Auckland Volcanic Field
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Within a radius of about 20km centred on Auckland city there are 49 discrete volcanoes; this area is referred to as the Auckland Volcanic Field. The last eruption in this area was approximately 600 years ago and while the chance of another eruption may be small it is still possible that an one will occur.
Most of the volcanoes in Auckland are small cones less than 150m in height that grew from eruptions which lasted only a few months to a few years. In some cases only a single cone resulted from the eruption but some eruptions created adjacent cones as well. Aucklands volcanic field is referred to as monogenetic which means that each time there has been an eruption it has occurred at a new location. Each eruption is the result of a single batch of magma rising from its source in the mantle about 100km beneath the city.
The monogenetic nature of Auckland’s volcanoes means that in the event of an eruption, rather than one of the existing volcanoes becoming active, a new volcano will form. Because of this, a hazard map based on any one location cannot be created and the entire field has to be considered as under threat of a future eruption.
Although it is at least 600 years since the last eruption in the Auckland volcanic field, there is every reason to expect an eruption may occur in the future. These eruptions are likely to be on a small scale compared with some overseas eruptions, but because the city of Auckland is built on and around potential eruption sites the effects are likely to be serious.
For more detailed info on the field, see: http://www.gns.cri.nz/what/earthact/volcanoes/nzvolcanoes/aucklandprint.htm
See also: Volcanoes
