Hundreds would die in $20b Wgtn quake

18:47, Jun 13 2012
Wellington Earthquake
The coloured bars show the numbers of buildings per square km expected to suffer irreparable damage in a 7.6 quake. The range shown in this projection is between 0 and 60 buildings.

A magnitude 7.6 earthquake striking Wellington during the day could kill hundreds of people, destroy 600 buildings and cost nearly $20 billion to clean up, new research predicts.

The devastating projections are revealed by new disaster prediction software, which scientists are using to simulate the likely fallout from catastrophic natural disasters. It is hoped the RiskScape software will soon provide accurate projections for other disaster events, such as landslides, windstorms and tsunamis to help emergency response agencies prepare for the real thing.

"We all know we live on a major fault, but this modelling helps us understand how a worst case scenario could affect our city," GNS social scientist Kim Wright said.

If "the big one" hit, fracturing Wellington's main active fault, the modelling showed hundreds would be killed, hundreds more seriously injured and 29,000 displaced in the immediate aftermath of a big earthquake.

The number of collapsed and severely damaged buildings would be worst in the densely populated central city and the eastern suburbs.

The 80km Wellington-Hutt Fault starts in Cook Strait and runs through Karori and the central city. The fault is thought to be prone to periodic rupturing based on geological research.


Research from 2010 shows this southern stretch of the larger Wellington Fault – which extends to the Bay of Plenty – ruptures to magnitude 7 or above about every 900 years and last reached that intensity about 300 years ago.

The model was calculated using RiskScape software being developed by GNS Science and the National Institute for Water and Atmospheric Research.

Wright stressed the RiskScape modelling was not yet fully fine-tuned – especially with casualty forecasts. She also warned against thinking of the software as only useful in a worst-case scenario.

"RiskScape is not just about worst case scenarios – it's about understanding all kinds of risks and how we can reduce their impact."

The software could help scientists, asset managers and risk forecasters better understand natural hazards before disaster struck, so planners and agencies, such as Civil Defence, power companies and councils, could try to stem the fallout for people and the economy, she said.

It would eventually be distributed free to disaster response and other not-for-profit agencies.

RiskScape tests for a host of hazards including earthquakes, river flooding, tsunami, volcanic ashfall and windstorms, and calculates replacement costs, casualties, economic losses, disruption to infrastructure and business, and number of people affected.

It is also being tweaked for use in forecasting landslides, coastal storm-tide inundation, volcanic lahars, snowstorms and climate change effects.

Potentially the software could become the industry standard for hazard and impact assessment and it was hoped it would grow "organically" once other agencies started plugging in their own disaster mapping data, she said.

Regional and local councils in the quake-stricken Canterbury area, plus the West Coast and Hawke's Bay have been partners in the project.

Fairfax Media