What Happens Underwater During a Tsunami? | Unveiled


What Happens Underwater During a Tidal Wave? Earth’s oceans stretch out as far as the
eye can see, blue and endless in every direction. But, as mysterious as those infinite horizons
are, at 0.3 billion cubic miles in volume, there’s far more going on beneath the water’s
surface. It’s even speculated that we know less about
what lurks in the furthest depths of our own oceans than we do about the furthest reaches
of outer space… But, one thing we do know, is that Earth’s
seas have the potential to cause complete devastation. It’s all well and good staying away from
the ocean and all of its unknowns, but sometimes the planet forcibly brings the water to us
– via tidal waves, storm surges and tsunamis. And, when that happens, it’s not only people
on the surface who are in danger. Some of the deadliest natural disasters in
history have been tsunamis, with the 2004 Indian Ocean Earthquake and Tsunami killing
almost a quarter of a million people in South East Asia. While their effects on mankind are clear enough,
the effects on the areas they originate from are often hard to see. Technically, all regular waves could be considered
“tidal waves”, since they’re caused by the motion of the tides and, ultimately,
by the gravitational pull of the moon. Tidal waves are really just a typical wave,
only bigger – often thanks to increased winds. On the other hand, tsunamis and megatsunamis
are the most dangerous. Tsunamis aren’t caused by the natural pull
of the moon, but are triggered by seismic activity deep underwater – earthquakes and
volcanic eruptions. The earth’s surface is made up of tectonic
plates, large slabs of crust which move about because of convection currents inside the
planet’s mantle. When these plates come into contact with each
other, the force of a collision or a sudden release of pressure causes an earthquake. On land these are already dangerous enough,
with the deadliest ‘quake on record – in China in 1556 – killing an estimated 830,000
people. But, when they happen at sea they can be doubly
devastating. If the earthquake is close enough to land,
there’s often widespread destruction even before the tsunami hits – and afterwards,
the aftershocks can lead to more danger. However, the distance a tsunami has to travel
before it hits land isn’t what determines how dangerous it is; the danger actually comes
from how deep the epicentre is in the water. The deeper the water, the deadlier the wave. People often find themselves trapped at sea
during tsunamis. Sailors have described the sensation as like
running aground on rocks, even though they’re out in open water with no rocks to be seen. Scuba divers and surfers are also at risk,
although some have beaten the odds to survive partly because they were already in the water
(and a considerable distance out) when the wave gathered pace. For those on land from the outset, the best
bet is always to get to high ground as soon as possible. The same rules are true for lots of sea creatures. Large creatures that prefer deep water will
be able to survive a tsunami with little to no effort, and whales and dolphins are even
capable of sensing changes in pressure when a tsunami draws close. Since one of the primary threats from these
disasters comes from being thrown into objects at great force by the water, in the sea (where
there aren’t any objects) the animals are at much lower risk. Given that the ocean is also their natural
habitat, the human threat of drowning doesn’t exist either. It’s along the immediate coastlines that
things are just as dangerous for animals and humans alike, however. Out in deep water, tsunamis travel very quickly
but don’t rise up; they only begin to gain significant height when they get closer to
the shore, sucking up all the water on the beaches as they approach. This receding of the water is the closest
thing we have to a five-minute tsunami warning; so, if you’re ever on a beach and witness
this happening, you definitely need to run. But, this process can have devastating consequences
for certain sea creatures who live in the shallows and can’t escape quickly enough,
like crustaceans, certain turtles, coral reefs and other ocean flora. Sudden exposure to open air can be particularly
damaging to reefs, especially when the almighty force of the tsunami comes crashing down all
around them. Lots of smaller fish can also suffer if they
can’t get away quickly enough, eventually finding themselves stranded in wrecked buildings
and roads once the initial wave has passed. That’s not to say that animals and environments
found further out at sea are definitely safe… Because, tsunamis are capable of physically
ripping apart the sea floor, causing a kind of underwater landfall, killing reefs and
