Adil Abass LoneFor most of its history, offshore wind grew in the North Sea, where earthquakes barely enter the design conversation. That is changing fast. New projects across the Asia-Pacific region are being planned in some of the most seismically active waters on Earth. In July 2026 the certification body DNV released a new edition of its recommended practice for the seismic design of wind power plants, DNV-RP-0585.
Wind projects are increasingly developed in regions where earthquake loading is a primary design driver.
That shift, from "check it at the end" to "primary design driver", is the subject of this month's post.
What changed in the 2026 edition
According to DNV's announcement, the update includes:
- improved guidance on seismic analysis methods and modelling requirements;
- updated recommendations on soil–structure interaction and foundation damping;
- clarifications on seismic loading, ground-motion selection and post-processing;
- guidance on identifying the critical design positions inside large wind farms;
- new recommendations for installation vessels operating in seismic regions;
- a new appendix summarising Japan's local seismic design requirements.
DNV says the revision draws on recent projects and the ACE 2-EVOLUTION joint industry project, which involves more than 20 companies across the offshore wind supply chain. As DNV's Marcus Klose put it, effective seismic design "requires close alignment between turbine, foundation and geotechnical disciplines".
Why monopiles are not just tall buildings in water
A monopile-supported turbine is a slender, top-heavy structure: a heavy rotor and nacelle on a tall tower, on a single large-diameter steel pile driven into soft marine sediments. In an earthquake, at least three things make it different from an onshore structure.
1. The seawater moves too
The water around the pile interacts with the structure and with the seabed. It is often reduced to a simple "added mass". However, water is a medium of its own: it changes how seismic energy reaches and loads the foundation. Treating soil, water and structure as one coupled system is fluid–soil–structure interaction (FSSI).
2. Seismic waves don't always arrive from directly below
Design practice usually assumes that seismic waves travel vertically upward through the soil. For shallow or nearby earthquakes, waves can arrive at an angle (oblique incidence). This changes the motion at the seabed and the forces along the pile.
3. Water depth and soft sediments shape the shaking
Soft marine sediments can amplify ground motion. The water column adds its own effects, and these change with depth. A design checked at one water depth may not represent a turbine a few kilometres further offshore.
These three mechanisms are exactly what my co-authors and I examined in our recent paper in Structures. We built coupled numerical models in OpenSeesPy to study how they govern the seismic demand on monopile foundations (Lone et al., 2026). It is encouraging to see industry guidance now giving more attention to soil–structure interaction and ground-motion selection, because these are where the simplest assumptions can mislead.
What is still open
Updated guidance is a big step, but several questions remain open in research and practice:
- How far should we go with coupling? Fully coupled FSSI models are expensive. When is a simpler added-mass approach good enough, and when is it unsafe?
- Which input motions? Most recorded earthquake motions come from land stations. How should engineers pick and adjust motions for a site under tens of metres of water?
- Floating wind. Floating turbines are moored rather than fixed to the seabed. Their seismic behaviour, including effects transmitted through the water, is much less studied than that of fixed foundations.
- The whole farm, not one turbine. Substations, export cables and installation vessels are exposed too. A wind farm is a system, and its seismic resilience depends on its weakest link.
Questions for you
- If you design or assess offshore foundations: do you model the surrounding water explicitly, use added mass, or ignore it? Why?
- Have you seen a project where the angle of incoming seismic waves changed the design outcome?
- What is the biggest barrier to using coupled soil–water–structure models in practice: computing time, software, lack of data or code requirements?
- Which open problem in offshore earthquake engineering should I write about next?
References
- Lone, A. A., Li, N., Zhang, K., Rasheedy, B. A., & Al-Shaebi, R. (2026). Fluid–soil–structure interaction under oblique seismic incidence: Mechanisms governing offshore wind turbine foundation demand. Structures, 94, 113318. doi:10.1016/j.istruc.2026.113318
- Riviera Maritime Media (3 July 2026). DNV updates seismic design guidance as wind expands into earthquake-prone regions. rivieramm.com
- Offshore Engineer (2026). DNV updates seismic guidance for offshore wind. oedigital.com
- DNV. DNV-RP-0585: Seismic design of wind power plants, 2026 edition.
Views expressed here are my own and do not represent Tianjin University or my co-authors.