Deep seismicity and modes of deformation in Tonga subduction zone

Abstract
The geometry of deep ( greater than 400 km) earthquakes in the subducting western edge of the Pacific plate, when related to the local distribution of seismic activity, reveals a complex pattern of planes of shear failure, enabling the modes of deformation by which the descending plate shortens and thickens to be identified. The deepest part of the slab is displaced laterally, suggesting that it fails to penetrate the discontinuity at 670 km