This summer we’re bringing back some of the best-read Premium articles of 2024.Today we take a look at someof thebiggest stories around the science of natural disasters in New Zealand.
This tidal surge rolled into Tokomaru Bay on the North Island's east coast on March 5 after a major earthquake in the Kermadec Islands. New simulations suggesting the quake-making potential of the vast Hikurangi-Kermadec subduction zone isn’t quite as high as was first feared.
Surprise findings have changed what scientists have long assumed about New Zealand’s major tsunami threat from the north.
And for once, the news isn’t so bad, with updated simulations suggesting the quake-making potential of the vast Hikurangi-Kermadec subduction zone is somewhat lower than they’ve long feared.
Around the world, subduction zones have been responsible for some of the planet’s biggest cataclysms: most recently the devastating 2004 Sumatra and 2011 Tōhoku “megathrust” earthquakes and tsunamis.
But much has been unclear to scientists about the worst that might be unleashed from the sprawling margin stretching thousands of kilometres above the New Zealand’s northeast, where the Australian and Pacific plates collide.
Some of the biggest events in the zone have struck around Raoul Island, the largest and northernmost of the main Kermadec Islands.
That included a huge magnitude-8.2 quake in January 1976 and an 8.1 event in March 2021 – both of which hit shortly after slightly smaller ones.
Large as those big quakes were – the latter sparked widespread warnings and evacuations in New Zealand and the Pacific – earlier models have suggested the very biggest in the region might be able to reach 9.5, equivalent to that recorded near Chile in 1960.
Google's Android app, based on phone data rather than GeoNet sensors, is the closest thing Kiwis have to a personally-accessible earthquake early warning system - but it's caused confusion in previous events here.
“A bit of a rumble... then boom,” said one Lower Hutt resident.
“Lots of noise - and rock ‘n’ roll,” said another person 200km away in Whanganui.
It wasn’t the day’s 5.7 quake they were describing - but one that hit in the same region on September 22, 2022, and which some 45,000 people from Invercargill to Kaitaia reported feeling.
Aside from forcing flights away from Wellington, it wasn’t unlike many of the two-dozen-or-so other quakes of that scale which rock our shaky isles in a given year without causing major damage.
But for scientists, the event yielded a trove of valuable data that’s taken us a small step closer to answering a long-standing question: can we warn people before the big one hits?
Auckland lies sprawled across a young and potentially active volcanic field.
Auckland’s next major volcanic eruption could throw concentrated sulphur dioxide across hundreds of square kilometres – threatening the health of the city.
That’s according to a new study simulating the impact volcanic gases could cause in an extreme eruption scenario.
While its 53 volcanoes are considered unlikely to erupt again, the Auckland Volcanic Field is young, potentially active, and could produce fast-moving surges of hot rock and gas, lava bombs and widespread ashfall.
Recent research has suggested Auckland will receive between five and 15 days’ warning of an imminent eruption , forcing the evacuation of perhaps more than 400,000 people from their homes.
Until now however, the potential health risk of sulphur dioxide from rising magma has been less understood.
Scientists have taken a closer look at indirect risks from coastal flooding. Photo / Dean Purcell
A first-of-its-kind analysis has revealed a large but previously hidden chunk of the population at risk from flooding – with our most deprived disproportionately endangered.
Modelling suggests some 750,000 people and 500,000 buildings near rivers and beaches are exposed to extreme flooding today, and those figures will only rise as our planet continues to heat.
While estimates like these tell us about who’s at risk of direct impacts, less has been known about indirect ones, like residents being cut off from vital services amid disasters.
A new study offers a first glimpse at this picture – and finds some troubling trends.
The Hikurangi Subduction Zone is where the Pacific plate dives beneath the Australian plate on the east coast of the North Island. Images / East Coast Labs
Ancient traces of massive undersea landslides has transformed scientists’ understanding of our biggest fault zone - and its ability to unleash tsunami-generating mega-quakes off the Hawke’s Bay coast.
The Hikurangi Subduction Zone marks the boundary where the Pacific plate plunges below the Australian plate. If we drained the ocean, it’d appear as a vast mountain range rising up from the sea floor off the North Island’s east coast.
This endless tectonic scrum produces an enormous amount of pent-up energy, and modelling has estimated one-in-four odds of southern part of the zone triggering a magnitude-8.0-plus earthquake within the next 50 years.
In May, scientists warned a major Hikurangi tsunami could kill more than 22,000 and injure nearly 26,000 - even assuming three-quarters of people could evacuate in time.
Now, a just-published study, researchers have shed crucial new light on the poorly understood central part of the zone, located offshore and underneath Hawke’s Bay.
