NZ Herald
  • Home
  • Latest news
  • Herald NOW
  • Video
  • New Zealand
  • Sport
  • World
  • Business
  • Entertainment
  • Podcasts
  • Quizzes
  • Opinion
  • Lifestyle
  • Travel
  • Viva
  • Weather

Subscriptions

  • Herald Premium
  • Viva Premium
  • The Listener
  • BusinessDesk

Sections

  • Latest news
  • New Zealand
    • All New Zealand
    • Crime
    • Politics
    • Education
    • Open Justice
    • Scam Update
  • Herald NOW
  • On The Up
  • World
    • All World
    • Australia
    • Asia
    • UK
    • United States
    • Middle East
    • Europe
    • Pacific
  • Business
    • All Business
    • MarketsSharesCurrencyCommoditiesStock TakesCrypto
    • Markets with Madison
    • Media Insider
    • Business analysis
    • Personal financeKiwiSaverInterest ratesTaxInvestment
    • EconomyInflationGDPOfficial cash rateEmployment
    • Small business
    • Business reportsMood of the BoardroomProject AucklandSustainable business and financeCapital markets reportAgribusiness reportInfrastructure reportDynamic business
    • Deloitte Top 200 Awards
    • CompaniesAged CareAgribusinessAirlinesBanking and financeConstructionEnergyFreight and logisticsHealthcareManufacturingMedia and MarketingRetailTelecommunicationsTourism
  • Opinion
    • All Opinion
    • Analysis
    • Editorials
    • Business analysis
    • Premium opinion
    • Letters to the editor
  • Politics
  • Sport
    • All Sport
    • OlympicsParalympics
    • RugbySuper RugbyNPCAll BlacksBlack FernsRugby sevensSchool rugby
    • CricketBlack CapsWhite Ferns
    • Racing
    • NetballSilver Ferns
    • LeagueWarriorsNRL
    • FootballWellington PhoenixAuckland FCAll WhitesFootball FernsEnglish Premier League
    • GolfNZ Open
    • MotorsportFormula 1
    • Boxing
    • UFC
    • BasketballNBABreakersTall BlacksTall Ferns
    • Tennis
    • Cycling
    • Athletics
    • SailingAmerica's CupSailGP
    • Rowing
  • Lifestyle
    • All Lifestyle
    • Viva - Food, fashion & beauty
    • Society Insider
    • Royals
    • Sex & relationships
    • Food & drinkRecipesRecipe collectionsRestaurant reviewsRestaurant bookings
    • Health & wellbeing
    • Fashion & beauty
    • Pets & animals
    • The Selection - Shop the trendsShop fashionShop beautyShop entertainmentShop giftsShop home & living
    • Milford's Investing Place
  • Entertainment
    • All Entertainment
    • TV
    • MoviesMovie reviews
    • MusicMusic reviews
    • BooksBook reviews
    • Culture
    • ReviewsBook reviewsMovie reviewsMusic reviewsRestaurant reviews
  • Travel
    • All Travel
    • News
    • New ZealandNorthlandAucklandWellingtonCanterburyOtago / QueenstownNelson-TasmanBest NZ beaches
    • International travelAustraliaPacific IslandsEuropeUKUSAAfricaAsia
    • Rail holidays
    • Cruise holidays
    • Ski holidays
    • Luxury travel
    • Adventure travel
  • Kāhu Māori news
  • Environment
    • All Environment
    • Our Green Future
  • Talanoa Pacific news
  • Property
    • All Property
    • Property Insider
    • Interest rates tracker
    • Residential property listings
    • Commercial property listings
  • Health
  • Technology
    • All Technology
    • AI
    • Social media
  • Rural
    • All Rural
    • Dairy farming
    • Sheep & beef farming
    • Horticulture
    • Animal health
    • Rural business
    • Rural life
    • Rural technology
    • Opinion
    • Audio & podcasts
  • Weather forecasts
    • All Weather forecasts
    • Kaitaia
    • Whangārei
    • Dargaville
    • Auckland
    • Thames
    • Tauranga
    • Hamilton
    • Whakatāne
    • Rotorua
    • Tokoroa
    • Te Kuiti
    • Taumaranui
    • Taupō
    • Gisborne
    • New Plymouth
    • Napier
    • Hastings
    • Dannevirke
    • Whanganui
    • Palmerston North
    • Levin
    • Paraparaumu
    • Masterton
    • Wellington
    • Motueka
    • Nelson
    • Blenheim
    • Westport
    • Reefton
    • Kaikōura
    • Greymouth
    • Hokitika
    • Christchurch
    • Ashburton
    • Timaru
    • Wānaka
    • Oamaru
    • Queenstown
    • Dunedin
    • Gore
    • Invercargill
  • Meet the journalists
  • Promotions & competitions
  • OneRoof property listings
  • Driven car news

