A newly discovered fault line which is just a 90-minute drive from Auckland is to be examined in a project funded by the Earthquake Commission (EQC) to determine its quake risk.

Based on its 25-kilometre length, scientists say the fault has the potential to generate a 6.7 magnitude earthquake, similar to the 7.2 magnitude Darfield earthquake in 2010 which began the Canterbury earthquake sequence.

Making use of improved aerial mapping tools, experts recently discovered the Te Puninga fault, located near Hamilton on New Zealand’s north island in the Waikato district.

Earthquake geologist Pilar Villamor is heading the research project, which is part of an effort to better understand risk in parts of New Zealand that are traditionally seen as safe from quakes.

Dr Villamor’s team is digging trenches across the fault to expose soil layers displaced in previous earthquakes over the past 20,000 years. Samples from each layer will be dated by experts at the University of Waikato and in Spain.

“This will tell us how often the fault has ruptured, and the magnitude of the quakes it has produced,” she says. “That information in turn will help us to understand the risk of future earthquakes in the area and how to prepare.”

EQC research manager Natalie Balfour says the area has traditionally been considered a low seismicity area, much like the Canterbury region before 2010.

“Research shows us that many of these areas have had large earthquakes in the past, and detailed historic data will help understand what could happen in future,” Dr Balfour says.