An international scientific team recovered the clay in May, during the first-ever drilling project across a recently shattered subduction zone. Eastward of Japan,two of Earth,s massive crustal fragments, called tectonic plates ,bash into each at a subduction zone-where the Pacific plate slides, protesting and groaning , under the Okhotsk Plate.The word,s biggest earthquakes(those stronger than magnitude-9)strike on subduction zones.