Puzzles & Quizzes

  • Puzzles
    • All Puzzles
    • Sudoku
    • Code Cracker
    • Crosswords
    • Cryptic crossword
    • Wordsearch
  • Quizzes
    • All Quizzes
    • Morning quiz
    • Afternoon quiz
    • Sports quiz

Regions

  • Northland
    • All Northland
    • Far North
    • Kaitaia
    • Kerikeri
    • Kaikohe
    • Bay of Islands
    • Whangarei
    • Dargaville
    • Kaipara
    • Mangawhai
  • Auckland
  • Waikato
    • All Waikato
    • Hamilton
    • Coromandel & Hauraki
    • Matamata & Piako
    • Cambridge
    • Te Awamutu
    • Tokoroa & South Waikato
    • Taupō & Tūrangi
  • Bay of Plenty
    • All Bay of Plenty
    • Katikati
    • Tauranga
    • Mount Maunganui
    • Pāpāmoa
    • Te Puke
    • Whakatāne
  • Rotorua
  • Hawke's Bay
    • All Hawke's Bay
    • Napier
    • Hastings
    • Havelock North
    • Central Hawke's Bay
    • Wairoa
  • Taranaki
    • All Taranaki
    • Stratford
    • New Plymouth
    • Hāwera
  • Manawatū - Whanganui
    • All Manawatū - Whanganui
    • Whanganui
    • Palmerston North
    • Manawatū
    • Tararua
    • Horowhenua
  • Wellington
    • All Wellington
    • Kapiti
    • Wairarapa
    • Upper Hutt
    • Lower Hutt
  • Nelson & Tasman
    • All Nelson & Tasman
    • Motueka
    • Nelson
    • Tasman
  • Marlborough
  • West Coast
  • Canterbury
    • All Canterbury
    • Kaikōura
    • Christchurch
    • Ashburton
    • Timaru
  • Otago
    • All Otago
    • Oamaru
    • Dunedin
    • Balclutha
    • Alexandra
    • Queenstown
    • Wanaka
  • Southland
    • All Southland
    • Invercargill
    • Gore
    • Stewart Island
  • Gisborne

Media

  • Video
    • All Video
    • NZ news video
    • Herald NOW
    • Business news video
    • Politics news video
    • Sport video
    • World news video
    • Lifestyle video
    • Entertainment video
    • Travel video
    • Markets with Madison
    • Kea Kids news
  • Podcasts
    • All Podcasts
    • The Front Page
    • On the Tiles
    • Ask me Anything
    • The Little Things
  • Cartoons
  • Photo galleries
  • Today's Paper - E-editions
  • Photo sales
  • Classifieds

NZME Network

  • Advertise with NZME
  • OneRoof
  • Driven Car Guide
  • BusinessDesk
  • Newstalk ZB
  • Sunlive
  • ZM
  • The Hits
  • Coast
  • Radio Hauraki
  • The Alternative Commentary Collective
  • Gold
  • Flava
  • iHeart Radio
  • Hokonui
  • Radio Wanaka
  • iHeartCountry New Zealand
  • Restaurant Hub
  • NZME Events

SubscribeSign In
Advertisement
Advertise with NZME.
Home / New Zealand

The Conversation: New Zealand sits on top of the remains of a giant ancient volcanic plume

