00:00On January 14, 2022, residents of Anchorage, Alaska heard a series of loud bangs.
00:07They didn't stop for a half an hour.
00:10As they found later, the source of the bangs was almost 6,000 miles away
00:15in the Tongan Archipelago in the Southern Pacific Ocean.
00:18The Hunga Tonga underwater volcano abruptly woke up from its sound sleep.
00:31It last erupted at the end of December 2021 after several years of inactivity.
00:37Hunga Tonga sent a large plume of ash into the stratosphere that was seen in the capital city of Tonga,
00:4443 miles away from the volcano.
00:46In the following days, it was emitting steam and gas to the height of 7 miles.
00:52Plus, it was letting out ash that accumulated next to it
00:55and even made the island on which it was standing increase in size.
01:00Then it went back to sleep.
01:02And the officials even announced it was dormant.
01:05But just a couple of weeks later, it woke up again with a crazy force.
01:10It sent ash clouds 12 miles into the atmosphere.
01:14It blocked the sun in some places and rained down from the sky.
01:19The sound waves from the eruption traveled around the planet several times.
01:23People in Fiji heard a sound that reminded them of thunder.
01:27Some booms even reached Canada.
01:30Shock waves went around the Earth four times in Japan and Utah,
01:33and at least twice in Massachusetts.
01:35The eruption caused tens of thousands of lightning flashes.
01:40It also triggered a mega tsunami hundreds of feet high.
01:44It caused damage to buildings and infrastructure, such as underwater cables.
01:49The extreme waves traveled all the way to the California coast,
01:53and there was an unusually high tide along the Pacific coasts of Canada.
01:57Scientists studied seismic data to understand what caused such a massive eruption.
02:02Their research model showed that there was a big blast,
02:06likely because gas got trapped in rocks,
02:09like how a pressure cooker works when it's overcooked.
02:12This blast released a huge amount of energy,
02:15as much as five of the biggest underground nuclear tests.
02:19It all happened under a shallow part of the sea,
02:22where gas-filled rock was trapped.
02:23Now, normally, when a volcano erupts,
02:32the fumes cause a temporary cooling effect on the Earth's surface.
02:36But Hunga Tonga's eruption was different.
02:38It didn't produce many fumes,
02:40but released a massive amount of water vapor,
02:43equal to 60,000 Olympic swimming pools.
02:46The intense heat of the eruption turned vast amounts of seawater into steam,
02:50which then blasted high into the atmosphere.
02:53All that water vapor ended up in the stratosphere,
02:56a layer of the atmosphere that's too dry to form clouds or rain.
03:00Scientists don't have any observations of volcanic eruptions like Hunga Tonga
03:05to predict its long-term effects on our weather patterns.
03:08This is because the only way to measure stratospheric water vapor
03:12is with special satellites,
03:14which have only been around since 1979.
03:16And there hasn't been an eruption similar to Hunga Tonga in that time.
03:21In fact, the Tonga eruption is the most well-recorded blast of its kind in recent history.
03:26Scientists had lots of tools to study it,
03:29like satellites that took pictures from space
03:31and sensors that listened to the vibrations and movements in the Earth.
03:35There was a similar eruption in 1991 at a volcano in the Philippines.
03:40But back then,
03:41they didn't have as many advanced tools as they do now to study it closely.
03:45Experts from different countries looked at satellite data
03:50right after the Hunga Tonga eruption.
03:52They wanted to find out how long water vapor would stay in the stratosphere,
03:56where it would go,
03:57and, of course, what this would mean for the planet and for all of us.
04:02The first big result of the eruption, at least partially,
04:05was a huge hole in the stratosphere
04:07that was hanging on for several months in 2023.
04:10By the time it appeared,
04:12the water vapor had reached the polar stratosphere over Antarctica.
04:16But Hunga Tonga ended up with just a minimal effect
04:20on global average temperatures, at least for now.
04:23Let's just hope it won't repeat the story of Mount Tambora volcano
04:26in present-day Indonesia.
04:29Over two centuries ago, in 1815,
04:31this bad guy interrupted and caused the year without a summer.
