Mount Tarawera

The eruption that generated the Ōkareka Tephra has been dated to 23,535 ± 300 years before the present.[4] It had a tephra volume of about 12 cubic kilometres (2.9 cu mi) but may be less, generated in days or weeks at the most.[5] The associated eruption mountain building appears to have been at both ends of the complex and includes present features at the eastern end such as the Rotomahana Dome (434 m (1,424 ft)[1]) and Patiti Island (peak is 404 m (1,325 ft)[1] high) which is in the middle of Lake Rotomahana. Lava fields at the western end came from sources most likely buried in the Waiohau eruption, have a volume of at least 5 cubic kilometres (1.2 cu mi),[6] and would have taken several years to form.[5] The Ōkareka Embayment is a separate, but adjacent volcanic structure in the Ōkataina Caldera responsible for the Rotorua Tephra.

The Rerewhakaaitu eruption has been recently re-dated forward to 17,496 ± 462 years ago,[4] at about the time of the last glacial termination, with a tephra volume of about 7.5 cubic kilometres (1.8 cu mi).[5] Other historic sources suggested a higher volume. It involved three rhyolite magmas with a total volume of about 5 cubic kilometres (1.2 cu mi) with the Rerewhakaaitu Tephra having 15 rhyolitic fall units.[5] The Southern (1,024 m (3,360 ft)[1]) and Western (446 m (1,463 ft)[1]) Domes were formed at this time and the lava excursion of 2 cubic kilometres (0.48 cu mi)[6] again lasted for several years after the much shorter tephra phase of the eruption.[5]

The Waiohau eruption occurred 14,009 ± 155 years ago (recently re-dated backward).[4][2] The Kanakana (925 m (3,035 ft)[1]) and Eastern (529 m (1,736 ft)[1]) Domes were formed.[5] The estimated total volume of the fifteen or more Waiohau Tephra eruptions and some lava is 2 cubic kilometres (0.48 cu mi).[7] During one of the eruptions structural collapse of the then mountain occurred.[7]

Mount Tarawera erupted 1314±12 CE[8] in the Kaharoa eruption.[9][10][4] This was just a few years after the first Māori settlement about 1280 CE[11] although more wide spread settlement is now believed to have not taken place until 1320 to 1350 AD.[12] The Plinian phase of this eruption consisted of 11 discrete episodes of VEI 4[13] although there are possibly two more discrete sub-Plinian phases in a two stage eruption from at least two different vents along a 8 km (5.0 mi) long fissure.[14] The total dense rock equivalent (DRE) was at least 9.1 km³ (2.2 cu mi).[14] It distributed the Kaharoa Tephra, very low in the essential mineral cobalt (lack of cobalt is a factor in New Zealand bush sickness), from the east coast of the Northland Peninsula, down the Coromandel Peninsula and through beyond Tarawera to northern Hawke Bay at the Māhia Peninsula.[11] The total volume of material erupted was more than 5 times that of the 1886 eruption[15] and has been stated to be at least 15 km³ (3.6 cu mi) of tephra.[14] The Ruawahia (1,111 m (3,645 ft)[1]), Tarawera(874 m (2,867 ft)[1]), Wahanga (1,025 m (3,363 ft)[1]) and Crater (1,095 m (3,593 ft)[1]) Domes were formed.[5]

Volcanic crater

Shortly after midnight on the morning of 10 June 1886, a series of more than 30 increasingly strong earthquakes were felt in the Rotorua area[16] and by 2:45 am Mount Tarawera's three peaks had erupted, blasting three distinct columns of smoke and ash thousands of metres into the sky[17] At around 3.30 am, the largest phase of the eruption commenced; vents at Rotomahana produced a pyroclastic surge that destroyed several villages within a 6 kilometer radius, and the Pink and White Terraces appeared to be obliterated.[18] Recent research using mathematical modelling of events during the later Rotomahana eruption phase, is consistent with eyewitness accounts; describing it resembling a pot boiling over.[19][20]

Crumbling scoria cliffs surround the summit rift

Settlements inhabited by Ngāti Rangitihi and Tūhourangi around the Ariki arm of Lake Tarawera, including Moura, Koutu, Kokotaia, Piripai, Pukekiore and Otuapane, Tapahoro, Te Wairoa, Totarariki, and Waingongoro, were buried or destroyed. Of these, Te Wairoa is now a tourist attraction and is described as the "buried village". The official death toll was reported as 153, and many more were displaced, making the eruption the most deadly in New Zealand history.[21][22][23][24] The survivors became refugees in their own country, for generations.

The eruption was also believed to have destroyed the world-famous Pink and White Terraces. However, 125 years after the eruption a small portion of the Pink Terraces was reportedly rediscovered under Lake Rotomahana.[25] This was due to the discovery of a previously unknown 1859 survey of Lake Rotomahana by Ferdinand von Hochstetter, which was deciphered and published between 2016 and 2019. This unique primary data indicate the Pink, Black and White Terrace locations now lie along the present lake shores. There is a prospect the terraces or sections of them, may lie buried, and as a result the terraces can no longer be assumed destroyed.[26][27][28][29]