Other
27 May, 2020 11:07 PM5 mins to read

Subscribe to listen

Access to Herald Premium articles require a Premium subscription. Subscribe now to listen.
Already a subscriber?  Sign in here

Listening to articles is free for open-access content—explore other articles or learn more about text-to-speech.
‌
Save

    Share this article

New Zealand sits upon the remains of a super volcano. Photo / 123RF

New Zealand sits upon the remains of a super volcano. Photo / 123RF

Opinion

Back in the 1970s, scientists came up with a revolutionary idea about how Earth's deep interior works. They proposed it is slowly churning like a lava lamp, with buoyant blobs rising as plumes of hot mantle rock from near Earth's core, where rocks are so hot they move like a fluid.

According to the theory, as these plumes approach the surface they begin to melt, triggering massive volcanic eruptions. But evidence for the existence of such plumes proved elusive and geologists had all but rejected the idea.

Read more: The Conversation: 'Don't sacrifice health for the economy', say Aussie experts
The Conversation: The perils of perfectionism during lockdown
The Conversation: Five ways to help stop misinformation about Covid-19 coronavirus

Yet in a paper published today, evidence can now be provided. The results show that New Zealand sits atop the remains of such an ancient giant volcanic plume and show how this process causes volcanic activity and plays a key role in the workings of the planet.

Unusual vibrations

Advertisement
Advertise with NZME.
Advertisement
Advertise with NZME.

About 120 million years ago - during the time of dinosaurs in the Cretaceous period - vast volcanic eruptions under the ocean created an underwater plateau about the size of India. Over time, it was broken up by the movements of tectonic plates. One fragment now lies beneath New Zealand and forms the Hikurangi Plateau.

We measured the speed of seismic pressure waves - effectively soundwaves - and how they travel through mantle rocks beneath the Hikurangi Plateau. These vibrations were triggered either by earthquakes or deliberate explosions and reached speeds of 9 kilometres per second.

It's well known these waves, known as P-waves, travel in the uppermost mantle of the Earth at a remarkably constant speed: around 8.1km per second (about 30,000km per hour). Even small deviations from this constant speed reveal important information about the state of the mantle rocks.

Advertisement
Advertise with NZME.

Since the late 1970s, fast P-wave speeds (8.7-9.0km/s) had been reported from a depth of about 30km under New Zealand's eastern North Island. The seismic vibrations recorded in these early data were only travelling in one direction through a small part of the mantle, and the significance of the high speed was unclear.

Our new data is much more extensive, from a major seismic experiment in 2012 that spanned the southern North Island and offshore regions, including the Hikurangi Plateau.

It shows the speed of P-waves reached 9km/s, regardless of the horizontal direction in which they travelled. But a careful analysis of vibrations triggered by deep earthquakes showed unusually low speeds for vibrations travelling in the vertical direction.

This reveals crucial information about how the mantle rocks have been stretched or squeezed by the huge forces inside the Earth, and this turns out to confirm the existence of the elusive plumes.

Discover more

Opinion

Should the Pacific be included in New Zealand's travel bubble?

07 Jun 11:39 PM
New Zealand

Bomb squad called out over chemical incident at university

25 Jun 03:29 AM

A seismic pancake

The pattern of seismic speeds observed requires the mantle rocks beneath the Hikurangi Plateau to have been stretched and squeezed in much the same way as one might produce a pancake shape by flattening a rubber ball.

When computer simulations of rising plumes in the mantle were carried out, they reproduced exactly this pancake flattening pattern, as the mushroom-shaped head of the plume spreads sideways and collapses near the surface.

Data from seismic experiments by international teams on other oceanic plateaux in the south-west Pacific region was also studied. Remarkably, both the Manihiki and Ontong-Java plateaux showed the same pattern as that observed beneath the Hikurangi Plateau. P-waves travelled at the same high speeds regardless of the horizontal direction, but at significantly slower speeds in the vertical direction.

Reconstructing an ancient superplume

The major oceanic plateaux of the southwest Pacific are now dispersed, but we know how they once fitted together, about 120 million years ago. They formed a region underlain by a thick layer of volcanic rock, thousands of kilometres across.

Advertisement
Advertise with NZME.

