Representatives from 50 organisations around Otago attended the Project AF8 meeting, which took its name from the potential magnitude 8-plus earthquake believed to be brewing along the Alpine Fault.
The planning exercise was supported by the Universities of Otago and Canterbury, and GNS Science, and funded by the Ministry of Civil Defence and Emergency Management.
Otago Civil Defence and Emergency Management Group regional manager Chris Hawker said the exercise's focus was on preparing for the first week after an Alpine Fault earthquake.
Project AF8 science leader
Dr Caroline Orchiston, of the University of Otago, said that
the scenario being planned for was a 400km-long rupture along the fault, generating a magnitude-8.2 earthquake.
That would be about 10 times more powerful than last year's Kaikoura quakes, generating shaking that continued for up to five minutes.
Such shaking was expected to cause damage, landslips and liquefaction hundreds of kilometres away, she said.
Scientists had found the Alpine Fault ruptured on a ``very regular'' basis, about every 300 years, and the most recent rupture was in 1717 - 300 years ago.
There was now a 30%-50% likelihood of an Alpine Fault earthquake sometime within the next 50 years, rising to an 85% likelihood over the next 100 years, she said.
Mr Hawker said areas closer to the fault - particularly on the West Coast - would be worst affected, with significant damage to buildings and infrastructure, but the quake would create ``major challenges'' across Otago.
``Many communities will be isolated and without essential services for days or potentially weeks due to shaking, liquefaction, and landslides,'' he said.
Yesterday's exercise was focused on support for the Queenstown Lakes and Central Otago districts, but also the ``countless'' other issues to be confronted, Project AF8 programme manager Jon Mitchell said.
Workshops were being held in each South Island region until April, after which a co-ordinated South Island Alpine Fault Earthquake (Safer) plan will be prepared by mid-2018.
