39 / 2025-04-24 11:27:47

Projected Increase in Wave-induced Liquefaction Risks under Climate Change-induced Severer Wave Conditions

This paper discusses the potential for increased liquefaction risk in seabed along the Japanese coast
due to more severe wave conditions caused by climate change. A simple and practical assessment
method for wave-induced liquefaction was applied, utilizing Ocean Wave Information near the
Japanese coast (NOWPHAS). The results for the current climate, based on the observed wave
heights from NOWPHAS between 2015 and 2021, indicate that liquefaction could occur in a sandy
seabed at water depths of up to 50 meters, and in a silt bed at water depths of up to 75 meters.
With a 4% wave height increase as projected by the Japanese Ports and Harbours Bureau, the water
depths at which liquefaction could occur may increase only slightly by 5m. In contrast, under a
more extreme yet possible scenario with a 30% increase in wave height, the water depths of
liquefaction risk increase significantly by approximately 15–20 m. Namely, liquefaction could
occur in sand beds at water depths up to 65 meters and in silty beds at water depths up to nearly
100m. This suggests that liquefaction is likely to occur in the seabed of loose sands and silts around
anchors for floating offshore wind turbines which are typically installed at water depths beyond
50 meters, potentially causing instability in the foundations of floating offshore wind and cables,
as well as significant scour and erosion around them.