Erup­tion would crip­ple city


A vol­canic erup­tion could bring Auck­land to its knees, crip­pling trans­port net­works and dis­plac­ing al­most one-third of its pop­u­la­tion.

Sci­en­tists from the Univer­sity of Can­ter­bury have mod­elled what would hap­pen to the city’s trans­port net­works if there was an erup­tion.

The study looked at a hy­po­thet­i­cal two-month-long dis­as­ter cen­tred near Man­gere Bridge, south of the CBD. It is one of a se­ries of stud­ies us­ing this sce­nario to model the im­pact of an erup­tion on Auck­land.

The study, re­leased on Tues­day, found Auck­land’s dif­fi­cult ge­og­ra­phy would limit trans­port and evac­u­a­tion routes.

The most sig­nif­i­cant dis­rup­tion across all trans­port net­works would hap­pen around six days be­fore the erup­tion, be­cause of the es­tab­lish­ment of evac­u­a­tion zones.

These would block cru­cial north-south links across Auck­land, and at times cause up to 435,000 res­i­dents to be dis­placed.

Re­searcher Thomas Wil­son said any erup­tion could have ‘‘po­ten­tially big con­se­quences’’ for the city’s ur­ban area.

‘‘Auck­land is on an isth­mus, so there’s quite a small land area where a num­ber of dif­fer­ent in­fra- struc­ture net­works run through. A mass evac­u­a­tion puts a lot of pres­sure on Auck­land’s trans­port.’’

The team found that most phys­i­cal dam­age to road and rail would hap­pen from the vol­canic erup­tion it­self, de­stroy­ing any­thing within a 0.5 to 2.5km ra­dius, but with lit­tle im­pact from earth­quakes lead­ing up to the erup­tion.

Auck­land Air­port would not be di­rectly af­fected by phys­i­cal dam­age, but would have re­stricted ac­cess due to evac­u­a­tion zon­ing and airspace re­stric­tions, forc­ing lim­ited do­mes­tic and cargo flights to re­di­rect to When­u­a­pai and Ard­more Aero­drome.

Vol­canic ash de­posits on roads and rail lines would cause dis­rup­tion for more than a month af­ter the erup­tion, un­til clean-up and re-en­try to most evac­u­a­tion zones was com­pleted.

The study said the most im­por­tant fac­tors for keep­ing the trans­porta­tion network open would be re­mov­ing vol­canic ash from bot­tle­neck ar­eas such as bridges.

The last erup­tion within the Auck­land vol­canic field hap­pened at Ran­gi­toto Is­land around 500 years ago.


Ran­gi­toto Is­land was the scene of Auck­land’s most re­cent vol­canic erup­tion.

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