Multichannel seismic and hydroacoustic data from the Maldives carbonate platform in the northern Indian Ocean document 4–8 km wide and are 70–170 m thick submarine landslides at water depths greater than 500 m, potentially associated with extensive fluid escape and the occurrence of gas hydrates. The mobilized sediments are part of giant drift bodies that consist of fine-grained carbonate ooze. Their downslope extent is located adjacent to large gateways that connect the semi-enclosed inner basin of the carbonate platform with the open Indian Ocean. Exposed at the sea-floor are headwall and translational domain of the landslides, showing different kinematic indicators typical for mass transport complexes. The submarine landslides evolved at slightly inclined slopes (20°) part of the platform slope which faces the Indian Ocean. Data show that landslide activity is ongoing. The likely trigger of slope failure is a combination of gravitational forces and the reduction of sediment shear strength moderated by fluid ascent and the destabilization of gas hydrates. Gas hydrates are suggested to play an important rule, because the top of the gas hydrate stability zone coincides with a significant steepening of the platform slope from 1-3° to 10–20°. It is therefore proposed that the dissociation of the gas hydrates, for example during sealevel lowstands might have been an additional trigger of slope failure. During sealevel highstands, gas-hydrate coating of sediment grains may facilitate low-velocity plastic deformation of the strata.
Multichannel seismic and hydroacoustic data from the Maldives carbonate platform in the northern Indian Ocean document 4–8 km wide and are 70–170 m thick submarine landslides at water depths greater than 500 m, potentially associated with extensive fluid escape and the occurrence of gas hydrates. The mobilized sediments are part of giant drift bodies that consist of fine-grained carbonate ooze. Their downslope extent is located adjacent to large gateways that connect the semi-enclosed inner basin of the carbonate platform with the open Indian Ocean. Exposed at the sea-floor are headwall and translational domain of the landslides, showing different kinematic indicators typical for mass transport complexes. The submarine landslides evolved at slightly inclined slopes (20°) part of the platform slope which faces the Indian Ocean. Data show that landslide activity is ongoing.
The likely trigger of slope failure is a combination of gravitational forces and the reduction of sediment shear strength moderated by fluid ascent and the destabilization of gas hydrates. Gas hydrates are suggested to play an important rule, because the top of the gas hydrate stability zone coincides with a significant steepening of the platform slope from 1-3° to 10–20°. It is therefore proposed that the dissociation of the gas hydrates, for example during sealevel lowstands might have been an additional trigger of slope failure. During sealevel highstands, gas-hydrate coating of sediment grains may facilitate low-velocity plastic deformation of the strata.