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Mantle structure beneath the Macaronesian volcanic islands (Cape Verde, Canarie...
Civiero, Chiara; Carvalho, Joana; Silveira, GraçaOcean island volcanism provides a unique window into the nature of mantle composition, dynamics and evolution. The four Macaronesian archipelagos-Cape Verde, the Canaries, Madeira and the Azores-are the main magmatic systems of the Central-East Atlantic Ocean with volcanic activity that in some islands poses significant risk for the population. The recent development of regional seismic networks in these settin...
Crustal and uppermost mantle structure near the Gloria Fault, North Atlantic, f...
Pinzón, Juan I.; Custódio, Susana; Silveira, Graça; Krüger, Frank; Mata, João; Matias, LuisIn this work, we present both 1-D and 3-D shear wave velocity (Vs) models of the oceanic crust and uppermost mantle below the Deep OCean Test ARray area, located similar to 70 km north of the central section of the Gloria Fault, in the eastern North-Atlantic Ocean. The velocity models are inferred from the dispersion of surface waves recorded on ocean bottom seismometers. Dispersion measurements are obtained fr...
Heterogeneous seismic anisotropy beneath Madeira and Canary archipelagos reveal...
Schlaphorst, David; Silveira, Graça; Mata, João; Krüger, Frank; Dahm, Torsten; Ferreira, Ana M GMid-plate upward mantle flow is a key component of global mantle convection, but its patterns are poorly constrained. Seismic anisotropy is the most direct way to infer mantle flow as well as melt distribution, yet the convection patterns associated with plume-like mantle upwelling are understudied due to limited seismic data coverage. Here, we investigate seismic anisotropy beneath the Madeira and Canary hotsp...
Imaging the crust and uppermost mantle structure of Portugal (West Iberia) with...
Silveira, Graça; Dias, Nuno; Kiselev, Sergey; Stutzmann, Eleonore; Custodio, Susana; Schimmel, MartinWe present a new high-resolution three-dimensional (3D) shear wave velocity (Vs) model of the crust and uppermost mantle beneath Portugal, inferred from ambient seismic noise tomography. We use broadband seismic data from a dense temporary deployment covering the entire Portuguese mainland between 2010 and 2012 in the scope of the WILAS project. Vertical component data are processed using phase correlation and ...
Sparsity-promoting approach to polarization analysis of seismic signals in the ...
Mohammadigheymasi, Hamzeh; Crocker, Paul; Fathi, Maryam; Almeida, Eduardo; Silveira, Graça; Gholami, Ali; Schimmel, MartinTime - frequency (TF)-domain polarization analysis (PA) methods are widely used as a processing tool to decompose multicomponent seismic signals. However, as a drawback, they are unable to obtain sufficient resolution to discriminate between overlapping seismic phases, as they generally rely on a low-resolution time-frequency representation (TFR) method. In this article, we present a new approach to the TF-doma...
Crustal and uppermost mantle structure of Cape Verde from ambient noise tomography
Carvalho, J.; Silveira, Graça; Kiselev, S; Custódio, Susana; Dos Santos Ramalho, Ricardo; Stutzmann, E; Schimmel, MWe present a seismic ambient noise tomography of the Cape Verde archipelago, located in the Atlantic Ocean, approximately 600 km west of Senegal. We used 38 seismic broad-band stations that continuously recorded for 10 months, in order to construct the first 3-D model of Sv-wave velocities for the crust and uppermost mantle beneath the Cape Verde region. We started by computing phase cross-correlations for vert...
Imaging the crust and uppermost mantle structure of Portugal (West Iberia) with...
Silveira, Graça; Dias, Nuno Afonso; Kiselev, Sergey; Stutzmann, Eleonore; Custódio, Susana; Schimmel, MartinWe present a new high-resolution 3-D shear wave velocity (Vs) model of the crust and uppermost mantle beneath Portugal, inferred from ambient seismic noise tomography. We use broad-band seismic data from a dense temporary deployment covering the entire Portuguese mainland between 2010 and 2012 in the scope of the WILAS project. Vertical component data are processed using phase correlation and phase weighted sta...
3D-ambient noise surface wave tomography of Fogo volcano, Cape Verde
Carvalho, J.; Silveira, Graça; Dumont, Stéphanie; Ramalho, Ricardo Dos SantosFogo volcano belongs to the Cape Verde Archipelago, and it is one of the most active volcanoes in the Atlantic Ocean, which most recent eruption occurred from November 2014 to February 2015. We analyzed ambient seismic noise recordings of three different networks deployed in the island, totalizing 14 seismic stations, to derive a crustal 3D shear-wave crustal velocity model of the volcano. Through the phase cro...
PRISM3D: a 3-D reference seismic model for Iberia and adjacent areas
Arroucau, Pierre; Custódio, S.; Civiero, Chiara; Silveira, Graça; Dias, Nuno; Diaz, J.; Villasenor, A.; Bodin, ThomasWe present PRISM3D, a 3-D reference seismic model of P- and S-wave velocities for Iberia and adjacent areas. PRISM3D results from the combination of the most up-to-date earth models available for the region. It extends horizontally from 15 degrees W to 5 degrees E in longitude, 34 degrees N to 46 degrees N in latitude and vertically from 3.5 km above to 200 km below sea level, and is modelled on a regular grid ...
Response of Fogo volcano (Cape Verde) to lunisolar gravitational forces during ...
Dumont, Stéphanie; Silveira, Graça; Custódio, Susana; Lopes, Fernando; Le Mouel, Jean-Louis; Gouhier, Mathieu; GUEHENNEUX, YannickVolcanoes are complex systems that evolve in space and time as a result of their eruptive activity. Volcanic eruptions represent the ultimate expression of a complex interplay between internal and external processes that span across different time scales. Deciphering how internal and external processes interact at the time scale of eruptions may provide key insights on the temporal evolution of eruptions and al...