The relatively small Rotomā Caldera (also known as Rotomā Embayment, Rotomā volcanic complex, and spelled Rotoma) is in the

Taupō Volcanic Zone The Taupō Volcanic Zone (TVZ) is a volcanic area in the North Island of New Zealand that has been active for the past two million years and is still highly active. Mount Ruapehu marks its south-western end and the zone runs north-eastward thro ...

in the North Island of New Zealand.

Geography

The Rotomā Caldera is located halfway between the city of

Rotorua Rotorua () is a city in the Bay of Plenty region of New Zealand's North Island. The city lies on the southern shores of Lake Rotorua, from which it takes its name. It is the seat of the Rotorua Lakes District, a territorial authority encompass ...

and town of Whakatāne, with its in filling Lake Rotomā being the easternmost in the chain of three volcanic lakes to the northeast of Lake Rotorua. The other two are Lake Rotoiti and Lake Rotoehu.

Geology

The Rotomā Caldera is immediately to the northeast of the area previously called the Haroharo volcanic complex, and now known as the Haroharo vent alignment.Okataina Volcanic Centre Geology
" ''GNS science''. Retrieved 11 June 2022. This is now regarded as part of the much larger

Ōkataina Caldera Ōkataina Caldera (Ōkataina Volcanic Centre, also spelled Okataina) is a massive, recently active volcanic caldera and its associated volcanoes located in Taupō Volcanic Zone of New Zealand's North Island. It is just east of the smaller Rotoru ...

( Ōkataina Volcanic Centre).McKinnon, M.,
Okataina caldera and its neighbours
" ''

Te Ara - Encyclopedia of New Zealand ''Te Ara: The Encyclopedia of New Zealand'' is an online encyclopedia established in 2001 by the New Zealand Government's Ministry for Culture and Heritage. The web-based content was developed in stages over the next several years; the first s ...

'', 1 May 2015. Retrieved 11 June 2022. It has been usually classified as part of this volcanic structure, but given the evidence that it is a region of structural collapse beyond the Ōkataina Caldera rim is perhaps best called an embayment. It is associated with the northern fault boundary zone (Rotoehu Fault,

Manawahe Fault The Manawahe Fault line is a seismically active area in the Bay of Plenty Region of the central North Island of New Zealand with the potential to be involved with other faults in an event. Geology North of Lake Rotoma, volcanic ignimbrite shee ...

, North Rotomā Fault, Braemar Fault, Mangaone Fault) in the Whakatāne Graben part of current rift activity in the Taupō Volcanic Zone. The caldera is likely overlying the former drainage valley that historically Lake Rotorua used before the Rotoiti eruption of the Ōkataina Caldera 47,400 ± 1500 years ago. The Rotomā volcano's most prominent feature Lake Rotomā was formed within the Rotomā caldera when lava flows following a large crater explosion blocked its outlet. The major eruption episodes were about 7412 BCE with about of material erupted from 3 different magmas from several different vents. This eruptive sequence was associated in time with ruptures in the Manawahe Fault about to the north-east. It is known that the changes in vegetation following the eruption, while significant, were short-lived. Pre-eruption forest and mire vegetation recovering to former levels within about 106 years.

References

{{DEFAULTSORT:Rotomā complex Calderas of New Zealand Taupō Volcanic Zone VEI-7 volcanoes Volcanoes of the Bay of Plenty Region