No announcement yet.

Saturday's Tonga Volcano Details


  • Saturday's Tonga Volcano Details

    The eruption of the Hunga-Tonga-Hunga-Ha'apai volcano on Saturday was so large, it was a spectacle best appreciated from space.

    The eruption was remarkable in that it involved the simultaneous formation of a volcanic ash plume, an atmospheric shock wave and a series of tsunami waves.
    While details are still emerging and we are still within an eruption episode that could have more twists and turns, there are several pieces of information that can help us begin to understand this event and why it occurred.

    Story By Shane Cronin /

    M 5.8 Volcanic Eruption - 68 km NNW of Nuku‘alofa, Tonga
    2022-01-15 04:14:45 (UTC)20.546°S 175.390°W0.0 km depth

    First, let's look at the eruption. Events of this magnitude occur roughly once a decade around the world, but for this volcano an eruption of this scale is a rarity. Based on my research, using radiocarbon dating to examine the ash and deposits from past eruptions, it seems this latest eruption is a once-in-a-millennium event for the Hunga-Tonga-Hunga-Ha'apai volcano.
    It takes roughly 900-1000 years for the Hunga volcano to fill up with magma, which cools and starts to crystallize, producing large amounts of gas pressure inside the magma. As gases start to build up pressure, the magma becomes unstable. Think of it like putting too many bubbles into a champagne bottle -- eventually, the bottle will break.
    As the magma pressure rises, the cold and wet rock above the magma fails and suddenly releases the pent-up pressure. The eruption we saw on Saturday blasted rock, water, and magma 30 km high into the atmosphere, and was profound in terms of its energy. Within 30 minutes, the resulting cloud seen from space was over 350 km (or 218 miles) in diameter, with ash falling out onto several Tongan islands.
    As for tsunamis, they are most commonly caused by earthquakes. When tectonic plates shift under the ocean, it can displace enough water to cause massive waves. So how does a partially submerged volcano in the southwest Pacific create enough energy to produce tsunami waves that hit the West coast of the US?

    While it's still unclear what exactly caused the tsunami, there are at least two distinct possibilities -- and the first has to do with the expansive force of the initial eruption. On Saturday, the eruption of magma from the volcano created a sudden release of pressure, producing supersonic air pressure waves that could be seen from space.
    These air pressure waves traveled more than 2000 km (1,200 miles) to New Zealand and were felt as far as the United Kingdom and Finland.
    The atmospheric waves and the initial blast affected the ocean surface, causing the giant waves that then hit the Tongan island of Tongatapu and the capital of Nuku'alofa. Early videos showed the waves splashing over roads before the plume of ash darkened the sky.
    Another possible cause of the tsunami waves could have been the remarkable changes within the Hunga volcano. In the aftermath of the eruption, images from satellite radar imagery show the central part of the volcano which previously rose above sea level has since disappeared below the waves. This indicates when the eruption occurred, the sudden loss of magma likely caused the central portion of the volcano to collapse, creating a caldera, or a hollow depression. This collapse could have displaced the water, generating tsunami waves that radiated outwards across the Pacific and all the way to California.

    The Hunga eruption was also astounding in terms of all the lightning generated. This is caused by the electrostatic interaction of very fine volcanic "ash" particles in the air. Weather satellites and lightning researchers are calling this one of the most significant events they have ever seen, with lightning strikes peaking at 63,000 events per 15 minutes.
    Past eruptions from this volcano -- such as the 2014 eruption that created a new island -- included many phases of eruption, and thus we could see more explosions in the coming days and weeks. One moderating factor is the caldera is now underwater, making it harder for eruptions to break through into the atmosphere.
    This could mean a shift to more submarine-style explosive eruptions. While this would mean a smaller atmospheric impact, there could still be an elevated risk of tsunamis, and people who live in coastal areas around the Pacific should be on high alert in the coming weeks.
    Even though our past research has highlighted the importance of the power of eruptions at this volcano, predicting volcanic eruptions to the day and hour remains impossible. This is particularly difficult at a volcano so far offshore, with no power and a shifting, dynamic environment. The only observations are possible via satellite methods, which give a few minutes warning at best for the local residents of Tonga.

