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.