%0 Journal Article
%@ 0016-7746
%A van Dalfsen, W.
%A Doornenbal, J. C.
%A Dortland, S.
%A Gunnink, J. L.
%A TNO Built Environment and Geosciences - Geological Survey of the Netherlands, the Netherlands.,
%A TNO Built Environment and Geosciences - Geological Survey of the Netherlands, the Netherlands.,
%A TNO Built Environment and Geosciences - Geological Survey of the Netherlands, the Netherlands.,
%A TNO Built Environment and Geosciences - Geological Survey of the Netherlands, the Netherlands.,
%D 2006
%F epos:1768
%I Cambridge University Press
%J Netherlands Journal of Geosciences
%K Netherlands; geostatistics; interval velocities; lithostratigraphic layers; seismic velocities; sonic logs
%N 04
%P 277-292
%T A comprehensive seismic velocity model for the Netherlands based on lithostratigraphic layers
%U https://episodesplatform.eu/eprints/1768/
%V 85
%X A seismic velocity model is necessary to map depth and thickness of subsurface layers interpreted from seismic reflection images. We have built a seismic velocity model (VELMOD-1) for the entire Netherlands area, both onshore and offshore, using non-confidential data (sonic logs, time-depth pairs, lithostratigraphic marker depths and downhole position data) of 720 boreholes in DINO - National Geoscientific Portal, and a preliminary isochore map (in seismic traveltime representation) of the layer of the Zechstein Group. The model is based on the Vint-zmid method applied to the following lithostratigraphic layers: Lower, Middle and Upper North Sea groups; Chalk Group; Rijnland Group; Schieland, Scruff and Niedersachsen groups; Altena Group; Lower and Upper Germanic Trias groups; Upper Rotliegend Group; and Limburg Group. Per layer, the linear least squares approximation, applied to Vint as a function of zmid, provides parameters V0 and K for a linear velocity function V(z) = V0 + K · z. In VELMOD-1, K is constant, at least at the scale of structural elements, whereas V0 varies with location. At borehole locations, V0 is calibrated such that traveltime through the layer according to the linear velocity model equals the traveltime according to the borehole data. A kriging procedure is applied to the calibrated V0(x, y)-values resulting in an estimated V0-value at any other location. The model V0-values were determined on an areal grid with cells of 1 km × 1 km. On the same grid, kriged interval velocities constitute the model for the Zechstein Group. These interval velocities stem directly from interval velocities at borehole locations; at other positions they are also dependent on the thickness (in terms of seismic traveltime isochores) of the layer of the Zechstein Group. Maps are presented of the distributions of both V0 and its standard deviation for two layers: that of the Chalk Group and that of the Lower and Upper Germanic Trias groups.