Investigating variations in upper crustal layering and lower crustal magmatism beneath the Faroe Islands using passive seismic data (Faroe Islands Passive Seismic Experiment)

Abstract

We conducted a passive seismological experiment that was designed to constrain variations in crustal structure beneath the Faroe Islands (Faroe Islands Passive Seismic Experiment). After collecting approximately 15 months’ of continuous (100Hz) data using Güralp CMG‐3ESPD seismometers at 12 sites that span the Faroe Islands landmass, we applied the receiver function method to global teleseismic earthquakes that were recorded by the FIPSE array in order to examine P‐S‐wave conversions that arise from major acoustic impedance discontinuities in the subsurface. The data quality recorded by the FIPSE array is relatively poor, due to the microseismic noise from waves and wind, and data recovery was 86% across the entire FIPSE network. Receiver functions calculated from teleseismic earthquakes have been analysed and preliminary results show that a crustal thickness of 29±4km and average crustal VP/VS of 1.76±0.09 occurs beneath the Faroe Islands crust. The properties of the crust and the character of the Moho appear to vary from north to south, with Suduroy and Sandoy exhibiting a different upper crustal structure than the remainder of the Faroe Islands. We also find evidence for a gradational, high‐velocity lower crustal layer with VP/VS>1.80.