    They say every major eruption brings with it a new surprise. This event has shown us clearly volcanoes can be very effective at generating tsunami events, and while Tonga is a long way away from most other countries, its volcanoes can threaten low-lying areas of nations around the globe.
    Over the next days to weeks, we will learn more about this fascinating and dangerous volcano and also the hazards of submarine calderas. Early reports suggest Tonga has experienced significant damage due to tsunami, with many outlying areas still out of reach. We can only hope at the moment everyone in Tonga is safe and well.

    Santa Cruz Small Craft Harbor images © Mike Evans

      Posting comments is disabled.

    Latest Articles


    • OBR's : Bringing The Goods Home!
      by Photoboy

      In part five of this series, IMOCA and The Ocean Race shine a spotlight on the OBRs (On-Board Reporters) who are responsible for taking photos, filming videos and writing texts in seemingly impossible conditions, to give the outside world an insight into life on board.

      Though their presence aboard each boat has been compulsory for the past 10 years or so, we discover that several sailors have actually combined the post of crew and reporter since the first editi...
      05-27-2022, 11:19 AM
    • The Ups And Downs Of Lake Garda Foil GC 32 Riva Cup
      by Photoboy
      Tentative early lead for Zoulou at the GC32 Riva Cup

      Lake Garda was playing awkward for today’s opening rounds of the GC32 Riva Cup, first event of the 2022 GC32 Racing Tour. To the south of Riva del Garda, the racing was delayed only slightly but this allowed the lake’s southerly Ora wind to build to 16-18 knots. Reaching starts in this amount of wind enabled the nimble one design foiling catamarans to set off across the start line and converge on the
      05-26-2022, 02:43 PM
    • Consistency Puts Quantum Atop Leaderboard
      by Photoboy
      Quantum Racing Take Charge In Baiona

      Lighter winds prevailed on Galicia’s beautiful Ria de Vigo as the third day of racing at the ABANCA 52 SUPER SERIES Baiona Sailing Week produced two different race winners and saw Quantum Racing step clear at the top of the leaderboard.

      While Tony Langley’s British flagged Gladiator team, with Paul Goodison on tactics, read the first beat of the first race best – tacking off the signal boat right end of
      05-26-2022, 12:57 PM
    • Aiming For Gender Equity In Ocean Race
      by Photoboy
      The Ocean Race aims for equal number of male and female sailors in the event by 2030

      Viva Mexico in The Ocean Race Europe
      ? Jen Edney/Viva Mexico/The Ocean Race

      The ambitious target is part of Horizon, a new collaboration with The Magenta Project, World Sailing Trust and PA Consulting, dedicated to increasing the number of women in professional sailing. The group is calling on the sailing, marine and sports industries to join
      05-26-2022, 08:27 AM
    • The Plattners Remain Atop The Heap
      by Photoboy
      Quantum Racing On The Prowl But Phoenix Go Four Points Clear in Galicia

      While Quantum Racing made the best of the great conditions on Galicia’s Ri'a de Vigo on the second day of the ABANCA 52 SUPER SERIES Baiona Sailing Week scoring a first and a second it is Phoenix which has stretched their overall regatta lead to four clear points.
      Quantum Racing won the first race of the day which was contested in 15-18kts of breeze whilst Phoenix followed up their
      05-25-2022, 11:56 AM
    • Galicia Opens The Door For 2022 Super Series Season
      by Photoboy

      The 52 SUPER SERIES fleet warmed up for Tuesday’s start of the 2022 season with three good practice races today on the beautiful r?a de Vigo off Baiona where the world’s leading grand prix monohull circuit is visiting for the very first time in its ten year history.
      As if to underline how open this five-regatta season is likely to be, there were three different race winners, Harm M?ller Spreer’s Platoon, the Plattner family’s Phoenix with Tom Slingsby
      05-23-2022, 12:12 PM