Sea-level fluctuations control the distribution of highly liquefaction-prone layers on volcanic-carbonate slopes
|Author(s)||Sultan Nabil1, Jouet Gwenael1, Riboulot Vincent1, Terzariol Marco1, Garziglia Sebastien1, Cattaneo Antonio1, Giraudeau J.2, Jorry Stephan1|
|Affiliation(s)||1 : Geo-Ocean, UMR6538, Ifremer, CNRS, UBO, UBS, 29280 Plouzané, France
2 : Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), UMR 5805, Université de Bordeaux, CNRS, 33615 Pessac CEDEX, France
|Source||Geology (0091-7613) (Geological Society of America), 2023-04 , Vol. 51 , N. 4 , P. 402-407|
Understanding and quantifying the hazards related to earthquake-induced submarine liquefaction and landslides are particularly significant offshore of tropical volcanic-carbonate islands, where carbonate production competes with volcanism to create highly contrasted lithological successions. To improve the detection of liquefaction-prone layers, we analyzed physical properties and mineralogy and performed 70 dynamic triaxial tests on 25 sediment cores offshore of the eastern side of Mayotte (Comoros archipelago in the western Indian Ocean) in an area that has experienced significant seismicity since 2018. We found that the main parameter controlling the liquefaction potential offshore of Mayotte is the presence of low-density layers with high calcite content accumulating along the slope during lowstands. This phasing with sea-level fluctuations implies a significant recurrent geohazard for tropical volcanic-carbonate islands worldwide. Furthermore, the relationship we found between the cyclic resistance of sediment and its density and magnetic susceptibility represents a time-effective approach for identifying the hazards related to earthquake-induced liquefaction.