Major Volcanic eruption, shock waves and tsunami strikes NZ

Updated: May 16

Tonga volcano summary


Hunga Tonga–Hunga Haʻapai is a volcanic island located about 30 km south-southeast of Fonuafoʻou island in Tonga. The volcano is part of the highly active Tonga–Kermadec Islands volcanic arc, a subduction zone extending from New Zealand north-northeast to Fiji.


Sequence of events leading up and beyond the 15th January major eruption.


  • 20th December - Initial large eruption. Volcanic Ash Advisory Centre in Wellington send notice to airlines. Eruption ceased on 21st December.



  • 25th December – unrest continued with satellite imagery showing the Island had grown.

  • 11th January – unrest ceased; Volcanic eruption declared dormant.

  • 14th January - New large eruption, with the plume reaching the Stratosphere and tsunami warnings issued around the Tonga Kingdom. 30cm waves were observed.



  • 15th January – Major eruption around 5:14pm NZT.




Registering a magnitude 5.8 earthquake.

The major eruption generated multiple 1 metre + tsunamis waves across the Pacific.


The pressure shock wave travelling around the planet.



Multiple sonic booms were heard across the New Zealand between 7pm & 11pm. The pressure wave seen on our dramatic barometric air pressure change just after 7pm NZT. The shock wave was travelling at around 1,200 km/h.


Barometric air pressure change

Seismometer recordings

The first tsunami waves began to arrive across the upper North Island around 8:30pm, initial small around 10cm to 20cm in height at Great Barrier Island.


The waves continued and increased in size within 2 hours to reach 86cm between 10:16pm & 10:19pm.


  • 16th January. After midnight the largest waves arrived. The largest being 1.33m between 1:05am and 1:10am.


These waves bought damage to vessels.


Tutukaka marina credit Tim Alexander
Tutukaka marina credit Tim Alexander
Tutukaka marina credit Michael Howard

As of 11:30am today (16th January), small waves are still arriving and the eruption is ongoing. Unfortunately, major volcanic eruptions can be ongoing for extended periods of time and this volcanic caldera may have more in store. More to come.....


Update 23rd January


It's been 8 days since the major eruption and the volcanoes caldera has been calm for the last 6 days above the ocean. Below the caldera and surrounding area, high levels of seismicity and volcanism still exist with 34 Magnitude 4.5+ earthquakes occurring since the major eruption, including 3 under the caldera.



Update 1st February


USGS has now recorded 62 magnitude 4.5+ earthquakes within 70km of the #HungaTongaHungaHaapai caldera since the major eruption, including 2 earthquakes today. Elevated seismicity and volcanism continues under the ocean.



Update 17th February


USGS has now recorded 91 magnitude 4.5+ earthquakes within 70km of the #HungaTongaHungaHaapai caldera since the major eruption, including a M 5.0 overnight near the Caldera. Elevated seismicity and volcanism continues under the ocean.



Update 26th March


It’s been just over 2 months since Tonga’s major volcanic eruption. While volcanism and seismicity have subsided, record high levels of water vapour have continued to spread across earth’s stratosphere according to the latest NASA charts.



The charting of water vapour in the stratosphere by NASA commenced in 2004, so there is only a 17-year comparison to be made. It's quite clear though, that the eruption has drastically increased the content of moisture in the stratosphere since 15th January. It's still too early to know what the impacts are on weather, and climate on earth below, but this chart would indicate that the stratosphere has become warmer since the eruption. As air temperatures rise, warmer air can hold more water vapor increasing the saturation point. Colder air means less water vapor. Normally a warmer stratosphere means a cooler troposphere near earth. Since the eruption. the earth's lower atmosphere has dropped by 0.2c.


We’ll continue monitor the Hunga Tonga Hunga Ha-apai eruption’s impact on the atmosphere over the coming weeks and months. Stay tuned.



Update 16th May - 4 months on


Seismicity and volcanism have abated around Tonga’s undersea volcano but the volcanic eruption on 15th January has disrupted and changed the chemistry of the planet’s stratosphere. Abnormal levels of moisture were injected into the upper Stratosphere and Mesosphere in mid-January and continue to spread across the globe according to NASA’s latest observations.





What does it mean? While there as scientific hypothesis’s, no one knows for sure at this point. An event of this power and size has never been technically observed before due to short term stratospheric moisture records (NASA only since 2004). The eruption reached 58km into the atmosphere is likely to be the most explosive event on earth since 1815’s Mt Tambora volcanic eruption. A 20th century explosive comparison is 1991’s Mt Pinatubo eruption which reached around 40km into the atmosphere. Mt Pinatubo dropped the earth’s temperature from mid-1991 to 1994.


Stay tuned for more over the coming months as the atmospheric event continues to unfold.







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