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Aotearoa New Zealand sits astride tectonic plates, which puts the country at risk of damaging earthquakes and tsunamis.
The Mahurangi region, as part of Te Tai Tokerau, is contributing to a national tsunami response by hosting state of the art equipment that watches the tsunami forming process as it happens, allowing scientists to issue alerts early and protect our coastlines.
GNS Science seismologist Bill Fry says New Zealand is sadly familiar with the extreme damage that earthquakes can cause.
“But what people may not know is that earthquakes are also responsible for around 80% of the world’s damaging tsunami activity,” he says.
Earthquakes are caused from movement along faults within the earth, creating energy in the form of seismic waves, which cause the ground to shake. GNS Science monitors seismic activity as part of its natural hazards and risks management.
Fry says science is continually advancing and new and improved global technology and understanding greatly enhances the capacity to monitor, measure, respond to and mitigate earthquake and tsunami hazard.
Real-time seismic monitoring is undertaken in a variety of ways, all contributing to New Zealand’s science knowledge base and informing national resilience and response activity.
“If we can rapidly characterise earthquake sources, we can better understand if and when a tsunami might be on its way, and New Zealand’s ability to respond to and recover from earthquakes and tsunami will be significantly improved.
“Getting advance warning of earthquakes and tsunamis buys time, and when we deal with tsunamis, every second counts.
“With near real-time, high-accuracy, geographically explicit information, our scientists and New Zealand’s hazard responders can make better decisions.”
There are a raft of ways that GNS Science keeps seismic activity on its 24-hour radar. The GeoNet programme operates hundreds of motion sensors at different sites around NZ. The sensors detect earthquake waves that arrive long before the first tsunami waves, giving scientists the first ‘heads up’ that a big earthquake has occurred.
A deep-ocean assessment and reporting of tsunami (DART) network monitors waves in the deeper ocean around New Zealand and the south-west Pacific, warning experts of potential tsunami threat. A tsunami gauge network comprises 18 sites across the North and South, Raoul and Chatham Islands to support detection and analysis of water volume changes at our coasts.
Exciting new monitoring tools that use this data are being developed through the Rapid Characterisation of Earthquakes and Tsunamis (RCET) project.
RCET uses this data to speed up tsunami early warning capability, allowing coastal communities better opportunity to respond. Timely and accurate tsunami warnings can save lives and reduce economic and societal disruption, Fry says.
“Playing its part in the geohazard defence force, Te Tai Tokerau is helping to protect the people and property of New Zealand and Pacific neighbours from natural harms. With its unique geology and geography, Northland is one of the best places in the whole of the south-west Pacific to watch out for stealth tsunamis – tsunamis that happen without the usual warning signs of long and strong ground shaking.
“Think of being inside and watching a field of sunflowers out the window, blowing in the wind. Just by watching the golden yellow heads of the sunflowers, you can see which way the wind is blowing and how strong it might be.
“It’s the same with our seismometers. They watch for the earthquake signals we can’t otherwise be aware of, giving us the first indication that a stealth tsunami might be heading our way.”
Thanks to the goodwill and support of dozens of local landowners, locations for nine seismometers have been agreed and were in situ by Christmas.
GNS Science is currently considering sites for another six, making up an RCET “array” of 15 units that will be working around the clock, helping to protect not only our local communities but the wider New Zealand coastline and the south-west Pacific.
Information from the local monitoring array, when combined with data that is collected from coastal Australia and the Pacific, allows seismic experts to quickly assess south-west Pacific earthquakes. When considered alongside the ocean observations from the DART network, the result is improved, robust, world-class tsunami early warning capability.
“Ultimately, our home-based RCET array enables GNS Science to inform Aotearoa’s National Emergency Management Agency and civil defence teams about potential threats, so they can issue fast and effective tsunami warnings and save lives.”
In time, GNS expects that the seismometer array will extend down through Auckland and the Coromandel.
“If you happen to be on a farm and come across a seismometer, please leave it alone and let it do its magic uninterrupted. It has a very important job to do!”
Further reading: www.gns.cri.nz/research-projects/rcet/
