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During the TopoIberia experiment, a total of 26 seismic broadband stations were recording in northern Morocco, providing for the first time extended regional coverage for investigating structure and seismotectonics of the southern branch of the Betic-Rif arc, its foreland, and the Atlas domain. Here, we analyze P-to-S converted waves in teleseismic receiver functions to infer gross crustal properties as thickness and Vp/Vs ratio. Strong lateral variations of the crustal thickness are observed throughout the region. Crustal thicknesses vary between 22 and 44 km and display a simple geographic pattern that divides the study area into three domains: entire northwestern Morocco underlain by a thickened crust with crustal thicknesses between 35 and 44 km; northeastern Morocco affected by significant crustal thinning, with crustal thicknesses ranging from 22 to 30 km, with the shallowest Moho along the Mediterranean coast; and an extended domain of 27–34 km thick crust, farther south which includes the Atlas domain and its foreland regions. Vp/Vs ratios show normal values of 1.75 for most stations except for the Atlas domain, where several stations give low Vp/Vs ratios of around 1.71. The very sharp transition from thick crust in northwestern Morocco to thin crust in northeastern Morocco is attributed to regional geodynamics, possibly the realm of present-day subcrustal dynamics in the final stage of western Mediterranean subduction. Crustal thicknesses just slightly above 30 km in the southern domain are intriguing, showing that high topography in this region is not isostatically compensated at crustal level., Instituto Andaluz de Geofísica, Universidad de Granada, España, Departamento de Física Teórica y del Cosmos, Universidad de Granada, España, Departamento de Geofisica, Universidade Federal do Rio Grande do Norte, Brasil, Programa de Pós-graduacão em Geodinâmica e Geofísica, Universidade Federal do Rio Grande do Norte, Brasil, Instituto de Ciencias de la Tierra Jaume Almera, España, Real Observatorio de La Armada, España, Departamento de Geofísica, Universidad Complutense de Madrid, España, Departamento de Geología, Universidad de Oviedo, España, Instituto Geológico y Minero de España, España, Institut Scientifique, Université Mohammed V, Marruecos, Departamento de Geodinámica, Universidad de Granada, España

The present project is a joint effort between different institutions to deploy a dense seismic network at Gran Canaria island (Canary Islands, Spain). The interstation distance is around 20 km. The broadband seismic network is composed of one permanent (Guralp CMG-3T 120 s) and five temporary stations (Guralp CMG-3ESP 60 s). The permanent station is a 120 s Guralp CMG-3T and belongs to the Canary Island Seismic Network, run by the Instituto Geográfico Nacional (IGN) of Spain. The temporary stations are 60 s Guralp CMG-3ESP, provided by the GFZ seismic pool. The deployment was carried out in December 2009. The stations will be recording during two years. The improvement of the seismic network allow us to tackle the following issues: the detection and analysis of any local seismicity of tectonic and/or volcanic origin at Gran Canaria island; to contribute to the understanding of the regional seismicity with special interest in the oceanic channel between Tenerife and Gran Canaria Island in collaboration with a project running a dense temporary seismic network in Tenerife; to study the crustal and upper mantle structure, under Gran Canaria to constrain the crustal structure, the source of the volcanism, and better sample the mantle discontinuities and anisotropy. To study the Earth structure, we use receiver function analysis, ambient seismic noise and SKS anisotropy techniques, This project is part of a long-term research of the crustal and the mantle structure of the Canary Islands, which has started with Gran Canaria and Tenerife Islands and will eventually continue with the rest of the archipelago. The origin of the Canary Islands is generally attributed to a broad mantle upwelling under a slow moving plate, resulting in spatially and temporally distributed volcanic activity and a large number of seamounts and islands. A controversial discussion has been going on about the factors that control the evolution of the volcanic edifices, the type of the melting anomaly (a single, well defined mantle plume of a larger area of diffuse mantle upwelling), and the tectonic control of this evolution. This study is foreseen to provide important clues to understand the volcanic structure and tectonic evolution of the Gran Canaria Island.