A fault which runs from Garston to Lake Wānaka has the potential to create a magnitude seven earthquake, new research commissioned by the Earthquake Commission (EQC) has found.

Seismic research on the 100km-long Nevis Fault confirms that the low-seismicity area (one with infrequent earthquakes) has had at least two major ruptures in the past and it has the potential to create an earthquake as significant as the magnitude 7.1 which hit Darfield, Canterbury, 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.

University of Otago lead researcher Mark Stirling says he hopes Southerners are well-prepared for an earthquake. PHOTO: EQC

The faults in Otago and Southland generally have long time periods between earthquakes and they can show great variability in behaviour through time, Mark said.

“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.”

Mark, along with postdoctoral scholar Dr Jack Williams and a team of students and colleagues, returned this week from digging two 25-metre long trenches high in the Upper Nevis Basin (south of Queenstown) to gain a better understanding of the Nevis Fault, and the greater Nevis-Cardrona fault system.

A lot more data would be needed to forecast the timing of the next event with any degree of confidence, he said.

EQC research manager Natalie Balfour said EQC commissioned the work because the Queenstown Lakes District is one of the fastest growing areas in New Zealand, with a huge amount of 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,” Natalie said.

Awareness of earthquake hazard is often not as pronounced in low seismicity areas as in high seismicity areas, and that this could really intensify the impact of a future event, Mark said.

Mark said he hopes knowledge and awareness of local seismic hazards will help Southerners be prepared for an earthquake.

Emergency Management Otago recommends the following steps to be prepared for an earthquake:

● Practice ‘Drop, Cover and Hold’ regularly - it stops you being knocked over, makes you a smaller target for falling and flying objects and protects your head, neck and vital organs. 

● Make a plan to get home, work and community ready so that wherever you might be, you’re prepared and talk about it with your loved ones so that everyone knows what to do. Click https://www.otagocdem.govt.nz/.  

● Create or update your emergency kit today with supplies to last you at least seven days. You can either make your own or buy a kit and add your own items to it. LINK https://www.otagocdem.govt.nz/get-home-ready. 

● Make your home safer by ensuring objects that could fall and hurt people are either relocated or fixed/fastened to the wall or floor. Click https://www.eqc.govt.nz/be-prepared 

● Sign up to Otago Gets Ready for text/email alerts (this is one of Civil Defence’s tools to provide advice for emergency situations that affect you personally including floods, fires etc). It also gives you the opportunity to list any skills, resources or vulnerabilities which helps Civil Defence to plan and get help more quickly to where it’s needed most. 

● There’s a lot more information on earthquakes and how to prepare here. Click https://www.otagocdem.govt.nz/hazards/earthquakes  

Republished by arrangement

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