The initiation of subduction remains one of the unresolved challenges of plate tectonics.
In spite of its importance, it is unclear how subduction is initiated.
Cloos and Saunders et al. have shown that large oceanic plateaus cannot be subducted. Such thick plateaus resist subduction, jam the trench and accrete to the arc.”
It is disturbing that the proposed, exceedingly large differential movements between continents and ocean basins (especially where much unconsolidated sediment is involved) are not obvious. ... The present simple continental-margin model diagrammed with essentially rigid slabs does not relate well to observational data, and its value as a framework for interpreting observed structures of the continental margin is diminished by the large gap between theory and observation.” Roland von Huene, “Structure of the Continental Margin and Tectonism at the Eastern Aleutian Trench
… slippage of the oceanic crust beneath an overlying trench fill is unsupported by observational as well as theoretical data …