A subduction zone is one type of boundary between two plates of the earth's crust. One plate, which is less dense, slides up over the edge of the other as the plates move. This zone is an area that is prone to geologic instability.

Theory

Plate tectonic theory describes the Earth's lithosphere (the crust and the uppermost mantle) as individual plates that move as a result of heat convection from the mantle. These plates collide with each other along a boundary.

Features

A subduction zone features a convergent boundary where two lithospheric plates collide. The older heavier plate descends into the athenosphere (upper mantle), forming a trench that can be several miles deep, up to a thousand miles long, and up to 70 miles wide.

Significance

Instability of the plates at a subduction zone creates severe earthquakes and intense volcanic activity. Cities near a subduction zone require earthquake monitoring systems.

Geography

New Zealand is the location of the world's youngest subduction zone, where the Pacific plate is driven underneath the Australian plate. Along the Cascadia subduction zone, the North American plate dives under the Juan de Fuca plate.

Considerations

Subduction zones have been considered as sites to house nuclear waste, but currently this method is banned by international agreement.

Source:

Plate Tectonics: Subduction Zones

Science Daily: New Zealand's Subduction Zones

The Pacific Northwest Seismic Network: The Cascadia Subduction Zone

Resource:

World Nuclear Association: Disposal at a subduction zone