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Since late December, the Hunga Tonga-Hunga Ha'apai volcano has seen a lot of activity
in a series of pretty big eruptions.
On the 14th January, it was spotted erupting again by local scientists.
This seemingly huge eruption shot ash 20km into the atmosphere, creating a pillar which
stretched high above their view.
But this is all about perspective, the impressive sight from a ground view only appeared like
a tiny little pillar from space.
The next day, this happened.
This eruption, seen by both the GOES West and Himawari-8 geostationary satellites, show
the biggest explosion captured on camera, perhaps ever.
Initial reports state this could dwarf even the biggest man-made nuclear explosion, and
it’s not hard to see why.
Just look at how big the ash cloud is.
If we overlay it over Europe, we can see that it covers an impressive surface area.
Sorry Luxembourg.
Not visible in the satellite images, but detected with radio wave listening instruments, more
than 200,000 lightning flashes were counted in the plume.
Volcanic lightning is still an ongoing topic of study, and we don’t exactly know the
processes that cause it due to the difficulty in studying it, but scientists are starting
to suspect that positively charged particles come from the eruption itself as well as interactions
with ash and the atmosphere.
While the island itself was uninhabited, the islands nearby are.
Damage from volcanoes comes in many different forms.
The most obvious is the ash cloud.
The nearby islands around Tonga have been blanketed, with some news reports saying it
looks like a grey moonscape on these islands now, covered by a thin blanket of ash.
These before and after satellite images are revealing.
Residents here were all told to stay indoors while the ash was falling, as breathing it
in can be damaging to the lungs.
Ash has settled on fresh water supplies, contaminating them.
And what was once a green and colourful place now looks like what would happen if you turned
the saturation on an image all the way down.
This isn’t great for plants initially, as it will block the Sun’s rays from hitting
their leaves.
Although eventually, it will be good for the soil of the islands as volcanic ash is a natural
fertiliser, containing many important minerals.
However, the lightest ash particles didn’t just go horizontally across the atmosphere
but they have also certainly penetrated the stratosphere.
Typically, the Earth’s troposphere and stratosphere don’t mix that well, so if ash gets into
the stratosphere, it will stay there and circulate around the globe for months to years.
The tiniest ash aerosols contain sulphuric acid, hydrogen sulphide and hydrochloric acid.
Interestingly, this may have a very slight cooling effect on the Earth as a whole, as
sulphuric acid, for instance, is known to reflect sunlight back into space.
However, the negative consequences are that eventually these particles will come back
down into the troposphere, where they will return to the surface in rain droplets, or
in other words, acid rain.
The next thing you’ll notice is this incredible shockwave blasting away from the volcano.
The fascinating view is seen best in the infrared, as infrared is better at detecting the slight
change in atmospheric temperature caused by the pressure wave.
The pressure wave travelled faster than the speed of sound, and it was loud.
This video may give you some idea of the scale of this shockwave as it passed by an island
65km away.
To be honest, we can be grateful that everyone’s eardrums didn’t rupture.
However, there have been reports that windows from residences were blasted out by the shockwave.
This pressure wave is believed to have travelled around the world at least 4 times, as detected
by weather stations in various countries.
Across the US, the shockwave wasn’t audible, but the effects could be seen in the slight
fluctuations in air pressure as it passed over the country.
However, the shockwave was heard in places as far away as New Zealand and Australia,
even in Alaska.
Generally speaking, underwater volcanic eruptions don’t cause tsunamis, but simply due to
the scale and sudden nature of this one explosion, it did in fact cause a tsunami, although not
a very big one in the end.
It was still enough to do some damage across the Pacific, however, to coastal regions facing
the eruption.
When news came that a tsunami was possible, boats and ships were put out to sea the face
the wave head on.
As tsunamis reach shore, the amplitude of the wave increases causing it to look much
more visible to a tsunami far out at sea, which is why the wave looks so big here.
These boats are not too far from shore.
The last damage I want to examine is to the volcanic island itself.
This island is very new, it’s only been in existence since 2014.
This is because it lies right on the Pacific and Indo-Australian convergent plate boundary,
a tectonically active area.
Before 2014, it consisted of 2 mostly submerged islands, with the caldera around 150m below
sea level in between them.
It had since erupted, filling the gap, merging the two islands.
As a result, it has actually been studied by NASA themselves to better understand how
water impacts volcanoes, as there are plenty of old volcanoes on Mars that would have also
been surrounded by water.
Scientists wanted to track the erosion of this newly formed island formed in the ocean
to see if there are similarities to the erosion patterns on the literal fields of Martian
volcanoes, potentially providing additional evidence that certain Martian volcanoes were
once also surrounded by oceans of water.
It’s also interesting for scientists to be able to tell exactly how analogous planets
like Earth and Mars really are, despite their differences.
As for Hunga Tonga-Hunga Ha’apai, the ash building the island initially was easily washed
away by the lapping sea water like a sandcastle disappearing to the tide, however after about
6 months the erosion stopped as the ash and seawater actually combined to produce a harder,
more resistant type of rock.
And had volcanic activity stopped for good, Hunga Tonga-Hunga Ha’apai would probably
have remained a small island for many years to come.
However, the force of the January 15th eruption has absolutely decimated the island.
What was one stretch of land only last year is now two separate islands again, with the
caldera disappearing back below the sea level.
However just imagine if one day, Earth was to meet a similar fate to Mars and its sea
was completely drained.
What now looks like a tiny little island to us would still look like a towering 2000m
high mountain from the sea floor.
While volcanoes on our own planet are pretty intimidating, we can take solace in the fact
that an explosion of this size could have been a lot worse for us humans.
Moreover, this particular island will likely continue to be examined by NASA for years
yet, helping us understand our own planet but also our neighbours in the solar system.
And why should we care?
Well, volcanic activity at this scale can have global impacts, and by understanding
their interactions with the atmosphere and oceans, we not only can help predict our futures,
but understand the past on planets like Mars.
I’m guessing that you must find volcanoes interesting if you clicked on this video,
and if you want to know more about other volcanoes around the world, MagellanTV has some great
documentaries on some.
One that I enjoyed is called “Guatemala: Volcanoes on Mayan Territory” where they
talk about the Santiaguito volcano, which despite its size, has only existed for the
last 100 years due to its constant eruptions.
What impresses me so much about volcanoes and this one in particular is how they can
rise up for thousands of metres above the surrounding landscape.
Just look at this view from the top - breath-taking.
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Thanks for watching!
Usually, my videos are more space related, but this view of the eruption from space,
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