[Reprinted from stuff website]
Landslides would close major highways for up to six months, isolating communities and limiting food supplies across the South Island in the event of an Alpine Fault rupture.
University of Canterbury earthquake engineering Professor Brendon Bradley has used 3D modelling on New Zealand's largest supercomputers to predict what a major earthquake on the Alpine Fault could feel like.
He wants to raise awareness, not alarm, so people can be fully prepared.
The central and southern parts of the Alpine Fault run for about 400 kilometres up the spine of the South Island, and are about 40 times longer than the fault responsible for the fatal February 2011 earthquake in Christchurch.
GNS science said there was a 30 per cent chance of a large earthquake on the Alpine Fault in the next 50 years. It could cause horizontal movement of up to eight metres.
In Christchurch, the shaking from an Alpine Fault rupture might not feel as sharp as the February 2011 earthquake, Bradley said, but it would last a lot longer – about two or three minutes.
It would be more of a rolling motion for people in Christchurch, because of their distance away from the fault, he said.
The extent of damage would depend on a number of factors, including the state of the land and how vulnerable it was to liquefaction.
"If you're living on land that doesn't liquefy, then an Alpine Fault earthquake is unlikely to cause damage to your home in Christchurch," he said.
Other problems were more likely to be an issue, such as damage to underground pipes, and major landslides along the South Island's main highways.
Bradley said emergency resources would be stretched if a major earthquake struck, and people could expect to "feel far more alone".
He stressed the importance of being prepared, as main roading routes between Canterbury and the West Coast could be cut off.
"There are things we can do about that . . . by removing some of the really susceptible parts [of the hills]," he said.
"Now that we have that understanding, we can prepare for it better, and hopefully we can lessen the impact it has on us as a society."
He hoped public pressure on the Government would result in action.
ARE YOU PREPARED?
Civil Defence recommends preparing essential emergency items, including:
- Torch with spare batteries or a self-charging torch
- Radio with spare batteries
- Wind and waterproof clothing, sun hats, and strong outdoor shoes.
- First aid kit and essential medicines
- Blankets or sleeping bags
- Pet supplies
- Toilet paper and large rubbish bags for your emergency toilet
- Face and dust masks
- Food and water for at least three days.