It is claimed by some that the reason for gaps in chains of volcanoes generated by plate subduction is that some parts of the plate dive deep into the mantle and generate magma plumes, while other parts of the plate continue in an almost horizontal direction and therefore don't create magma plumes, hence the lack of volcanoes. Where one part of a plate continues almost horizontally while an adjacent section is driven down into the mantle, wouldn't that cause a violent fracture of the plate, and if not, why not?
Push a sheet of cardboard along a table top so that the leading edge of the cardboard overlaps the edge of the table, then grab a bit of cardboard and force it to descend. It will either carry the rest of the cardboard down with it, or it will break. I know that plates are not made of cardboard, but that's the best analogy I could think of to illustrate the principle. A similar fracture in an oceanic plate would surely be quite violent.