On January 15th, 2022 at 4:28 pm local time, the Hunga-Honga Hunga Ha'apai volcano in the
nation of Tonga produced its most powerful explosion ever recorded.
This explosion sent a sustained plume of ash more than 20 kilometers or 66,000 feet into
the atmosphere, with small parts of the plume traveling further and reaching a height of
30 kilometers.
Due to this massive eruption, a powerful shockwave raced across large swaths of the Pacific Ocean,
reaching all of Tonga and Vanuatu.
Several of my viewers reported hearing the blast as far away as in Auckland in New Zealand
and Brisbane in Australia.
Even further away, the energetic shockwave was picked up by backyard weather stations
which showed a measurable increase in pressure as far away as in Adelaide.
Back in the capital city of Tonga, tsunami warning sirens blared as buoys placed near
the volcano detected an incoming wave.
15 minutes later, a 2.5 meter or 8 foot high tsunami struck the island of Tongatapu.
Several waves overtopped sea facing barriers, flooding tens of thousands of structures.
A tsunami warning was subsequently issued for parts of New Zealand, Australia, Vanuatu.
These waves continued for a whopping 5,000 kilometers, even causing a small 2.3 foot
high wave to hit the Hawaiian Island chain.
As the tsunami which hit Hawaii was taller than expected, a tsunami advisory was subsequently
issued for the entire US west coast and Alaska.
If you live in those areas it means that you should not under any circumstances be in the
water or on a beach.
The expected 1 to 2 foot high tsunami could easily become a 10 foot high tsunami if very
specific topography exists.
In other words, get away from the beach, especially if the sea starts to retreat which means that
a tsunami is imminent.
What was just described is a still ongoing situation and because this is very preliminary
there is a healthy dose of "we don't know yet" among scientists.
With this being said, here are my thoughts as to what just happened and how a tsunami
was generated.
The Hunga Tonga island represents the emergent summit of a large stratovolcano which is mostly
located below the ocean's surface.
Its several vents are centered around a caldera.
Calderas form when the magma chamber of a volcano is partially drained by a large volcanic
eruption, causing the ground above the magma chamber to collapse downwards like a sinkhole.
This caldera is relevant because the recent eruptions at Hunga Tonga occurred around the
northern edge of the caldera.
In 2008 there were two separate islands, but an eruption in 2014-2015 connected these two
islands.
Then, another eruption occurred in late December of 2021, expanding the island by another 72%.
This latest eruption placed a mass of new volcanic rock right up against the steep cliff
of the caldera.
Thus, the area I have marked on screen became highly structurally unstable and prone to
collapse.
A warning sign of events to come occurred on January 14th, when a small collapse generated
a 30 centimeter or 12 inch high tsunami.
Then, earlier today, an estimated 0.5 cubic kilometers of rock slid into the ocean, generating
a catastrophic tsunami.
This landslide exposed a large body of stagnant magma at shallow depths to ocean water, causing
the water which interacted with it to flash to steam and explode.
Due to the amount of magma present, this generated a sustained eruption plume in an eruption
type used to describe the most energetic eruptions, a plinian eruption.
Based on the evidence available, I estimate that today's eruption would be rated on the
volcanic explosivity index as a 4, indicating an eruption similar in magnitude to the 1902
eruption of Pelee in Martinique.
Due to the vast quantity of falling ash, the day seemingly turned to night across much
of Tonga.
In the upcoming hours to weeks, more smaller tsunamis are quite likely, so residents should
stay away from the shoreline.
When this eruption is over, I either expect a large U shaped crater to be present on the
island of Hunga Tonga, or for the middle section of the island to be completely gone.
Thanks for watching.
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