To date, uncertainties in tomographic images of the mantle beneath Iceland have been dominated by uncertainties in crustal velocity variations. The Icelandic crust is also of interest in its own right as it provides a laboratory for studying mid-ocean ridge processes. In an effort to improve our understanding of both crustal and mantle structure we present a 3-D crustal S-velocity model for Iceland.

We combine three types of data from two Icelandic networks. Most data comes from the HOTSPOT network, a recent two year PASSCAL deployment of 35 broadband stations. This data is complemented by the permanent SIL network operated by Vedurstofa Islands.

Love waves from strong earthquakes in Iceland form the basis of our model. Moment tensor solutions derived from both GSN and HOTSPOT surface waves are input to the Partitioned Waveform Inversion to obtain path-average velocity models. We also use Sn travel time picks to provide additional data on Moho depth and uppermost mantle velocity. Finally, we include point observations of Moho depth from previous studies, which were based primarily on Moho reflections. We combine all these data sets in a simultaneous linear inversion for the 3-D structure.

The waveform fits support the Moho variations implied by the point depth observations: Iceland's crust is thick beneath central Iceland above the center of the mantle plume and thinner beneath the neovolcanic zones to the north and southwest. Our preliminary models show low S-velocities in central Iceland, the location of the 1996 Vatnajokull Eruption, and along the neovolcanic zones. We expect to present our final 3-D model at the meeting.