Kuwae is a submarine caldera between the Epi and Tongoa islands in Vanuatu. Kuwae Caldera cuts through the flank of the Tavani Ruru volcano on Epi and the northwestern end of Tongoa.

Kuwae Caldera
Shepherd Islands and associated underwater volcanoes.
Highest point
Elevation	–2 m (–6 ft) avg less than –400 m (–1,312 ft) [1][2]
Listing	List of volcanoes in Vanuatu
Coordinates	16°49′45″S 168°32′10″E[1]
Geography
Location	Shepherd Islands, Vanuatu
Geology
Mountain type	Caldera[1]
Volcanic arc/belt	New Hebrides arc[1]
Last eruption	February to September 1974[1]

The submarine volcano Karua, one of the most active volcanoes of Vanuatu, is near the northern rim of Kuwae Caldera.

Eruptive history

The Tongoa and Epi islands once formed part of a larger island called Kuwae. Local folklore tells of a cataclysmic eruption that split this island into two smaller islands with an oval 12 x 6 km caldera in between (but the story tells of an eruption south of Tongoa[2]). Collapse associated with caldera formation may have been as much as 1.1 km in an eruption assigned to the 13th century by radiocarbon dating of local deposits.[3] Around 32–39 km³ of magma was erupted, making the Kuwae eruption one of the largest in the last 10,000 years.[4]

The eruption is now believed to have taken place in the 1450s where at least two major eruptions unassigned definitely to a volcano took place. The first eruption appeared to be more likely to have been in the northern hemisphere but platinum deposits in sediments worldwide are consistent with a date of 1452/3. [5][6] Composition studies suggest the later 1458 eruption is unlikely to have been from Kuwae.[7]

In Antarctic and Greenland ice cores, a major eruption or series of eruptions is revealed as a spike in sulfate concentration, showing that the release in form of particles was higher than any other eruption since.[8] Also, analysis of the ice cores pinpointed the events to commence in late 1452 or early 1453.[8] However later higher resolution work revealed that the 1452/1453 event was separate to a large event that took place before late 1458. [9][5] The volume of expelled matter is more than six times larger than that of the 1991 eruption of Mount Pinatubo and would have caused a volcanic winter, a severe cooling of the entire planet the following three years. The link between the sulphur spike and the Kuwae caldera is questioned in a 2007 study by Károly Németh, et al. that could not identify local tephra deposits laid down in the 1450s and proposed the Tofua caldera as an alternative source candidate.[2]

Recent activity

Since its most recent historic large eruption, Kuwae caldera has had several smaller eruptions ranging from 0 to 3 on the Volcanic Explosivity Index (VEI). The latest confirmed eruption occurred on 4 February 1974 ± 4 days. It had a VEI of 0, and was a submarine eruption that formed a new island.[1]

Islands have regularly formed in Kuwae caldera.[1] The 1897–1901 eruption built an island 1 km long and 15 m high. It disappeared within 6 months. The 1948–1949 eruption formed an island and built a cone 1.6 km in diameter and 100 m high. That island also lasted less than one year. All the islands have disappeared from wave action and caldera floor movements. In 1959, the island reappeared for a short time and again in 1971. The last structure remained an island until 1975.[10]

Activity at present at Kuwae is confined to intermittent fumarole activity, which stain the water yellow. Over the top of the volcano hydrogen sulfide bubbles reach the surface.[11]

See also

• Timeline of volcanism on Earth

References

Further reading

• Witter, J B; Self, S (2007). "The Kuwae (Vanuatu) eruption of AD 1452: potential magnitude and volatile release". Bulletin of Volcanology. 69 (3): 301–318. Bibcode:2007BVol...69..301W. doi:10.1007/s00445-006-0075-4. S2CID 129403009.
• "Research project—Geological Evidence and Oral History of Tsunamis in Vanuatu". UNSW Australian Tsunami Research Centre. Archived from the original on 2011-02-19.

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