Particle crushability’s role in liquefaction: insights from Mayotte submarine slopes

Since 10 May 2018, a significant number of volcanic and seismic events have been recorded in Mayotte, in the Comoros archipelago of the Indian Ocean. Detailed bathymetry of Mayotte’s eastern regions has uncovered steep underwater slopes. A recent study in the area investigated liquefaction-prone layers associated with low sea-level depositions. However, the reason for the presence of such ‘weak zones’ remained unknown. In the present study, samples from Mayotte’s slopes are examined to investigate the reason for liquefaction at the particle scale of such layers. The results show that biogenic particles in naturally sedimented environments can be crushed under cyclic or static loading even with large amounts of fines. In the case of Mayotte’s slopes, the external loading threshold was found to be 500 kPa under K₀ conditions. These findings highlight the complex behaviour of biogenic-dominant sediments, their impact on classification and overall behaviour, and their potential implications for the design of wind farms.