Re­search­ing Auck­land city’s next erup­tion


Boil­ing lava is spew­ing from a moun­tain in south Auck­land, rocks are be­ing thrown through the air and a thick cloud of ash cov­ers the sky - would you know what to do?

This was the ques­tion be­hind new re­search from GNS Sci­ence, which an­a­lysed what would hap­pen if one of Auck­land’s 52 vol­ca­noes erupted.

The re­search pa­per, re­leased in the Jour­nal of Vol­canol­ogy and Geother­mal Re­search this week, is based on a hy­po­thet­i­cal twom­onth-long pe­riod of un­rest and erup­tion near Man­gere Bridge, in south Auck­land. Geo­sci­en­tists from GNS Sci­ence, the Univer­sity of Can­ter­bury and Massey Univer­sity looked at the im­me­di­ate haz­ards of an erup­tion and the on­go­ing im­pact an erup­tion could have on Auck­land’s crit­i­cal in­fras­truc­ture.

Lead au­thor of the pa­per, Natalia Deligne, said that while sci­en­tists had no idea where the next erup­tion would be, they could be bet­ter pre­pared by look­ing at how to re­spond.

Their erup­tion sce­nario in­cluded a new vol­canic cone be­ing cre­ated, a se­ries of small vol­canic earth­quakes, ash fall, lava flows, and rocks be­ing hurled into the air - all of which were con­sid­ered re­al­is­tic pos­si­bil­i­ties for an erup­tion in Auck­land, Deligne said.

Deligne, a vol­canic haz­ard and risk mod­eller at GNS Sci­ence, said the wider study looked at fuel, roads, rail, ports, avi­a­tion, wa­ter sup­ply and telecom­mu­ni­ca­tions to get a dy­namic pic­ture of how Auck­land would hold up.

The Auck­land vol­canic field is the most densely pop­u­lated field of its type in the world. The field is 250,000 years old and there have been 55 recorded erup­tions, the most re­cent be­ing Ran­gi­toto around 600 years ago.

Most Auck­land vol­ca­noes are mono­genetic, mean­ing they only erupt once, so it is very likely that the next vol­canic vent in Auck­land will erupt in an en­tirely new lo­ca­tion. No spa­tial pat­terns have been de­tected within Auck­land’s vol­canic field - the old­est and youngest vol­ca­noes, Pupuke and Ran­gi­toto, are next to each other - so the lo­ca­tion of a fu­ture erup­tion can­not be pre­dicted through pattern.

While they can’t say where the next erup­tion will be, GNS sci­en­tists say they are cer­tain that there will be a fu­ture erup­tion.

nd 2m-high tsunami waves were pre­dicted for the Manukau Har­bour shore­line.


Ran­gi­toto is Auck­land’s youngest vol­cano, hav­ing erupted 600 years ago.

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