Abstract
Offshore wind farms are a collection of offshore wind turbines (OWTs) and are currently being installed in seismically active regions. An OWT consists of a long slender tower with a top-heavy fixed mass (Nacelle) together with a heavy rotating mass (blades) which makes the structure dynamically sensitive. They are constantly exposed to variable environmental wind and wave loads, and in seismic zones, other loads will also be imposed momentarily. The paper aims to highlight the issues associated with seismic design including liquefaction. The main conclusions are: (a) Liquefaction poses a challenge to monopile supported foundations as there are chances of significant tilt; (b) Jacket is a better option as the load transfer is through push-pull action; (c) Floating systems are better in seismic zones due to the fact that minimum inertia loads are transferred through the cables. However, floating can be potentially vulnerable to large fault ruptures.