• 21 hours ago
Underwater avalanches, or "submarine landslides," might sound like something out of a sci-fi movie, but they’re a real danger! 🌊 These events happen when large amounts of sediment or debris suddenly slide down the ocean floor, causing massive disturbances. The force from these avalanches can trigger huge tsunamis, traveling across the ocean and hitting coastal areas with little warning. 🌊 The scary part is that they’re hard to predict, especially because they often happen in deep, remote parts of the ocean. Scientists are studying them more to understand the risks, but the danger is real. It’s a reminder that the ocean can be as unpredictable and powerful as anything on land! Animation is created by Bright Side.
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Transcript
00:00The snowpack over your head splits in two right in front of your eyes and starts tumbling
00:06down in the frozen slope to its resting place far, far below.
00:10Anything in its way is crushed under the immense mass of snow and debris.
00:15You're witnessing an avalanche, one of the most dangerous natural disasters.
00:21But what if I tell you about another kind of avalanche, no less blood-chilling than
00:24the mountain one?
00:26And the most bizarre thing about it is that it occurs underwater.
00:32Underwater avalanches are powerful and disastrous natural phenomena, often much more dangerous
00:37than land ones.
00:39They have the potential to wreak havoc on the entire planet, leading to catastrophic
00:43consequences.
00:44The most alarming thing?
00:46They occur all the time under the surface of the ocean, impossible to see, predict,
00:51and extremely difficult to measure.
00:55Such avalanches can get 100 times larger than land ones, and they pose a great risk
01:00to the world's communications, capable of leaving the entire planet without the internet.
01:06But we'll talk about it a bit later.
01:09First let's go 60,000 years back into the past.
01:13We're near the northwest coast of Africa, ready to witness the colossal scale and devastating
01:19impact of a ginormous underwater avalanche.
01:22It started as a quite small underwater landslide in the Agadir Canyon.
01:28At first it was just 0.35 cubic miles of material, but in no time this mass increased more than
01:36100 times in size while traveling across the Atlantic ocean floor.
01:41As the avalanche sped up and grew, it picked up gravel, sand, rocks, and mud.
01:47It carved a devastating path through one of the world's largest submarine canyons, wiping
01:52out all forms of animal and plant life on its way.
01:56The disastrous flow was so powerful that it literally eroded a 250 mile stretch of the
02:02canyon, cutting hundreds of feet into its sides and damaging a total area of 1,740 square
02:09miles.
02:10That's the area of more than three and a half New York cities!
02:15As for the force of the flow, it was so immense that it propelled massive boulders up the
02:20canyon walls to heights of up to 430 feet.
02:25Before scientists discovered the evidence of this catastrophic event, they had seriously
02:30underestimated the scale of destruction caused by submarine avalanches.
02:36By the way, these devastating catastrophes can start not only far away in the ocean,
02:41but also at estuaries.
02:44Let's go back to 14 January 2020 and see for ourselves.
02:49A turbidity current, a rapid, downhill flow of water containing a lot of sediment, rushed
02:55more than 680 miles from the Congo River estuary in the deep sea.
03:00This current appeared due to two factors, terrible flooding along the Congo River in
03:05late December 2019 and unusually large spring tides.
03:10This resulted in an avalanche of sand and mud.
03:13Its volume was equivalent to one third of all the sediment produced annually by all
03:17the rivers in the world.
03:20This sediment avalanche accelerated, increasing in speed from 17 feet per second in the upper
03:25part of the Congo Canyon to 26 feet per second when it reached the end of the channel, almost
03:30700 miles away from the coastline.
03:34This route made it the longest avalanche of sediment ever measured on our planet.
03:39Two days later, the flow reached the deep ocean.
03:43The avalanche broke two seabed telecommunication cables, cutting internet data speeds all the
03:48way across West, Central, and South Africa.
03:52Now, before this disaster, scientists considered that measuring powerful deep sea avalanches
03:59was impractical.
04:00But the sediment flow in the Congo Canyon could be monitored directly, finally allowing
04:05researchers to assess how major river floods connected to the deep sea.
04:10They also concluded that how often underwater avalanches occurred depended on where the
04:15observer was.
04:18Seafloor canyons that are close to river mouths can experience several tiny avalanches per
04:22year.
04:23Other systems, far from river discharges like the Agadir Canyon, can only have one monster
04:29of an avalanche every 10,000 years or so.
