This Ocean Disaster Could Shut Down the Entire World

0:00The snow pack over your head splits in two right in front of your eyes and starts tumbling down in the frozen slope to its resting place far, far below. Anything in its way is crushed under the immense mass of snow and debris. You're witnessing an avalanche, one of the most dangerous natural disasters. But what if I tell you about another kind of avalanche? No less blood chilling than the mountain and the most bizarre thing about it is that it occurs under water. Under water avalanches are powerful and disastrous natural phenomena often much more dangerous than land ones. They have the potential to wreak havoc on the entire planet leading to catastrophic consequences. The most alarming thing? They occur all the time under the surface of the ocean, impossible to see, predict, and extremely difficult to measure. Such avalanches can get one hundred times larger than land ones and they pose a great risk to the world's

1:01communications, capable of leaving the entire planet without the internet. But we'll talk about it a bit later. First, let's go 60,000 years back into the past. We're near the northwest coast of Africa, ready to witness the colossal scale and devastating impact of a ginormous underwater avalanche. It started as a quite small underwater landslide in the Agadir Canyon. At first, it was just .35 cubic miles of material. But in no time, this mass increased more than one hundred times in size while traveling across the Atlantic Ocean floor. As the avalanche sped up and grew, it picked up gravel, sand, rocks, and mud. It carved a devastating path through one of the world's largest submarine canyons, wiping out all forms of animal and plant life on its way. The disastrous flow was so powerful that it literally eroded a 250-mile stretch of the canyon, cutting

2:03hundreds of feet into its sides and damaging a total area of 1,740 square miles. That's the area of more than three and a half New York cities. As for the force of the flow, it was so immense that it propelled massive boulders up the canyon walls to heights of up to 430 feet. Before scientists discovered the evidence of this catastrophic event, they had seriously underestimated the scale of destruction caused by submarine avalanches. By the way, these devastating catastrophes can start not only far away in the ocean, but also at estuaries. Let's go back to 14 January 2020 and see for ourselves. A turbidity current, a rapid downhill flow of water containing a lot of sediment, rushed more than 680 miles from the Congo River estuary in the deep sea. This current appeared due to two factors, terrible flooding along the Congo River in late

3:05December 2019 and unusually large spring tide. This resulted in an avalanche of sand and mud. Its volume was equivalent to one third of all the sediment produced annually by all the rivers in the world. This sediment avalanche accelerated, increasing in speed from 17 feet per second in the upper part of the Congo canyon to 26 feet per second when it reached the end of the channel almost 700 miles away from the coastline. This route made it the longest avalanche of sediment ever measured on our planet. Two days later, the flow reached the deep ocean. The avalanche broke two seabed telecommunication cables cutting internet data speeds all the way across west, central, and south Africa. Now, before this disaster, scientists considered that measuring powerful deep sea avalanches was impractical, but the sediment flow in the Congo canyon could be monitored directly, finally allowing researchers to assess how major river floods

4:08connected to the deep sea. They also concluded that how often underwater avalanches occurred depended on where the observer was. Sea floor canyons that are close to river mouths can experience several tiny avalanches per year. Other systems far from river discharges like the Agadir Canyon can only have one monster of an avalanche every 10,000 years or so. You're likely wondering what can trigger an avalanche under the surface of the ocean? Well, earthquakes, typhoons, high tide, river floods, and even volcanic eruptions. And due to our changing climate, such events become more and more frequent and intense. At the same time, these triggers don't mean that an avalanche is bound to happen, nor do they relate to the scale of the event. See for yourself. In 1755, a powerful earthquake hit the coast of Portugal, wiping out large parts of Lisbon. Tens of thousands of people lost their lives during that disaster, but it only triggered a

5:12tiny underwater avalanche. And in 1929, a large earthquake off the coast of Newfoundland Canada triggered the largest underwater avalanche ever recorded. The flow traveled at a speed of 42 miles per hour, carrying boulders, sand, and mud. It snapped 11 seabed cables on its journey downhill. The avalanche was so powerful, it produced a tsunami that claimed the lives of 28 people along the coastline. Now, submarine avalanches are totally invisible because they happen deep under the ocean's surface, which makes them extremely hard to study. But we must find a way because these flows are super important. They transport sediments, nutrients, and even pollutants across the ocean floor. So, a research team from Liverpool decided to unravel this mystery. Over the last 40 years, they've collected more than 300 samples from the ocean floor. Combined with seismic and bathometric data, which is a fancy word for ocean

6:17mapping, they managed to reconstruct a massive submarine avalanche. It was the first time an underwater avalanche of this size was mapped out. And even cooler thing, the event itself started off pretty modestly. But it quickly evolved into a colossal avalanche that grew to more than 650 feet tall. To put that into perspective, imagine a skyscraper sized avalanche zooming from Liverpool to London, cutting a trench 100 feet deep and nine miles wide. Then it's spread out over an area bigger than the UK, covering it with several feet of sand and mud. That's like burying a whole country. These findings are actually a big deal because they show that even a small underwater landslide can turn into something massive and super destructive. But that's not the worst. Think about undersea internet cables, which are essential for global communication. There

7:17are more than 550 active sea floor cables around the world. Their combined length is a whopping 870,000 miles. That's enough to wrap around our planet 35 times. When a submarine avalanche breaks sea floor cables, the effects are usually super expensive and devastating. For example, in 2006, an earthquake in Taiwan triggered underwater avalanches that cut loads of sea floor cables, connecting Southeast Asia with the rest of the world. The largest internet operator in China had a 90% loss of traffic to the USA at the peak of the event. As for Taiwan itself, it experienced between 74 to 100% loss in traffic to neighboring islands. So now you probably get why we need to learn more about this natural phenomenon. Luckily, researchers at Tulane University have found a way to study it in 3D. Previous studies only look at submarine avalanches in 2D,

8:18which didn't give the full picture of how they actually behaved. The new research focused on how underwater flows interacted with many basins, natural features on the ocean floor that look like shallow bowls. Despite being called mini, these bowls can be huge up to four square miles. When turbidity currents flow into these mini basins, they don't just stop. No, they hit the far side and curl back around like water eddies in a stream. These swirling flows move the sediment around before it settles on the ocean floor. The size of the mini basin and the speed of the flow can change how the current behaves. If the basin is big and the current is slow, it starts to fill up with sediment. But if you crank up the flow speed or shrink the basin, the current starts to overflow, spilling over the basin. To study all this, the researchers created a mini version of a mini basin in a pool and used different speeds of flow to simulate

9:20turbidity currents. They even made their own sediment mixtures to see how different sizes of particles would behave. In the end, they managed to mimic a real-life ocean conditions, but on a smaller, manageable scale. Pretty cool, huh?