The Azores archipelago is located near the triple junction between the Nubian (NU), North America (NA), and Eurasia (EU) plates. It is characterized by a relatively strong seismicity and active volcanism. The best estimate of the current plate velocities in the area over geologic timescales comes from the NUVEL1-NNR model (DeMets et al.) . At the geodetic timescale, plate motion models (Altamimi et al., Sella et al.) including GPS, DORIS, SLR and VLBI data currently do not yet include data from the Azores. In the framework of a research project focused on the seismotectonics and volcanotectonics of Sao Miguel island, we have analysed GPS data collected there in 1993, 1994, 1997, 2000 and 2002. Our analysis determines both the velocity in the REVEL (Sella et al.) reference frame of Sao Miguel and its internal deformation. The comparison of the 2000 and 2002 coordinates indicates that Sao Miguel accommodates moderate WNW-ESE extension at a rate slower than 5 mm yr(-1).
Univ Azores, Dept Geosci, CVARG, P-9501801 Ponta Delgada, Azores, Portugal; Inst Phys Globe, Equipe Sismol, F-75252 Paris 05, France; Inst Phys Globe, Equipe Geodesie, F-75252 Paris 05, France; Univ Iceland, Nordic Volcanol Inst, IS-108 Reykjavik, Iceland; CNRS, Toulouse, FranceArticleEnglish