Earthquake and Seaquake Analysis for a 15MW Semi-Submersible Floating Offshore Wind Turbine (FOWT)

It is important to investigate the possible impact of earthquakes on Floating offshore Wind Turbines (FOWTs) to be installed near volcanic zone, such as Ring of Fire in California. In this study, we propose a procedure for numerical implementation of earthquake and seaquake loads on FOWTs. Seaquake potential satisfying 3D Helmholtz equation is calculated by hybrid integral equation method. The pre-calculated seaquake load time-series is inputted to fully coupled aero-servo-hydro-mooring-dynamic analysis program. A three-column 15MW semi-submersible FOWT is used with El Centro past earthquake record scaled based on the spectral matching method targeting one offloating wind farm leasing areas (Morro Bay, California). Numerical analysis shows that incorporation of seaquake load is insignificant in platform motion and mooring tensions responses, but nacelle z-acceleration can be appreciably increased due to high frequency content of earthquakes and seaquake loads.