Varies in your presuppositions/worldview. In the case of Young Earth Creationism, run away subduction (Catastrophic Plate Techtonics) explains the tectonic activity during and after the flood. This model was created by John Baumgardner. In the old earth uniformitarianismistic view it is the latest in the 300 million year cycle of collisions of techtonic plates. Each cycle has the continental plates crashing into each other. This can not be effectively modeled due to the unobservable past.