Submarine geohazards and mitigation concept for offshore wind

This paper presents and discusses the characteristics, mechanism, prediction and assessment of submarine geohazards with a special emphasis on liquefaction, coastal and submarine landslides, and tsunamis. Submarine landslide tsunamis are now seen from all geological environments including passive, convergent and transform margins, as well as volcanoes. The typhoons/cyclones/hurricanes-induced liquefaction is closely linked with scour and erosion at/around coastal and marine structures such as offshore wind. The cascading mechanism involving the earthquake-liquefaction-coastal and submarine landslides-tsunamis is highlighted, emphasizing the multi-phased physics of the multi-geohazards. Notably, the critical importance of the dynamics of liquefied gravity flows in coastal and submarine landslides, landslide-induced tsunamis, as well as in high-density turbidity currents is demonstrated, together with the corresponding predictions and observations, in light of their devastating consequences on human lives and critical infrastructures. The paper presents the mitigation concept for a range of submarine geohazards for offshore wind, showing novel submarine geohazards resistant design concepts for bottom-fixed and floating offshore winds for a safe sustainable development across the globe.