00:00The last time this volcano erupted was about 500 years ago, but recently, small tremors have grown really frequent,
00:08to such an extent that scientists have been recording more than a thousand a month.
00:13I'm talking about the Campi Flegri supervolcano in Italy.
00:18At one point, just a few weeks ago, the area was rattled by a 4.4 magnitude earthquake with 150 tremors in just one night.
00:28It was the strongest earthquake in over 40 years. A lot of locals spent the night in their cars,
00:34but in the morning, the shakes were followed by another earthquake, a bit weaker, with a magnitude of 3.6.
00:42So, is Italy in danger?
00:45Well, the quake itself wasn't big enough to cause serious damage, but it evoked a lot of panic.
00:51At the moment, local authorities are working on grandiose emergency plans.
00:56If worse comes to worse, they'll have to evacuate hundreds of thousands of people.
01:01One of the reasons is the proximity of this area to Naples with more than 3 million inhabitants.
01:07At the moment, they're even considering an option of paying people to leave their homes.
01:14Right now, schools remain closed in the Campi Flegri area.
01:18The authorities are allocating more than 500 million euros to ensure the safety of buildings and constructions in the area.
01:25A yellow alert is still in place in the region where 80,000 people live.
01:30There's the so-called red zone, which is the most dangerous area.
01:35There are 1,250 houses in this red zone, and all of them will be at high seismic risk if an eruption begins.
01:43Plus, more than twice as many will be at medium risk.
01:48Italy is a country prone to seismic activity, and Pozzuoli is a densely populated area that is located on one of the most dangerous supervolcanoes in Europe.
01:59Campi Flegri has 24 hidden underground craters and dwarfs the better-known Vesuvius.
02:06Yes, the very volcano that wiped the ancient Roman city of Pompeii off the face of the Earth in 79 CE.
02:15This city thrived near the base of Mount Vesuvius at the Bay of Naples.
02:20In the time of the early Roman Empire, 20,000 people lived in Pompeii.
02:25They were merchants, manufacturers, farmers, and others.
02:29The soil in the region was rich and fertile, so there were lots of orchards and vineyards.
02:34Strangely, no one knew that this black Earth was the legacy of an earlier eruption of Mount Vesuvius.
02:41The area was a favorite summer destination for rich Romans.
02:45Sadly, at noon on August 24, 79 CE, all this prosperity came to an end.
02:52The peak of Mount Vesuvius exploded, sending a 10-mile-high mushroom cloud of ash and pumice into the stratosphere.
03:00For the next 12 hours, the eruption was wreaking havoc on the city.
03:05Volcanic ash and a hail of pumice stones, some of which were 3 inches in diameter, showered Pompeii.
03:11It forced the city's occupants to flee in terror.
03:15Around 2,000 people holed up in stone structures and cellars, paralyzed by fear.
03:21They hoped to wait out the eruption.
03:23Who knows, maybe if they had decided to leave the city immediately after the beginning of the eruption,
03:29they would have had some chances to survive.
03:32A westerly wind protected the city from the first stages of the eruption.
03:36But soon, a giant cloud of hot ash and gas rushed down the western slope of Vesuvius.
03:43It engulfed the city, burning everything in its way.
03:47This disastrous cloud was followed by a flood of volcanic mud and rock, which completely buried the city.
03:56As if the volcano was making sure no one would survive, a cloud of toxic gas poured onto the city,
04:02finishing the lives of a few survivors on August 25th.
04:06A flow of rock and ash followed.
04:09It collapsed roofs and walls and turned the city into a giant cemetery.
04:15When a supervolcano erupts, the consequences are usually catastrophic.
04:20Supervolcanoes have at least once had an eruption with a Volcanic Explosivity Index of 8,
04:26which is the largest recorded number on the index.
04:29Supervolcanoes are often extremely large, with no cone at all.
04:34That's because they're typically the remains of gigantic magma chambers that once flared up, leaving behind a caldera.
