Energy Island

SolidGround quantified geotechnical parameters from seismic data to support foundation de-risking of the Danish Energy Island — a planned offshore hub in the North Sea that will play a central role in expanding Northern European offshore wind capacity. The work was delivered for Energinet, alongside leading experts from the offshore wind industry.

The construction of an artificial island requires a clear understanding of how the subsoil will behave under load, both to predict total settlement and to manage differential settlement across the island's footprint. CPT measurements alone do not reach the depths needed for this scale of construction; seismic data extends the geotechnical understanding to deeper intervals where conventional in-situ testing is unavailable.

The workflow combined ultra-high-frequency and medium-frequency seismic data through pre-stack inversion to derive a continuous elastic-property field — bulk modulus, shear modulus, Young's modulus, Poisson's ratio, and density — across the site. From these elastic volumes, geotechnical parameters were derived directly: cone resistance, sleeve friction, compressibility, and soil type, all distributed in 3D rather than tied to discrete CPT locations.

Soil classification was performed across the seismic-derived elastic domains and resolved the lithologies most relevant to foundation behaviour: lignite, gas-bearing sand, limestone, sand, and clay. The CPT predictions were validated against ground-truth cone-resistance measurements at borehole locations.

Deformation-parameter estimation was carried out to depths of 800–1,000 m to inform settlement and differential-settlement assessments — depths well beyond what CPT campaigns can reach directly, which is precisely where the seismic-derived parameters add the most engineering value.