<Li> Subduction zones pose significant threats to lives, property, economic vitality, cultural and natural resources, as well as quality of life . The tremendous magnitudes of earthquakes or volcanic eruptions can also have knock - on effects with global impact . </Li> <P> Subduction zones have also been considered as possible disposal sites for nuclear waste in which the action of subduction itself would carry the material into the planetary mantle, safely away from any possible influence on humanity or the surface environment . However, that method of disposal is currently banned by international agreement . Furthermore, plate subduction zones are associated with very large megathrust earthquakes, making the effects on using any specific site for disposal unpredictable and possibly adverse to the safety of longterm disposal . </P>

Basalt is pushed into the crust by subduction