The trench turns west north of the Tonga Plate and becomes a transform fault zone.

The Tonga plate is seismically very active and is rotating clockwise.

The Tonga Plate is a small southwest Pacific tectonic plate or microplate.

The earthquake occurred in the southwest of the Samoa Islands, along the Tonga Plate boundary.

The Tonga plate is subducting the Pacific plate along the Tonga Trench.

This plate is sandwiched between the Pacific Plate to the north, the very unstable Tonga Plate to the east and the Australian Plate to the west.

Subduction of the Pacific Plate beneath the Australian Plate and Tonga Plate, forming the complex New Zealand to New Guinea subduction/transform boundaries.

The trench lies at the northern end of the Kermadec-Tonga Subduction Zone, an active subduction zone where the Pacific Plate is being subducted below the Tonga Plate and the Indo-Australian Plate.