destroying habitats. However, this destruction doesn’t necessarily
cause long-term problems. A study carried out by Kyoto University on
the long-term effects of the 2011 Tōhoku Earthquake and Tsunami – which was the most
powerful earthquake to ever hit Japan – proved that coral reefs are actually incredibly resilient,
and able to recover at a surprisingly steady rate. Similarly, while there were some problems
with the tsunami bringing invasive species from other parts of the sea, fish populations
soon returned to expected levels. That said, coral reefs are only so good at
repairing themselves when left alone by humans, and pollution is another major threat that
a tsunami poses to the ocean. While the giant waves bring millions of gallons
of water onto land, they also take significant parts of the land back out to the sea with
them – when they eventually return. In fact, the same 2011 tsunami in Japan led
to four times as much ocean pollution being recorded. There was a massive influx in waste plastic
and other non-biodegradable objects in the surrounding waters, but also across the globe
as up to 100,000 pollutant items landed on the coast of North America in the four years
after the tsunami – reportedly as a direct result of the disaster itself. Given that human-triggered ocean pollution
is one of the main ecological concerns of this generation, the long-term environmental
effects of a tsunami are constantly monitored. However, it’s also true that the seas would
be polluted by such a wave regardless of human influence, because of naturally-occurring
sedimentation – when excess soil and dirt from the land is dragged back into the water. With or without humans, this would always
happen whenever a big enough wave strikes, and it can have an impact on some species
evolution – although it isn’t likely to permanently damage marine ecosystems. Evidence exists of all of these things – sedimentation,
displacement of wildlife, and damage to the sea floor – dating back to prehistoric tsunamis. The Eltanin Impact, for example, happened
off the coast of South America approximately 2.15 million years ago, and was caused by
a 4km asteroid crashing into the ocean. Fossil records show that marine life was widely
displaced by this extreme event, which saw a wave that may have been as tall as 660 feet. Tsunamis aren’t the only waves we need to
be concerned about, however – nor are they the only ones that can affect sea life. While many fish have adapted to survive storms
which cause increased wave activity, with some even knowing to flee the area if storm
surges get too high, underwater waves pose a different threat entirely. Also known as “internal waves”, they were
extensively researched in a 2015 study on the Luzon Strait in the South China Sea. According to research, internal waves can
be so powerful that they affect the celestial motion of the moon itself, causing it to sometimes
move further away from Earth. While they work in a similar way as waves
on the surface, they’re much vaster, and most of them are the size of skyscrapers. In fact, the average height of these underwater
events is the same as the most extreme surface tsunamis ever known. The largest surface tsunami on record is the
1958 mega-tsunami in Lituya Bay, Alaska – which was 1,700 feet tall! All internal waves are to this scale, however. And, while they’re typically slow-moving,
they’re a relatively common phenomenon – churning warm water with cold, and irretrievably changing
underwater landscapes. So, while deadly surface waves pose the biggest
(and most obvious) threat to us, the mysteries of the deep remain as bountiful as always. But the underwater world is, in general, better-adapted
to deal with these disasters than humans are; after all, internal waves are just a fact
of life for deep sea creatures, rather than a frightening revelation. What happens underwater during a tidal wave? Well, besides the coastal creatures in shallow
waters, the majority of sea life can endure even the most extreme situations… It’s those of us living on land that face
the gravest danger.

18 thoughts on “What Happens Underwater During a Tsunami? | Unveiled

  1. It's well known that tidal waves are sent by Poseidon when foolish mortals don't offer sacrifice when they cross his oceans.

  2. I think the title could be better phrased, tsunamis and tidal waves aren't the same thing (sorry to be mildly pedantic, but it's the one thing I studied in geography I actually remember lol)

  3. Damn our Earth is deep af bro.

    Edit: now that i think of it, zoom out really deep in the universe. What can be out there? What if there could be life floating anywhere out there?

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