formation du plateau de Démérara

La marge continentale du Craton des Guyanes s’est formée à l’intersection entre l’Océan Atlantique et Équatorial, formés successivement depuis 150 Ma, achevant ainsi la dispersion du supercontinent Gondwana. Au cours […]

Rechercher