Big Alpine Fault rupture due in the next century or two

The Alpine Fault is a big feature of South Island geography and seismic activity. It last ruptured in 1717 and there is a big earthquake, on average, about every 300 years, but the times vary so there is thought to be about a 30% risk of the next ‘Big One’ in the next fifty years.

When I was woken up by an earthquake in the middle of the night on 4 September 2010 I wondered if it was ‘the big one’ – it was big enough but that was centred close to Christchurch.

This image clearly shows the fault running up the West Coast, where the Australian plate dives under and drives up the Southern Alps which line along the rising edge of the Pacific Plate.

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

Stuff has the latest information on this: Videos show devastating impact across South Island if Alpine Fault ruptures

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.

That sounds dramatically imminent, but the intervals have actually varied between 140 and 510 years, so it may or may not happen in our lifetimes.

The Stuff has the latest videos.

Extensive details are at Project Alpine Fault 8

The Alpine Fault is the biggest but just one of many fault lines affecting New Zealand. This is a few years old but is a good look at plate tectonics in New Zealand:

Dunedin is about as far as you can get in the South Island from the fault but when the big one strikes it is certain to be felt here (we feel larger Fiordland earthquakes as well as the bigger Christchurch quakes) and it is likely to have  major effects across the South Island, and also in the lower North Island.