Wadati–Benioff zone

The term was named for the two seismologists, Hugo Benioff of the California Institute of Technology and Kiyoo Wadati of the Japan Meteorological Agency, who independently discovered the zones.

[8] At depths below the thickness of the lithosphere, earthquakes are no longer generated by thrusting at the interface of the two plates, because the asthenosphere is weak and cannot support the stresses necessary for faulting.

[9] In some cases, subduction zones show two parallel surfaces of seismicity separated by tens of kilometres at intermediate depths (50–200 km).

Some of the suggested instability mechanisms include dehydration embrittlement caused by the breakdown of antigorite or chlorite in a hydrated peridotite upper mantle,[12] and un-bending of the slab.

[10] Observations from seismic studies indicate that the lithospheric mantle at the intermediate depths where double Benioff zones occur is dry, which favours the proposed slab-unbending mechanism.