Hjort Trench

The Hjort Trench is a linear topographic depression south of Macquarie Island in the southwest Pacific Ocean. Geologically, the depression is considered to be the seafloor expression of an ocean-ocean subduction zone, where the Australian plate is thrusting beneath the Pacific Plate. As the southernmost portion of the Macquarie Ridge Complex, the Hjort Trench lies in an area of diagonal convergence produced by the transform fault evolution of the Emerald Fracture Zone. Frequent seismic events, most less than deep, characterize the transpression along this plate boundary.
Geomorphology.
The deepest point of Hjort Trench is approximately below sea level. To the east, the Hjort ridge follows the general curve of the trench, separating the trench from the Hjort Plateau.
Incipient subduction.
The Hjort Trench lies in an area of transpression where the plate boundary transitions from a transform boundary to a convergent one. As such, this region provides an example of how a transform boundary with a vertical or near-vertical transform fault becomes an area of under-thrusting.