Approximately 1 year ago on this date, the unthinkable happened at a little known island
volcano within the nation of Tonga.
A slightly more than 2 mile wide island exploded in the largest explosive volcanic eruption
of the 21st century in an eruption which was likely at a minimum a little more than 7.5
times larger than the highly destructive 1980 eruption of Mount Saint Helens.
Whereas beforehand the Hunga Tonga Hunga Ha'apai volcano had two interconnected islands on
the northern rim of a large primarily submarine volcano, in the aftermath this island not
only split in two but the center of this volcano lost 750 meters or 2,460 feet in height as
a several kilometer wide section of it collapsed into a caldera.
Before the eruption the two previously separated islands were lush, green, and densely forested.
And now, with footage courtesy of Taaniela Kula, Pupunu Tukuafu, and Shane Cronin, I
can show you what remains of the once highly beautiful Hunga Tonga Hunga Ha'apai complex
above sea level.
All of the trees, vegetation, moss, lichens, and any animals which lived there were completely
annihalated.
However, not all was lost as the sheer cliffs and scarred landscape left by the destructive
eruption are already being visited by and have become the nesting sites of numerous
sea birds.
This video serves to showcase the before and after of the now largely destroyed island,
as the eruption was a testament to the destructive power nature can bring.
First, some background information.
The reason for the unusual name of this volcano which some find hard to pronounce relates
to what used to be two forested and separate islands.
To the east-northeast was the island of Hunga Tonga while to the west-southwest was the
island of Hunga Ha'apai.
After it was discovered that these two separate islands both owed their existence to the same
volcano, the complex received its name of Hunga Tonga Hunga Ha'apai via combining the
names of those two islands.
When the catastophic plinian eruption occurred on January 15th of 2022, the explosive force
of the one or more blasts had an energy equivalent of perhaps as much as the detonation of 18
megatons of TNT.
This blast and the later caldera collapsed destroyed large swaths of the two original
islands.
Now shown is all that remains of the southwestern Hunga Ha'apai island.
The blast separated this island into two portions with volcanic layers that formed the island
now exposed for all to see.
If you are wondering why the island appears tilted down away from the camera, this is
due to uneven subsidence related to the caldera collapse which occurred during 2022.
You might be wondering why the island now has three distinct colors; light brown, black,
and red.
The answer is each of these colors represents a distinct type of volcanic deposit which
originally formed the island.
The brown represents primarily ash deposits produced via either shallow submarine eruptions
or eruptions just barely above sea level, representing island forming surtseyan style
eruptions.
On the other hand, the red represents scoria.
It formed through strombolian style eruptions which intermittently ejected ash and bombs
of lava like commonly seen at the Mount Etna volcano in Italy.
And, the black represents an effusive portion of an eruption as it marks lava deposits which
have a gray to black coloration due to their basalt to andesite composition.
The reason the island seemingly cleaved in a way where mostly scoria and lava rock were
exposed relates to them being much harder than simple ash deposits.
Now, here are the remnants of the original Hunga Tonga island.
The apparent pinnacle like structure at its summit represents the remains of a thick lava
deposit, likely at one point representing a location of a source vent where supplied
molten rock erupted.
The light blue hues in the water you are seeing represent particulates in the ocean which
could be caused by erosion of the Hunga Tonga Hunga Ha'apai edifice above or below sea level,
submarine fumaroles venting gasses, or a combination of both.
Thanks for watching!
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