04:33You're likely wondering, what can trigger an avalanche under the surface of the ocean?
04:38Well, earthquakes, typhoons, high tides, river floods, and even volcanic eruptions.
04:45And due to our changing climate, such events become more and more frequent and intense.
04:50At the same time, these triggers don't mean that an avalanche is bound to happen, nor
04:55do they relate to the scale of the event.
04:58See for yourself.
05:00In 1755, a powerful earthquake hit the coast of Portugal, wiping out large parts of Lisbon.
05:07Tens of thousands of people lost their lives during that disaster, but it only triggered
05:12a tiny underwater avalanche.
05:15And in 1929, a large earthquake off the coast of Newfoundland, Canada triggered the largest
05:21underwater avalanche ever recorded.
05:24The flow traveled at a speed of 42 miles per hour, carrying boulders, sand, and mud.
05:30It snapped 11 seabed cables on its journey downhill.
05:34The avalanche was so powerful, it produced a tsunami that claimed the lives of 28 people
05:40along the coastline.
05:41Now, submarine avalanches are totally invisible because they happen deep under the ocean surface,
05:48which makes them extremely hard to study.
05:51But we must find a way, because these flows are super important.
05:56They transport sediments, nutrients, and even pollutants across the ocean floor.
06:01So, a research team from Liverpool decided to unravel this mystery.
06:06Over the last 40 years, they've collected more than 300 samples from the ocean floor.
06:12Combined with seismic and bathymetric data, which is a fancy word for ocean mapping, they
06:17managed to reconstruct a massive submarine avalanche.
06:22It was the first time an underwater avalanche of this size was mapped out.
06:26An even cooler thing, the event itself started off pretty modestly, but it quickly evolved
06:32into a colossal avalanche that grew to more than 650 feet tall.
06:39To put that into perspective, imagine a skyscraper-sized avalanche zooming from Liverpool to London,
06:46cutting a trench 100 feet deep and 9 miles wide.
06:51Then it spread out over an area bigger than the UK, covering it with several feet of sand
06:56and mud.
06:57That's like burying a whole country.
07:01These findings are actually a big deal, because they show that even a small underwater landslide
07:06can turn into something massive and super destructive.
07:11But that's not the worst.
07:12Think about undersea internet cables, which are essential for global communication.
07:17There are more than 550 active seafloor cables around the world.
07:22Their combined length is a whopping 870,000 miles.
07:27That's enough to wrap around our planet 35 times.
07:31When a submarine avalanche breaks seafloor cables, the effects are usually super expensive
07:36and devastating.
07:38For example, in 2006, an earthquake in Taiwan triggered underwater avalanches that cut loads
07:44of seafloor cables connecting Southeast Asia with the rest of the world.
07:49The largest internet operator in China had a 90% loss of traffic to the USA at the peak
07:54of the event.
07:56As for Taiwan itself, it experienced between 74 to 100% loss in traffic to neighboring
08:02islands.
08:04So now you probably get why we need to learn more about this natural phenomenon.
08:09Luckily, researchers at Tulane University have found a way to study it in 3D.
08:15Previous studies only looked at submarine avalanches in 2D, which didn't give the
08:20full picture of how they actually behaved.
08:23The new research focused on how underwater flows interacted with mini-basins, natural
08:28features on the ocean floor that look like shallow bowls.
08:32Despite being called mini, these bowls can be huge, up to 4 square miles.
08:40When turbidity currents flow into these mini-basins, they don't just stop.
08:45They hit the far side and curl back around, like water eddies in a stream.
08:50These swirling flows move the sediment around before it settles on the ocean floor.
08:55The size of the mini-basin and the speed of the flow can change how the current behaves.
09:01If the basin is big, and the current is slow, it starts to fill up with sediment.
09:06But if you crank up the flow speed or shrink the basin, the current starts to overflow,
09:11spilling over the basin.
09:13To study all this, the researchers created a mini-version of a mini-basin in a pool and
09:18used different speeds of flow to simulate turbidity currents.
09:22They even made their own sediment mixers to see how different sizes of particles would
09:27behave.
09:28In the end, they managed to mimic real-life ocean conditions, but on a smaller, manageable
09:33scale.
09:35Pretty cool, huh?
09:36That's it for today!
09:38So hey, if you pacified your curiosity, then give the video a like and share it with your
09:42friends.
09:43Or if you want more, just click on these videos and stay on the Bright Side!

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