To date, seismic studies of Iceland have focused on either the mantle plume or crust variations and thickness. Region mantle tomography studies are able to resolve in the depth range ~450 to ~100 km where a cylindrical low velocity anomaly is observed. In the case of Iceland, techniques available for the study of shallow structure are limited to the thickness of the crust, to a depth of ~40 km. This leaves a gap in our resolution and understanding where the mantle interacts with the crust.

Our recently completed crustal study provides us with 3D S-velocity variations throughout the Icelandic crust, and a map of crustal thickness. The lateral variations are significant and could account for up to a 3 second variation in teleseismic S-phase delay times. This model, which is consistent with other recent crustal studies, allows an improved view of the mantle beneath including the region just below the crust.

Teleseismic arrivals recorded on the Passcal HOTSPOT and SIL networks are cross-correlated to obtain relative delay times. The spatial variation of these delays is observed to have two components, that of the known crustal variations superimposed on the mantle plume signature. We correct the teleseismic delays for crustal variations and invert for mantle structure. Preliminary results show a single, broad, low-velocity anomaly below 200 km, but above 200 km the anomaly becomes more complex in shape and can be seen to correlate with surface geological features. We expect to have our final model by the time of the meeting.