The last Tonga eruption caused a 90 meters tsunami, say researchers
(Japan Meteorological Agency/NASA SPoRT / Wikimedia Commons https://bit.ly/3KNJJdu)
The eruption of the Hunga-Tonga-Hunga-Haapai volcano on January of 15 this year caused a tsunami of 90 meters.
An international team of researchers arrived at that conclusion after analyzing changes in atmospheric pressure and sea level and creating nine volcanogenic tsunami models.
The underwater volcano Hunga-Tonga-Hunga-Haapai is located in the South Pacific Ocean.
It belongs to the Tonga-Kermadec island arc, which was formed as a result of the subsidence of the Pacific plate under the Indo-Australian plate.
Since the beginning of the 20th century, the volcano has erupted at least 4 times, and at the end of 2021 entered a new period of increased activity.
THE MOST POWERFUL ERUPTION
On January 15 of this year, Hunga-Tonga-Hunga-Haapai caused the most powerful eruption on Earth in the 21st century.
Hunga-Tonga-Hunga-Haapai threw out a column of ash, which rose to a height of 58 kilometers within half an hour.
The explosion of the volcano was felt all over the world.
The eruption triggered a series of tsunamis that caused the deaths of 5 people, and the subsequent waves were recorded at a great distance from the source.
This tsunami has two mechanisms of formation:
- the displacement of the water mass caused by the eruption and
- the propagation of waves in the atmosphere.
The destructive sea waves of atmospheric origin are also called meteotsunamis.
A similar occurrence, where both a localized source and atmospheric processes were involved, was observed after the eruption of the Krakatoa volcano in 1883.
THE STUDY
now, the international team led by Mohammad Heidarzadeh of the University of Bath (England), studied the tsunami waves that were recorded up to 1,500 kilometers from the Hunga-Tonga-Hunga-Haapai volcano.
Since the tsunami was caused by two different mechanisms, scientists analyzed changes in sea level and barometric pressure.
Then the tsunami source was reconstructed.
The model proposed by the researchers does not take into account the contribution of atmospheric processes to the observed tsunami.
However it takes into account only the eruption of an underwater volcano.
Analysis of data from 22 tide sensors showed that the amplitude of the tsunami in harbors and ports ranged from 4.2 to 148.8 centimeters.
The maximum level was recorded off the coast of New Zealand's Great Barrier Island.
The work also used data from eight deep-sea sensors (DART), which are installed at a depth of 1000–5000 meters.
They registered tsunami amplitudes from 3.6 to 21.4 centimeters.
Some of the stations caught high sea waves, which preceded the arrival of volcanogenic tsunamis by 1–2 hours.
As it turned out in the analysis of meteorological data, these early waves in the ocean propagated synchronously with the waves in the atmosphere.
(University of Bath https://bit.ly/3RFMfVg)
The researchers classified them in the category of meteotsunamis.
Then they identified dominant periods of the waves:
- The volcanogenic tsunamis had periods of 10–17 and 4–7 minutes respectively
- The meteorological tsunamis had periods of 7–10 minutes (according to tide sensors) and 30–60 minutes (according to deep-water stations), respectively.
When modeling the volcanogenic tsunami of Tonga, two parameters were taken into account: the initial length of the tsunami and the wave amplitude.
Scientists proposed 9 models, varying in length from 6 to 20 kilometers and amplitude from 30 to 90 meters.
The most realistic option of all was a wave 12 kilometers long with a maximum amplitude of 90 meters.
In this scenario, the volume of water displaced by the Tonga explosion is 6.6×109 cubic meters.
According to the researchers, this estimate is confirmed by measurements at deep-sea stations.
Source:
- Ocean Engineering: https://www.sciencedirect.com/science/article/pii/S0029801822014810?via%3Dihub
- Phys.org: https://phys.org/news/2022-08-tonga-volcano-eruption-metersnine-taller.html
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I learn new information from you. Thanks fir sharing us.
Thank you very much! I love science and I love talking about it. I'm glad you like it <3
Yeah BAD Information. LOL
In ancient times the earth went through very violent stages and this study demonstrates it.
Yup
Why is their only evidence of 3meter waves? LMFAO?
Dear Solar, I certainly don't know why it's their only evidence of 3 meter waves. But that's what the authors mention in their paper (cited in the sources). Feel free to contact them and ask them directly.
Thank you reading my entry,
Sarah.