Premiums are unlikely to rise after the discovery of another fault line in Wellington, because a high level of risk was already assumed, the Insurance Council of New Zealand (ICNZ) says.

The Aotea fault under Wellington Harbour is about 2km long and likely capable of causing moderate to large earthquakes – about 6.3-7.1 in magnitude.

Researchers say several-dozen other geological faults had already been identified in the region, and the latest discovery falls within existing building code hazard calculations.

“The scientific reassurances that the Aotea fault doesn’t dramatically increase Wellington’s earthquake risk… will mean it’s unlikely there will be an impact on insurance premiums,” ICNZ CEO Tim Grafton said.

Scientists from New Zealand’s National Institute of Water and Atmospheric Research (NIWA) mapped the fault during research by GNS Science into the likelihood of large earthquakes in the capital.

“Knowing more about Wellington’s geological faults has major benefits in terms of being better prepared and making the city more resilient to earthquakes,” NIWA Marine Geologist Scott Nodder said.

“It is important to work out its exact location and ground rupture size so this can be incorporated into land use and engineering strategies to mitigate this hazard.”