The opening of the NFB began when a slab roll-back was initiated beneath the New Hebrides and the island arc started its clockwise rotation.

[1] The opening of the basin was the result of the collision between the Ontong Java Plateau and the Australian plate along the now inactive Solomon–Vitiaz subduction system north of the NFB.

It is opening in a complex geological setting between two oppositely verging subduction systems, the New Hebrides/Vanuatu and Tonga trenches and hence its ocean floor has the World's largest amount of spreading centres per area.

The New Hebrides island chain itself is being deformed as buoyant features such as d'Entrecasteaux Ridge and West Torres Plateau are being subducted in this process.

NFB is the product of the asymmetric back-arc opening about a hinge point at 11°S, 165°E around which the Vanuatu chain has rotated 28° clockwise during the last 6 Ma, or 6–7.5°/Ma.

This collision reversed the direction of subduction in the Vitiaz Trench and thus initiated the clockwise rotation of the Vanuatu arc and the opening of the NFB at 8–3 Ma.

[14] It can be divided into four 120–200 km (75–124 mi)-long segments: The West Fiji area is dominated by a western and an eastern graben separated by a central plateau.

In the central plateau there is a fan-shaped system of ridges and depressions, the centre of which is occupied by a 3,000 m (9,800 ft)-deep and 10 km (6.2 mi)-wide graben.

[17] The inactive volcanic islands Mitre and Anuta are rejuvenated Vitiaz arc volcanoes that formed 2.2 Ma, probably as a consequence of a change in the motion of the Pacific plate.

Other geological structures are remnants of island arcs and back-arc basins mostly from the Eocene and Miocene, including the Vitiaz Trench and the Lau–Colville, Three Kings, and Loyalty ridges.

The region probably formed far south-west of its present location where it was subsequently rifted apart when the South Fiji Basin opened in the Early Oligocene.

From the Early Oligocene to Miocene the region was part of an arc that formed the northern margin of the Australian plate.

The NFB back-arc basin broke through this margin c. 12 Ma and has since the Late Miocene rotated the New Hebrides Arc 30° clockwise and Fiji at least 100° counter-clockwise.

[22] Beneath Tonga at a depth of 350–500 km (220–310 mi) the number of earthquakes increases dramatically while the shape of the Pacific becomes complex.

If these segments are combined and reconstructed back to their original location at the surface, they equal both the NFB and the subducted part of the Australian plate since 12 Ma in area.