A major Alpine Fault rupture could leave communities in the Mackenzie District isolated, with local councillors warning that Tekapo might be split in two and cut off from critical emergency responders, according to a report presented to the Mackenzie District Council last month.
Mackenzie District Readiness and Emergency Management Plans
Mackenzie District Council emergency management officer Nils Walzel presented the report outlining new emergency response plans and district readiness to the council. During the meeting, councillors discussed the potential impacts of an Alpine Fault rupture alongside the Ostler fault zone, which runs directly through the district. According to geographical details provided, the Ostler Fault sits east of the Alpine Fault and extends approximately 65km from the Ben Ohau Range north of Twizel to the Ahuriri River in the Waitaki District.
Councillor Jan Spriggs raised concerns regarding leadership continuity if officials are trapped. “I think it would be really useful as a councillor who may actually be isolated … if there was some understanding of what might happen in that situation,” Spriggs said, noting that communications are expected to fail and bridges will likely collapse.
Self-Reliance and Local Level Preparedness
A major event on the Alpine Fault would leave local authorities largely responsible for managing their own responses and communities, according to council chief executive Angela Oosthuizen. Oosthuizen stated that if a magnitude 8 earthquake on the Alpine Fault occurs, nearly every council will be on its own. “So the message we should be sending to our communities is ‘you should be able to get through for at least a week with food and water’,” she said. “We’ve got to be prepared at the local level.”
To address infrastructural readiness, the emergency team is implementing additional operational checks across the district’s three generators located in Fairlie, Tekapo, and Twizel. Walzel noted that these measures aim to ensure proper oversight and robust fuel management. “We just want to [make] sure that there’s operational oversight and a good fuel management plan,” he said.
Infrastructure Vulnerabilities in Tekapo and Twizel
Councillors also scrutinized the structural integrity of designated civil defense and welfare facilities. Councillor Mark Adams questioned whether a permanent trailer generator could be installed at the Twizel Events Centre, which serves as the district’s designated welfare centre, pointing out that the building lacks sufficient earthquake strengthening for an emergency management facility. “Our infrastructure is not necessarily as earthquake strengthened… as one would wish for an emergency management facility,” Adams said.
Adams similarly questioned the suitability of the Tekapo Community Hall for housing the town’s generator during a seismic event, citing a lack of high earthquake strengthening. He suggested moving the generator to a more suitable location such as the recycling park, noting that an earthquake could realistically split Tekapo into two parts, leaving infrastructure on one side and the generator on the other.
Walzel responded that alternative locations remain under consideration, though the resource park already possesses necessary supporting systems. “There’s a facility to keep it under a roof… there is a solar arrangement to keep the start-up battery constantly powered, so that its always ready to be used,” Walzel said.
Addressing further infrastructural concerns, Adams questioned the resilience of key sewerage pumps. Operations and regulatory general manager Neil Jorgensen assured the council that backup measures are in place. “We have our own backup systems to enable systems to operate… that does have a generator plug, and our guys will go out and plug that in if required during an event,” Jorgensen said.
Alpine Fault Seismic Context and Probability
The Alpine Fault stretches most of the length of the South Island of New Zealand, running from Milford Sound to the north of Lewis Pass. According to data from the AF8 website, the fault carries a 75% chance of rupturing within the next 50 years. The same data estimates an 82% probability that any such earthquake will exceed magnitude 8.0, which would release 250 times more energy than the 2011 Christchurch earthquake.
Historical records indicate that the fault has experienced 27 ruptures in the last 8000 years, averaging every 300 years, with the most recent in 1717.