Geologic and Geotechnical Hazards for Pacific Region Floating Offshore Wind Farms

The BOEM Office of Renewable Energy has funded a study to assess the potential catastrophic geohazards, including seismic activities, landslides and tsunamigenic earthquakes, gas plumes, liquefaction, and turbidity currents, in the Pacific as threats to the design of wind turbines installed in the hazard-prone regions, and the loads imposed on the mooring and anchorage system and buried cable due to seismic activity.

This study assesses and reviews all seismic and co-seismic sources and seabed geologic components for the U.S. West Coast (California, Oregon and Hawaii), and evaluates the potential hazards on the areas already designated as potential lease sites. The goal is to help the selection of suitable sites for floating wind farms and provide a comprehensive study of potential threats on the mooring and buried cables. This study also establishes the basis for a future numerical modeling study of landslides due to earthquakes and tsunami generation from these events. To ensure the safe deployment of offshore wind projects, it is crucial to implement design standards; define requirements and regulations in earthquake-prone areas; and indicate needed safety factors related to earthquake ground motion and evaluation criteria. This is necessary to achieve an appropriate level of structural reliability for offshore wind turbines in the United States.

The objectives of this project are to provide comprehensive maps of geohazards and geological data in the designated lease blocks and indices and ranks for the blocks based on the hazards from earthquakes and historically-collected bathymetric and geologic data such as soil type. Recommendations on further suggested studies will then be provided based on identified data gaps. The aim is to help in identifying suitable site locations and assist BOEM in making their decisions on this process by providing the key elements on geohazard information and maps, regulations, and recommendations.