Crustal structure beneath the Faroe Islands from teleseismic receiver functions

We use teleseismic receiver function analysis to constrain the crustal structure beneath the Faroe Islands on the northwest European volcanic continental margin. A cluster of 45 broad-band seismometers on the Glyvursnes peninsula, Streymoy Island recorded 10 teleseismic events ranging in magnitude from 6.1 to −8.0 during July–December 2003. Receiver functions show a clear Ps peak for the first time in this region. The depth of the converting boundary is estimated as 29–32 km using forward and inverse modelling and thickness versus VP/VS ratio stacking techniques. Modelling experiments suggest that this estimate may represent the conversion from a region of high-velocity lower crust rather than the crust–mantle transition at the Moho. The best-fit modelling results were achieved with a gradational high-velocity region at least 6 km thick in the lower crust. This is interpreted as due to the emplacement of sills into pre-existing continental crust rather than the simple underplating of a block of high velocity igneous material at its base.