What would a big Alpine Fault quake look like?

Just-released videos have shown what would happen in the event of a major quake along the South Island's big-risk Alpine Fault.

The four videos have been produced by Government-funded Project AF8, the South Island-wide effort to co-ordinate planning and preparations for a large event along the fault boundary, which runs along the spine of the South Island.

On average, earthquakes of magnitude 7.5 or larger strike along the Alpine Fault every 300 years - a relatively frequent rate in geological terms - and scientists say it's highly likely the next big quake will happen in the lifetime of today's population.

It last ruptured around 300 years ago - producing a massive earthquake of about magnitude 8.0 - and has an average 30 per cent probability of rupturing in the next 50 years.

GNS Science maintains the rupture would produce one of the biggest earthquakes since European settlement of New Zealand and have a "major impact" on the lives of people across the country.

"Some of New Zealand's best scientific minds from universities, Crown Research Institutes and GNS Science have worked together to produce a credible scenario for what will happen with the next major earthquake on the Alpine Fault," said Project AF8 Steering Group chair Angus McKay, from Emergency Management Southland.

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

The new videos coincide with the completion of the draft South Island Alpine Fault Earthquake Response (SAFER) framework to co-ordinate civil defence, emergency services, lifelines utilities and other partner agencies.

"The next step is to plan in more detail for a coordinated response to those impacts and the extensive disruption they will cause," McKay said.

"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."

Project AF8 will begin implementing its finalised framework from July.