04:42They're usually located over hotspots and appear when huge volumes of magma are trying to escape from deep underground.
04:49Eventually, they burst through Earth's surface.
04:52Sometimes, all this magma gets stuck, unable to break through the planet's crust.
04:58And then, massive pools of pressurized magma gather at a depth of several miles.
05:04The pressure keeps growing because more and more magma is trying to get to the surface.
05:09At one point, a supereruption goes off.
05:14The most recent supereruption happened in New Zealand.
05:17Well, when I say recent, I meant around 26,500 years ago.
05:23That's when a supervolcano beneath the surface of Lake Taupo spewed into the air more than 300 cubic miles of ash and pumice.
05:32Imagine 500,000 Great Pyramids of Giza flying up into the air at the same time.
05:38That's how incredibly powerful that eruption was!
05:42But the most exciting and confusing thing about the eruption was that the Taupo volcano didn't simply go off like many others.
05:51At first, everything was going as usual.
05:54Tons and tons of pressurized magma had built up under the surface, and the pressure was getting higher and higher.
06:01But after the rock cracked and the first portion of lava rushed out of the crater, something went wrong, and the supervolcano took a break.
06:09Only several months later, the disastrous eruption shook the ground.
06:13Thousands of tons of lava, rocks, and ash flew high into the atmosphere.
06:18The unusual pattern of Taupo still confuses scientists.
06:24The Indonesian eruption at Toba Caldera 75,000 years ago was the largest eruption in the last 2 million years.
06:32Experts estimate that the eruption could have released hundreds of thousands of tons of sulfuric acid.
06:39Which might have even caused a several degree cooling of the planet's surface.
06:43But nowadays, the impact is hard to detect because of glaciers that cover the ground afterward.
06:49There are also several so-called supervolcanoes that haven't lived up to this name yet because they've never produced any super eruptions.
06:57For example, in 1883, Indonesian volcano Krakatoa went off.
07:02The power of the eruption tore the volcano's walls open, and cold seawater rushed into its molten insides.
07:10The difference in temperatures made the volcano blow up with a deafening boom.
07:15It was clearly heard 3,000 miles away in Australia.
07:19It earned the blast the title of the loudest sound in history.
07:23But even though the consequences of this event were truly catastrophic, it still turned out not powerful enough to be called a super eruption.
07:33It only had a volcanic explosivity index of 6.
07:38Then, there's also Mauna Loa.
07:41It's a shield volcano, which means it won't produce explosive eruptions.
07:45But its sheer size makes this monster of a volcano extremely dangerous.
07:51At the moment, the volcano seems to be at peace with its surroundings.
07:56Research equipment doesn't show any signs of activity on Mauna Loa.
08:00But if Mauna Loa did suddenly erupt, lava flows could reach the ocean and the most populated and touristy places like Captain Cook very fast, in a matter of hours.
08:11The last time the volcano erupted, lava got as far as the outskirts of Hilo on the other side of the island.
08:19That's where the University of Hawaii is located.
08:22Luckily, people had a few weeks' warning to get ready for the disaster.
08:26Over its recorded history, Mauna Loa has been erupting pretty regularly, almost every six years.
08:32On the bright side, big island volcanoes including Mauna Loa aren't really very volatile.
08:38That's because they're shield volcanoes.
08:41These volcanoes got such a name because they aren't really very high and resemble a warrior's shield placed flat on the ground.
08:48Shield volcanoes are formed by very fluid lava.
08:51It travels way farther and forms much thinner flows than the lava erupted from a stratovolcano, which is conically shaped and tall, like the infamous Krakatoa in Indonesia.
09:03So, if Mauna Loa erupts, there probably won't be ash clouds or tons of debris.
09:09The most dangerous thing will be lava.
09:11Since Mauna Loa is a shield volcano, its lava is extremely fluid and voluminous, which allows it to flow far and fast.
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