New Zealand research near Queenstown has confirmed the low seismicity western Otago area has the potential to create an earthquake similar in size to the powerful Darfield Canterbury event in 2010.

“People in Otago and Southland usually only think about the Alpine Fault when they think about earthquakes, but we now know that there are major faults in low-seismicity areas that could produce a major event,” University of Otago lead researcher Mark Stirling said.

Earthquake Commission (EQC) Research Manager Natalie Balfour says the Queenstown Lakes District is one of the fastest growing areas in New Zealand, with new housing and infrastructure development.

“EQC supports this type of research because it is important for developers, local councils, and the public to understand and manage potential seismic hazards,” Ms Balfour said.

Professor Stirling, Postdoctoral Scholar Jack Williams and a team of students and colleagues last week returned from digging two 25-metre-long trenches in the Upper Nevis Basin, south of Queenstown, to gain a better understanding of the Nevis Fault, and greater Nevis-Cardrona fault system.

The combined fault system stretches about 100km from Lake Wanaka to near Garston in Southland, and has the potential to produce an earthquake well into the magnitude 7 range. The new research has found evidence of at least two major prehistorical events.

“We found evidence of the sediment layers being broken up, warped and thrust over each other, which would have been produced by significant seismic events,” Professor Stirling says.

Researchers say there’s not enough information to create probability models to forecast the likelihood of future events, and Otago and Southland region faults generally have long time periods between earthquakes and can show great variability in behaviour.

“But if the Nevis-Cardrona system were to rupture, we’d most definitely see a large earthquake and most of Otago and Southland would feel it,” Professor Stirling said.