A new High-Resolution Model for the Velocity and Density Structure of Northwest Europe

A new high-resolution model for the crustal velocity structure of northwest Europe has been produced from wide-angle reflection seismic data. These data provide the best constraints on the P-wave velocity structure of the crust and depths to major interfaces (e.g.~Moho). Over 31000~km of wide-angle seismic profiles have been digitised to map the Moho depth and 3D variations in velocity structure. The profiles have been individually assessed and assigned uncertainties based primarily on the shot- and receiver-spacing, the data coverage and modelling method. Using 3D kriging, of the profiles, a regional model, with 40x40x1~km grid elements, has been produced. The velocity uncertainties assigned to the input data have been combined with the interpolation uncertainties to produce a quantitative estimation of the model uncertainty. Near surface sediment thicknesses were obtained from separate seismic reflection, borehole and geological databases since the resolution of near surface structure on most wide-angle seismic profiles is poor due to large shot and/or instrument spacing. Velocities were assigned to the sedimentary layer using a velocity-depth model constructed from normal incidence reflection data from around the UK. To the authors' knowledge the crustal model is unique in two respects: The high-resolution, resulting in greater detail in crustal structure, and the inclusion of quantitative uncertainties. The crustal velocity model has been converted to a density model using an empirical velocity-density function. This density model is currently being used to identify areas of buried loading and hence to investigate the isostatic balance of the crust and support for present day topography. Other possible uses of the model are: a starting model for tomography studies; improved earthquake location; and studies of crustal evolution.