Dr Caroline Orchiston explains the Alpine Fault and the damage the earthquake will have.

Video simulations demonstrate widespread destruction across the South Island if New Zealand's most dangerous fault line ruptures, and there's evidence the country is due for another big one.

Project Alpine Fault Magnitude 8 (AF8) released a series of videos on Wednesday, warning there's compelling geological evidence to show it produces a significant earthquake of magnitude eight or greater every 300 years on average.

The last rupture was believed to have happened in 1717.

Supplied Project AF8 have been preparing for a severe earthquake on the Alpine Fault for two years.

The Alpine Fault runs almost the entire length of the South Island, and an earthquake there will be felt by much of the country.

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* Preparing for the big one on the Alpine Fault

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Shaking near the epicentre, not far from Haast, would be unlike any felt in modern New Zealand history.

EMSOUTHLAND/YouTube EPL Ltd owner Tom Thomson talks about the challenges he faced after the February 2011 earthquakes in Christchurch.

ProjectAF8 is a South Island-wide effort to co-ordinate planning and preparation for a severe earthquake on the fault.

It released the four two-minute videos to mark two years of work.

Project AF8 Steering Group chairman Angus McKay, from Emergency Management Southland, said some of New Zealand's best scientific minds had worked together to produce a credible scenario for what would happen with the next major earthquake on fault line.

EMSOUTHLAND/YouTube Explanation of how Civil Defence will respond to a significant emergency and how to stay prepared.

"We have used that scenario to work with our partners to identify the foreseeable impacts on communities and critical infrastructure across the South Island," he said.

"The next step is to plan in more detail for a coordinated response to those impacts and the extensive disruption they will cause. Helping people to understand what an Alpine Fault earthquake will mean for them, their families and communities will be a central part of our next year's work."

A companion set of longer videos provide more in-depth detail of the science underpinning ProjectAF8, which is funded by the Ministry of Civil Defence & Emergency Management and through the Resilience to Nature's Challenges Fund.