Submarine Landslides caused by Seamounts entering Accretionary Wedge Systems

Jonas B. Ruh (1)

1 iSTeP - Institut des Sciences de la Terre de Paris

Seamounts entering active subduction zone trenches initially collide with the frontal sedimentary accretionary wedges resulting in severe deformation of the overriding plate. A typical feature of this deformation is the occurrence of submarine landslides due to gravitational instabilities. Such landslides have been reported from the Middle America and the Hikurangi trench and potentially generate tsunami waves. Yet, the dynamics of accretionary wedges during seamount indentation and landsliding as a mechanical response in particular have not been investigated quantitatively. Here, I apply 3D high-resolution numerical experiments to show that the topographical evolution of an accretionary wedge is mainly depending on the volume of the entering seamount and not on its height. Submarine landslides only occur if seamounts are not completely buried by the sedimentary sequence, where the volume of avalanches can be roughly correlated with the seamount volume overtopping the incoming sediments.

Domaines: Sciences de la Terre

Jonas B. Ruh. Submarine Landslides caused by Seamounts entering Accretionary Wedge Systems. Terra Nova, 2016, 28 (3), pp.163-170 ⟨10.1111/ter.12204⟩. ⟨hal-01289133⟩