TY  - JOUR
A1  - Vales, Dina
A1  - Dias, Nuno A.
A1  - Rio, Ines
A1  - Matias, Luis
A1  - Silveira, Graca
A1  - Madeira, Jose
A1  - Weber, Michael H.
A1  - Carrilho, Fernando
A1  - Haberland, Christian
T1  - Intraplate seismicity across the Cape Verde swell: A contribution from a temporary seismic network
JF  - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth
N2  - We present an analysis and characterization of the regional seismicity recorded by a temporary broadband seismic network deployed in the Cape Verde archipelago between November 2007 and September 2008.
 The detection of earthquakes was based on spectrograms, allowing the discrimination from low-frequency volcanic signals, resulting in 358 events of which 265 were located, the magnitudes usually being smaller than 3. For the location, a new 1-D P-velocity model was derived for the region showing a crust consistent with an oceanic crustal structure. The seismicity is located mostly offshore the westernmost and geologically youngest areas of the archipelago, near the islands of Santo Antao and Sao Vicente in the NW and Brava and Fogo in the SW. The SW cluster has a lower occurrence rate and corresponds to seismicity concentrated mainly along an alignment between Brava and the Cadamosto seamount presenting normal faulting mechanisms. The existence of the NW cluster, located offshore SW of Santo Antao, was so far unknown and concentrates around a recently recognized submarine cone field; this cluster presents focal depths extending from the crust to the upper mantle and suggests volcanic unrest No evident temporal behaviour could be perceived, although the events tend to occur in bursts of activity lasting a few days. In this recording period, no significant activity was detected at Fogo volcano, the most active volcanic edifice in Cape Verde.
 The seismicity characteristics point mainly to a volcanic origin. The correlation of the recorded seismicity with active volcanic structures agrees with the tendency for a westward migration of volcanic activity in the archipelago as indicated by the geologic record. (C) 2014 Elsevier B.V. All rights reserved.
KW  - Intraplate seismicity
KW  - Clustering
KW  - Local magnitude scale
KW  - Active volcanism
KW  - Cape Verde
KW  - Atlantic Ocean
Y1  - 2014
U6  - https://doi.org/10.1016/j.tecto.2014.09.014
SN  - 0040-1951
SN  - 1879-3266
VL  - 636
SP  - 325
EP  - 337
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Czuba, Wojciech
A1  - Grad, Marek
A1  - Mjelde, Rolf
A1  - Guterch, Aleksander
A1  - Libak, Audun
A1  - Krüger, Frank
A1  - Murai, Yoshio
A1  - Schweitzer, Johannes
T1  - Continent-ocean-transition across a trans-tensional margin segment: off Bear Island, Barents Sea
JF  - Geophysical journal international
N2  - P>A 410 km long Ocean Bottom Seismometer profile spanning from the Bear Island, Barents Sea to oceanic crust formed along the Mohns Ridge has been modelled by use of ray-tracing with regard to observed P-waves. The northeastern part of the model represents typical continental crust, thinned from ca. 30 km thickness beneath the Bear Island to ca. 13 km within the Continent-Ocean-Transition. Between the Hornsund FZ and the Kn circle divide legga Fault, a 3-4 km thick sedimentary basin, dominantly of Permian/Carboniferous age, is modelled beneath the ca. 1.5 km thick layer of volcanics (Vestbakken Volcanic Province). The P-wave velocity in the 3-4 km thick lowermost continental crust is significantly higher than normal (ca. 7.5 km s-1). We interpret this layer as a mixture of mafic intrusions and continental crystalline blocks, dominantly related to the Paleocene-Early Eocene rifting event. The crystalline portion of the crust within the south-western part of the COT consists of a ca. 30 km wide and ca. 6 km thick high-velocity (7.3 km s-1) body. We interpret the body as a ridge of serpentinized peridotites. The magmatic portion of the ocean crust accreted along the Knipovich Ridge from continental break-up at ca. 35 Ma until ca. 20 Ma is 3-5 km thicker than normal. We interpret the increased magmatism as a passive response to the bending of this southernmost part of the Knipovich Ridge. The thickness of the magmatic portion of the crust formed along the Mohns Ridge at ca. 20 Ma decreases to ca. 3 km, which is normal for ultra slow spreading ridges.
KW  - Controlled source seismology
KW  - Dynamics of lithosphere and mantle
KW  - Crustal structure
KW  - Atlantic Ocean
Y1  - 2011
U6  - https://doi.org/10.1111/j.1365-246X.2010.04873.x
SN  - 0956-540X
VL  - 184
IS  - 2
SP  - 541
EP  - 554
PB  - Oxford Univ. Press
CY  - Oxford
ER  -