04:35In the following year, the winter was unusually cold and wet
04:39across Europe and North America.
04:41There were also some catastrophic tsunamis,
04:44destroying homes that took 10,000 lives
04:46and 80,000 more who fell ill in the aftermath.
04:51Now, you can't miss an event like Hunga Tonga or Tambora eruption,
04:55but some underwater volcanoes are discovered by accident.
04:58A passenger on a commercial flight
05:00looked out her window above the Pacific Ocean
05:03and saw a weirdly colored patch on the water.
05:06She thought it could be an oil slick
05:08or a floating pumice raft,
05:10which is a tell-tale sign of a recent volcanic eruption.
05:13She decided to send a photo of this scene to a geologist.
05:17And that's how scientists found
05:19one of the largest volcanoes in the world,
05:21Havre.
05:22It's hiding about 3,000 feet below the surface.
05:26In 2012, Havre had a massive eruption
05:28that lasted about 90 days.
05:30Hot lava poured out of 14 different vents
05:33around the volcano's semi-circle-shaped opening.
05:37Havre is just one of many volcanic systems
05:39covered by thousands of feet of water.
05:42These volcanoes are the most active on Earth
05:44and are part of a giant system called mid-ocean ridges
05:47that stretches around the world.
05:50This system produces about 75% of all the magma
05:53that comes out of Earth's volcanoes each year.
05:56It releases over half a cubic mile of lava.
05:59When the magma cools down,
06:01it forms the edges of new ocean plates,
06:03which are like giant puzzle pieces
06:05that make up the Earth's crust.
06:08A team of scientists studied material
06:10left on the ocean floor by volcanic eruptions
06:12from the Bronze Age.
06:14About 3,600 years ago,
06:17a volcano that was partly underwater
06:19in the southern Aegean Sea
06:21woke up with a bang.
06:23This eruption destroyed the island of Santorini
06:25and sent massive amounts of ash, rocks, and gases into the air.
06:30It left behind thick layers of ash and rock
06:32that settled in piles on the ocean floor.
06:36Scientists have been studying the ancient Santorini eruption
06:38for several years
06:39to figure out what happens during such massive ones.
06:43Their research helps explain
06:45how future volcanic eruptions
06:47could affect the weather on our planet.
06:48The study also helped scientists
06:51understand the strength of the eruptions,
06:54how high the eruption columns might go,
06:56and the sizes of the waves that form
06:58when all that ash and rock
07:00settles into terraces on the ocean floor.
07:03This information will help predict
07:05the dangers of future eruptions.
07:07Now, when a volcano erupts,
07:09the last place you want to be is inside it.
07:12But scientists did it for you.
07:15Well, kinda.
07:16They produced a smart new imaging technique
07:19that uses the best ideas
07:20from medical imaging and optical telescopes.
07:24Matrix imaging, that's what it's called,
07:26makes it easier to understand
07:28what's happening underground,
07:29even when there aren't many sensors available.
07:32These sensors, called geophones,
07:34detect and record the movement of seismic waves,
07:37which are vibrations that travel through the Earth.
07:40By studying these waves,
07:41scientists can learn about the distinct types of rocks
07:44and how they are arranged beneath the surface.
07:47The researchers test their method
07:49on a volcano in Guadalupe in the Caribbean Sea.
07:52There aren't so many geophones on this site,
07:55but the scientists combined the data
07:57from multiple geophones thanks to this new tech.
08:00They used a special trick called the memory effect
08:03to reverse the distortions that happen
08:05when seismic waves bounce off
08:07different underground materials
08:08and figure out what the original signals looked like.
08:11The researchers could clearly see the structure
08:14inside the volcano down to a depth of about 6 miles
08:18with incredibly detailed images
08:20in a resolution of over 300 feet.
08:23They found out that there are many layers of magma
08:26stored underground.
08:27These layers are connected to other deep parts of the Earth.
08:31Knowing about these layers and how they work
08:33could help scientists make better guesses
08:35about when a volcano might erupt.
08:38If they can do that,
08:40they might be able to warn people earlier
08:42and keep them safe from dangerous eruptions.
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