They looked to compare the density of subducting slabs at that time with the density of the surrounding mantle, the difference of which would determine how far slabs would have sunk. (sciencedaily.com)
Geophysical data, they note, demonstrate that India's basement rock flexes and slides beneath the Himalaya much like the earthquake - ridden subducting oceanic crust. (scientificamerican.com)
In contrast, off the coast of central Oregon, the thick layer of subducting sediments are less compact, with water in the pore space between the grains. (sciencedaily.com)