Surface displacement field at Terceira island deduced from repeated GPS measurements
Miranda JM, Navarro A, Catalão J, Fernandes RMS
JVGR, Volumes 217–218, 1 March 2012, Pages 1–7. doi:10.1016/j.jvolgeores.2011.10.009
We present the results of six GPS (Global Positioning System) campaigns held in Terceira Island (Azores) between 1999 and 2006 for a group of 17 stations, to estimate the surface displacement field induced by the Eurasian–Nubian interplate motion, and their relationship with the rifting along Terceira Rift and volcanic processes at the island scale. We show that the whole island mainly behaves like a rigid body which absolute motion is closer to Eurasia. The magnitude of the computed intra-island horizontal deformation field (difference between the individual site velocities and the mean rigid-body motion) is still below the observation accuracy, and so cannot be directly related with local processes. We also show that the island is globally subsiding with an average rate close to 1 mm/yr, as it moves to the NE away from the Terceira Rift, mostly attached to the Eurasian plate. The high subsidence rate can be the result of the volcanic processes that shaped the Serreta ridge, NW of Terceira.