The continental margin in Iceland — A snapshot derived from combined GPS networks

The tectonical setting in Iceland is quite complex due to the interaction of the Iceland hot spot and the Mid Atlantic Ridge. While in the north of the island one active spreading zone exists, the divergent motion in the centre and the south is distributed over at least two volcanic rift zones. The spreading rate increases linearly along the Western Volcanic Zone from north to south up to 8 mm/yr at the Hengill triple junction. On the contrary, the spreading rate of the parallel Eastern Volcanic Zone decreases from 16 mm/yr down to 6 mm/yr at the island's southern coast. The Hreppar microplate between the two predominant rift zones has an independent motion, which is distinct from that of the Eurasian and North American plates. A new detected feature is the spreading activity around the Hofsjökull volcanic zone located in the centre of Iceland with a significant rate of 6 mm/yr. During this investigation the coordinate sets of nearly 20 years of GPS data acquisition on Iceland were combined to get a velocity field for the surface of Iceland. This velocity field is based on a linear kinematic model with the consideration of local non-linear effects like volcano up-doming and displacements due to major earthquakes.