UHR 3D Seismic Study of Ice-Related Deformation Structures Offshore NL

2D, and particularly 3D Ultra High Resolution (UHR) seismic surveying has become an invaluable tool for assessing the geological subsurface for offshore wind developments. In the case of The Ten noorden van de Waddeneilanden Wind Farm Zone (TNWWFZ), a number of geohazards have been detected using these techniques including tunnel valleys, deformed sediments, shallow gas, etc. These features are variable in size and type of sediment infill, with some exhibiting deformation characteristic of glacial tectonic activity and others of buried dead ice landscapes. Both the deformation and complexity of sedimentation raises concerns for engineers as it puts into question the load bearing capacity of the subsurface. Glacial tectonics form during fully glacial conditions whilst kettle holes form during glacial regression when sediments bury dead ice within the landscape. Once buried this dead ice is subjected to higher pressure and temperature causing it to melt forming a small valley and depositing any previously frozen sediment. The resulting depressions can accommodate large volumes of sediments and create a 3D distribution of properties that is impossible to model without 3D seismic data or very dense 2D grids.