Hoe groot deze was zal nog moeten blijken. Die van 1108 was iig enorm, met een koelend effect op het klimaat en mogelijk is toen de caldera gevormd. Gezien de grootte daarvan zal dat zeker een VEI 6 geweest zijn.
Van wikipedia:
The volcano itself is a submarine volcano that breached sea level in 2009 due to a volcanic eruption and lies underwater between two islands, Hunga Tonga and Hunga Ha?apai, which are respectively the remnants of the western and northern rim of the volcano's caldera.[3][9] The caldera is roughly 150 m below sea-level, and rises 2000 m from the sea-floor.[10] The two islands (part of the Ha?apai group)[11] are about 1.6 km (0.99 mi) apart,[12] and each is about 2 km (1.2 mi) long and composed largely of andesite.[5][6] This andesite tends to be of the basaltic type.[13] Hunga Tonga reaches an elevation of 149 m (489 ft), while Hunga Ha?apai comes to only 128 m (420 ft) above sea level.[3] Neither island is large: Hunga Tonga was roughly 390,000 m2 (0.15 sq mi) and Hunga Ha?apai 650,000 m2 (0.25 sq mi) in size before they were connected.[14] They are much smaller after the 2022 eruption. Neither island was developed due to a lack of an acceptable anchorage, although there were large guano deposits on each island.[11][15][16]
Samples from the islands suggest a long eruptive history.[10] One pyroclastic flow was dated to 1040–1180 CE, correlating to ash deposits found on Tongatapu, and to an unknown tropical eruption in 1108 CE that had produced 1°C of global cooling.[10] The caldera is believed to have been formed by this eruption.[10] Submarine eruptions at a rocky shoal – about 3.2 km (2.0 mi) southeast of Hunga Ha?apai and 3 km (1.9 mi) south of Hunga Tonga – were reported in 1912 and 1937.[3] Another eruption occurred from a fissure 1 km (0.62 mi) south-southeast of Hunga Ha?apai in 1988.[3]