Analysis shows this entire region lay above the single head of a giant plume – a superplume – which melted to produce massive lava outbursts over a geologically brief period of a few million years.

Siberia is the only other place on Earth where this pattern of P-wave speeds has been observed in the upper mantle. And it turns out this was also the scene of widespread volcanic eruptions about 250 million years ago, thought to be caused by the rise of a superplume.

This volcanic activity may have changed Earth's climate and triggered a mass extinction that affected the evolution of life.

New Zealand and some scattered islands in the southwest Pacific are perched on the remains of what was once an immensely powerful geological force. We don't know whether this process is still ongoing today, but new seismic techniques for finding these superplume remnants may help us discover more - providing further insight into the many connections between the deep interior of our planet and what happens at the surface.

Simon Lamb
Associate Professor in Geophysics, Te Herenga Waka — Victoria University of Wellington

Timothy Stern
Professor of Geophysics, Te Herenga Waka — Victoria University of Wellington

Advertisement
Advertise with NZME.

Disclosure statement: Simon Lamb receives funding from New Zealand Marsden Fund, New Zealand Earthquake Commission, Victoria University of Wellington University Research Fund. Timothy Stern receives funding from. New Zealand Marsden Fund, NZ Earthquake Commission, NZ Royal Society Endeavour Fund.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Save

    Share this article

Latest from New Zealand

Premium
New Zealand

Richter scales and fishy tales: When a small earthquake spoiled a day of fishing

17 Jun 06:00 PM
New Zealand

'Restricted is a lot more intense': Students back overhaul of full driver licence test

17 Jun 06:00 PM
Premium
New Zealand

'Feeding kittens': Debate on supporting Rotorua's rough sleepers heats up

17 Jun 06:00 PM

Jono and Ben brew up a tea-fuelled adventure in Sri Lanka

sponsored
Advertisement
Advertise with NZME.

Latest from New Zealand

Premium
Richter scales and fishy tales: When a small earthquake spoiled a day of fishing

Richter scales and fishy tales: When a small earthquake spoiled a day of fishing

17 Jun 06:00 PM

Everyone struggled for bites after Monday morning's quake. So were the fish spooked by it?

'Restricted is a lot more intense': Students back overhaul of full driver licence test

'Restricted is a lot more intense': Students back overhaul of full driver licence test

17 Jun 06:00 PM
Premium
'Feeding kittens': Debate on supporting Rotorua's rough sleepers heats up

'Feeding kittens': Debate on supporting Rotorua's rough sleepers heats up

17 Jun 06:00 PM
Premium
Simon Wilson: Chlöe Swarbrick's lost Monopoly lessons

Simon Wilson: Chlöe Swarbrick's lost Monopoly lessons

17 Jun 05:00 PM
Help for those helping hardest-hit
sponsored

Help for those helping hardest-hit

NZ Herald
  • About NZ Herald
  • Meet the journalists
  • Newsletters
  • Classifieds
  • Help & support
  • Contact us
  • House rules
  • Privacy Policy
  • Terms of use
  • Competition terms & conditions
  • Our use of AI
Subscriber Services
  • NZ Herald e-editions
  • Daily puzzles & quizzes
  • Manage your digital subscription
  • Manage your print subscription
  • Subscribe to the NZ Herald newspaper
  • Subscribe to Herald Premium
  • Gift a subscription
  • Subscriber FAQs
  • Subscription terms & conditions
  • Promotions and subscriber benefits
NZME Network
  • The New Zealand Herald
  • The Northland Age
  • The Northern Advocate
  • Waikato Herald
  • Bay of Plenty Times
  • Rotorua Daily Post
  • Hawke's Bay Today
  • Whanganui Chronicle
  • Viva
  • NZ Listener
  • Newstalk ZB
  • BusinessDesk
  • OneRoof
  • Driven Car Guide
  • iHeart Radio
  • Restaurant Hub
NZME
  • About NZME
  • NZME careers
  • Advertise with NZME
  • Digital self-service advertising
  • Book your classified ad
  • Photo sales
  • NZME Events
  • © Copyright 2025 NZME Publishing Limited
TOP