Seismic shock for city

A FAULT zone running through Kaikorai Valley has been discovered as scientists work to discover whether an earthquake like the devastating Christchurch quake could happen in Dunedin.

The newly named Kaikorai Fault has been deemed inactive or in a phase of inactivity, and a study of seismic activity in Dunedin concludes there is no change to hazard levels.

It runs northeast along Kaikorai Valley towards Ross Creek.

But the report from GNS Science, the University of Otago and others said it was important to bear in mind that while the likelihood of a rupture of Dunedin faults was low, it was ‘‘no lower than those of faults around Christchurch prior to 2010’’.

Despite that, city leaders said yesterday Dunedin’s emergency management planning was sufficient.

The study, released yesterday, said the Kaikorai Fault ‘‘most likely would rupture together with the Green Island Fault, located offshore’’.

In low to moderate seismic areas, such as the wider Dunedin area, active faults could be dormant for more than 100,000 years.

While the Akatore and Titri faults seemed to be in an active period, the Kaikorai Fault was either inactive or in a phase of inactivity.

Ruptures on faults in the wider Dunedin region could generate quakes of magnitude 7 or higher.

The study also found the Titri Fault came closer to Dunedin city than previously thought.

Study leader Pilar Villamor said she did not think the findings would affect matters like insurance for people living near the fault.

‘‘I don’t think it should, because if you evaluate the Kaikorai Fault, it ruptures too seldom to be of high risk to the city.

‘‘It is important to know those things exist there, and it might be dormant for another 100,000 years, hopefully, but if it suddenly starts having signs of activity, we are aware that it’s a feature there, rather than just totally ignoring it.’’

Otago Regional Council engineering, hazards and science director Gavin Palmer said the study was ‘‘a really useful piece of work’’.

The hazard level had not changed, which meant the programmes in place for seismic events were still appropriate.

The council was doing its own work revising the mapping of faults across Otago.

‘‘It adds to the knowledge, it reinforces the importance of readiness and reduction programmes that are in place,’’ Dr Palmer said.

The new information would not change emergency management protocols, but did reinforce the importance of readiness for seismic activity.

On what Kaikorai Valley people needed to do, Dr Palmer said: ‘‘I don’t think it means people need to be any more prepared than they were previously.’’

Mayor Dave Cull said, in the context of a seismically active country and Dunedin being a low risk area, ‘‘this doesn’t seem to mean any change at all’’.

Dunedin was actively working on its resilience and ability to respond to such crises.

‘‘This doesn’t make it any more urgent, from what I can see.’’

The study said it had only ‘‘scratched the surface’’ of fault activity in Otago and more data and analysis were required.