sentences:  Beneath southern IBM, found a DSZ lying 80 km and 120 km deep, with the two zones separated by 30 35 km.Earthquake focal mechanisms indicate that the upper zone, where most events occur, is in downdip compression, while the lower zone is in downdip extension.This DSZ is located at a depth where the curvature of slab is greatest; at greater depths it unbends into a more planar donfiguration.