News | Environment
1 Aug 2025 11:24
NZCity News
NZCity CalculatorReturn to NZCity

  • Start Page
  • Personalise
  • Sport
  • Weather
  • Finance
  • Shopping
  • Jobs
  • Horoscopes
  • Lotto Results
  • Photo Gallery
  • Site Gallery
  • TVNow
  • Dating
  • SearchNZ
  • NZSearch
  • Crime.co.nz
  • RugbyLeague
  • Make Home
  • About NZCity
  • Contact NZCity
  • Your Privacy
  • Advertising
  • Login
  • Join for Free

  •   Home > News > Environment

    Why Russia's megathrust earthquake was among biggest ever recorded, but damage was minimal

    It was one of the strongest tremors in recorded history, but Wednesday's megathrust earthquake brought less tsunami damage than feared. Here are some factors that may have been at play.



    One of the largest earthquakes in recorded history set off tsunami warnings across the Pacific Ocean on Wednesday. 

    But it has not proved as destructive as experts feared. 

    Here are the factors that contributed to that outcome. 

    How big was Wednesday's earthquake?

    It was among the 10 strongest ever recorded.

    The magnitude-8.8 earthquake was the largest since 2011, when a magnitude-9.1 tremor and subsequent tsunami struck off the coast of Japan and killed more than 15,000 people.

    Wednesday's earthquake, known as the Kamchatka earthquake, is considered a megathrust earthquake — common to each of the planet's largest recorded quakes.

    What is a megathrust earthquake?

    Earth's outer layers are split into 15 slabs known as tectonic plates.

    These plates slowly shift around — moving a few centimetres every year — and often get stuck against each other due to friction.

    When that happens, stress builds up over time until the plates suddenly shift and cause seismic waves that shake the ground.

    Megathrust earthquakes occur when one tectonic plate has been forced underneath another — a phenomenon known as subduction.

    In this case, it was the Pacific plate beneath the North American plate.

    Stephen Hicks, an environmental seismology expert at University College London, said megathrust earthquakes "cause some of the world's largest ruptures and trans-ocean tsunamis".

    How are tsunamis caused?

    Tsunamis occur when earthquakes displace large amounts of ocean water.

    Megathrust quakes often cause tsunamis because the faults they cause tend to come to, or even directly penetrate, the sea floor, Dr Hicks said.

    How much of the sea floor moves influences whether a tsunami is formed, and how big it might become, added Lisa McNeill, a tectonics professor at the University of Southampton.

    "Some fault movements don't move the sea floor much, and so, there is no tsunami," she said.

    In the case of the Kamchatka earthquake, a large slip occurred and generated a tsunami, Dr McNeill added.

    Why wasn't the tsunami as destructive as others?

    Despite the earthquake triggering tsunami warnings across the Pacific Ocean, no deaths were recorded, and minimal structural damage was reported. 

    Maximum wave heights of five metres were observed in Kamchatka yesterday — a tenth of the heights recorded after the Tohoku Earthquake in 2011, which triggered the Fukushima Daiichi nuclear disaster.

    Waves in Hawaii reached a maximum height of about 1.7 metres.  

    Meghan Miller, a professor of seismology at Australian National University, said where earthquakes strike has a major impact on the severity of subsequent tsunamis. 

    "For the tsunami and earthquake that happened in Japan in 2011, the distances [to land] were much closer," she told ABC Radio National Breakfast

    "So the distance for the waves to travel to the coast of Japan was much shorter." 

    Dr McNeill said the height of tsunami waves can also be affected by the shape of the sea floor near the coast.

    "[The waves] are small at sea but travel fast, and it is when they reach shallow water that they build in height again," she said.

    "[A] tsunami can have varied heights on one coastline, and it could generate surprisingly large wave heights."

    She added that wave heights recorded after the Kamchatka earthquake were still "significant", but the potential for destruction was minimised.

    The tremor triggered tsunami warnings across the Pacific Ocean, as far away as Hawaii, Chile, and Ecuador.

    "This has been established in the Pacific since the 1960s, and people therefore receive warnings about the tsunami and can evacuate," she said.

    "It is harder for those living close to the earthquake as they have less time, but the earthquake is their warning of a tsunami and [the] prompt to move to higher ground."

    Many nations with sea borders have government-run programs to detect and monitor threats caused by earthquakes and tsunamis that may impact the region, and are charged with alerting communities of incoming threats and issuing evacuation orders.  

    There were no warning systems in place in the Indian Ocean when the 2004 Boxing Day tsunami occurred.

    The enormity of the natural disaster's death toll, estimated to be about 225,000, is attributed to the lack of evacuation alerts.


    ABC




    © 2025 ABC Australian Broadcasting Corporation. All rights reserved

     Other Environment News
     31 Jul: Just as NZ began collecting meaningful data on rainbow communities, census changes threaten their visibility
     31 Jul: Tsunami threats downgraded across South America and the Pacific after Russian earthquake
     31 Jul: A boil water notice could be shortened for two Central Otago communities
     31 Jul: Kamchatka earthquake is among top 10 strongest ever recorded. Here’s what they have in common
     31 Jul: US government may be abandoning the global climate fight, but new leaders are filling the void – including China
     31 Jul: Japan's citizens calmly swing into action in response to tsunami threat
     30 Jul: Auckland Emergency Management's opening four Civil Defence Centres for residents living on vessels
     Top Stories

    RUGBY RUGBY
    Drawing men's attention back to netball's ANZ Premiership is a core objective from TVNZ after signing a free-to-air broadcast deal with Netball New Zealand for 2026 More...


    BUSINESS BUSINESS
    Kiwibank will have to prove itself before increased capital can result in the desired levels of competition More...



     Today's News

    Entertainment:
    Aaron Phypers has accused Denise Richards of assaulting him 10:53

    Entertainment:
    A Hawaiian epic made in NZ: why Jason Momoa’s Chief of War wasn’t filmed in its star’s homeland 10:36

    National:
    New peace plan increases pressure on Israel and US as momentum grows for Palestinian statehood 10:26

    Entertainment:
    Hulk Hogan felt "weak" and "embarrassed" shortly before he passed away 10:23

    Living & Travel:
    Your dog can read your mind – sort of 10:16

    National:
    Friday essay: libertarian tech titan Peter Thiel helped make JD Vance. The Republican kingmaker’s influence is growing 10:06

    Politics:
    Jewish activists accused of eroding centuries of tradition at Jerusalem's holiest sites 9:06

    Motoring:
    F1 Hungarian Grand Prix: Max Verstappen to stay at Red Bull, Oscar Piastri seeks another Hungaroring win 7:36

    International:
    Border conflict reveals how Cambodia and Thailand have leveled up their weapons of war 7:06

    International:
    Why this image of an emaciated Gazan boy sparked controversy 21:06


     News Search






    Power Search


    © 2025 New Zealand City Ltd