It defines the south-western limit of the North Fiji Basin (NFB) and is an area of unique range in volcanic geochemistry,[2] which transpires to have been due partially to a new, previously unrecognised, subduction zone.

[5] The West Matthew volcano had its the most recent eruption in 1956, still had steam admissions in 1983, having formed a new volcanic cone from below the sea surface in the last 80 years.

[9] The sampled lavas are less than a million years old and suggest magma generation involves contributions from adakitic, sediment and back arc-basin basalt (BABB) melt components.

[2] An analogy has been noted with the adakitic andesites on the Solander Islands in another very young subduction system related to the Puysegur Trench south of New Zealand.

[9] At 3 million years ago were events that lead to formation of the present Australian plate and the major opening of the NFB shifted to its present-day east–west direction along the north–south-oriented Central Spreading Ridge.