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Estimation of the Terceira Island (Azores) main strain rates from GPS data

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Abstract

The nature and location of the present EUR/AFR boundary configuration in the Azores region is controversial and, in particular, the pattern of the present day deformation associated with plate boundary processes, is still unknown. We present here GPS data from 10 stations, in a segment of this boundary (Terceira Island), where data at 2 epochs (1999 and 2001) are available. GPS data were processed using GAMIT and FONDA, with horizontal position repeatability circa 3 mm and 2 mm, respectively, for 1999 and 2001 epochs. Stations horizontal displacements range from 0.96 to 4.60 mm/yr. Strain analysis indicates compression for four sub-networks. The rates of local rotation are consistent for three sub-networks on the western part of Terceira, exhibiting a clockwise rotation of about 8° per million years. Although they are still preliminary, these results are discussed in relation with the expected behaviour from regional geodynamic constraints and past geodetic studies.

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Correspondence to Ana Navarro.

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Navarro, A., Catalão, J., Miranda, J.M. et al. Estimation of the Terceira Island (Azores) main strain rates from GPS data. Earth Planet Sp 55, 637–642 (2003) doi:10.1186/BF03352470

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Key words

  • Azores triple junction
  • crustal deformation
  • GPS
  • Terceira Island