Also known as the Benioff-Wadati zone.
In geology and seismology, the Benioff zone is a zone of the upper mantle, in which earthquakes occour when a lithospheric plate is subducted.
This zone is seismically active and is the focal point of subduction earthquakes: originally thought to be one plane, recently it has been recognized as two distinct planes. The less pronunced upper zone delineates the top of the downgoing plate, with the main lower zone 10 - 20 kilometres below. As the subducted plate is compressed from the depth, earthquakes occour due to the internal deformation of the plate.
The lower zone can extend to a depth of up to 700 kilometres below the Earth's surface, but 300 - 400 kilometres is more common.
The Benioff-Wadati zone is named in honour of the seismologists Kiyoo Wadati and Hugo Benioff.