00:00The most powerful earthquake ever recorded in the east of the Mississippi River,
00:05which occurred more than 200 years ago, is never finished, according to some scientists.
00:10Most earthquakes last from a few seconds to a few minutes,
00:14and the official record so far is a silent earthquake in Sumatra that lasted 32 years.
00:19This event of slow gliding triggered a massive earthquake and a tsunami.
00:23So, if it's true that the earthquake in New Madrid is still sending replicas,
00:28we'll have a new name for this sad list.
00:31The earthquake began in December 1811,
00:35by a powerful quake in a small part of northeastern Arkansas.
00:39The quakes were felt at a distance of 1,600 km from the White House,
00:44and the towers' bells rang in Boston, even further away.
00:47It even made the powerful Mississippi flow upside down for a few minutes
00:51on new waterfalls formed by the displaced soil.
00:54The city of New Madrid, in Missouri, completely disappeared in the disaster.
01:00The earth would not remain still until the end of January of the following year,
01:04when things became serious again.
01:07A huge earthquake struck, this time near the Ohio River junction and the Mississippi Rivers,
01:13right in the heel of the Missouri Bottom.
01:16Geologists think it was a rupture on the New Madrid fault,
01:20putting even more pressure on the Real Foot fault nearby.
01:23Just when people thought it couldn't get any worse,
01:26two more weeks of tremors passed,
01:28and the Real Foot fault sank deep under New Madrid.
01:31In Tennessee, about 24 km south of New Madrid,
01:35the rise of the ground created the Real Foot Lake.
01:38Steamboats sailed along the river,
01:41with thousands of floating trees and hectares of wood torn by the earthquake.
01:45In St. Louis, Missouri, which is 257 km away,
01:50the buildings were seriously damaged,
01:52and the chimneys fell in Cincinnati, Ohio, 644 km away.
01:58People up to Montreal, Canada, more than 1,600 km away,
02:03felt the earthquake.
02:07Seismologists have recorded about 200 small earthquakes
02:11in the New Madrid seismic zone each year since 1974.
02:16Some researchers estimate that up to 30% of these
02:20were replicas of these great earthquakes that occurred in 1811 and 1812.
02:26In some parts of the United States, where there is not much tectonic activity,
02:30these replicas could continue to grow for years,
02:33perhaps even centuries, after the great earthquakes.
02:36The replicas are the way the Earth releases all this accumulated tension
02:40from the main earthquake.
02:42When the ground shakes because of the first earthquake,
02:45it exerts a ton of pressure on the nearby rocks.
02:48And when these rocks can no longer withstand this pressure,
02:51they crack, causing even more shakings,
02:54this is the replica.
02:55They can be quite intense, especially just after the main earthquake,
02:59but they weaken over time.
03:03All scientists do not agree that contemporary earthquakes
03:07have a link with those of 200 years ago.
03:10We mainly associate the faults with these lines where the terrestrial plates meet,
03:14but there is an entire network of these just below the center of the North American plate.
03:19They are like relics dating from 750 million years ago,
03:22when North America was part of a supercontinent called Rodinia.
03:26When Rodinia began to dislocate, it left behind its rifts,
03:30weak points of the terrestrial crust that extend in depth,
03:34under modern Midwest.
03:36This could explain the seismic activity.
03:38An international team of geologists decided to take a new look
03:42at three major earthquakes that shook North America,
03:46and put an end to the debate.
03:48They used a new mathematical method called the nearest neighbor.
03:52It states that if earthquakes are too close in space,
03:56time and magnitude could be considered as background independent events,
04:01then we suppose that one triggered the other.
04:04According to the way you look at the figures,
04:06between 10 and 65% of recent earthquakes in the region
04:10could be replicas of these historical earthquakes.
04:13And a huge earthquake that struck Charleston in South Carolina
04:17at the end of the 19th century
04:19could explain up to 72% of earthquakes in the region since then.
04:24But not all places are the same, so the scientific debate continues.
04:31In 1774, the British explorer James Cook noticed a glow in the distance.
04:37It was the volcano of Mount Yassur, Yassur, in Vanuatu.
04:40This ugly boy has been spitting lava and ashes since then,
04:44and it is very likely that he has been doing this for much longer.
04:47The volcano has been on alert since October 2016,
04:50which means that things are really unstable there.
04:53They even delimited a radius of 610 meters around the crater
04:57to keep people safe.
04:59There were low to moderate intensity eruptions,
05:02projecting ashes, gases and steam,
05:05and a few more major explosions
05:07that propelled materials out of the crater.
05:10Satellite images detected some hot spots of sulfur dioxide panning,
05:14showing that Yassur is still a big storm there.
05:18Stromboli, one of the volcanic islands near Sicily,
05:21officially holds the Guinness World Record
05:24as the longest erupting volcano.
05:27It has been a fire show for more than 2,400 years in a row.
05:31The ancient sailors nicknamed it the lighthouse of the Mediterranean.
05:35Most of the time, Stromboli is content to spit splashes.
05:39But from time to time, it spills lava
05:42or projects moderately high fountains.
05:45Sometimes, you could also see eruptions caused by steam.
05:51More than 200 million years ago,
05:53the world underwent a major transformation,
05:56with not one, not two,
05:58but four massive volcanic eruptions that changed everything.
06:01All this happened in Wrangelia,
06:03a large piece of land that was once a supermassive volcano
06:07stretching across what is now British Columbia and Alaska.
06:11This volcanic activity could have helped dinosaurs
06:14to go from the size of a kitten
06:16to that of the giants we saw in Jurassic Park.
06:19It triggered a rainy season of 2 million years.
06:23It made the whole world hot and humid,
06:26and the dinosaurs simply loved it.
06:29Researchers dug deep into the layers of sediment
06:32under an old lake in China to discover its secrets.
06:35They found traces of volcanic ash and mercury,
06:38clear signs of these epic eruptions.
06:41There were carbon signatures showing huge peaks of carbon dioxide levels,
06:45making the atmosphere hot and the rain falling down.
06:49All this happened in four distinct impulses,
06:52each triggered by these monstrous volcanic explosions.
06:57There is a place in a national park not far from Sydney, Australia,
07:01where a fire has been raging deeply underground for at least 6,000 years.
07:06It is called Burning Mountain,
07:08and it is a layer of coal fire
07:10that burns its way through a layer of coal under the surface of the earth.
07:14Once these underground fires begin,
07:16they are almost impossible to put out.
07:19This ball of fire is up to 9 meters wide
07:22and is extremely hot.
07:24But there is no flame. It is burning.
07:26The fire progresses slowly at a rate of about 1 meter per year.
07:30A local farmer saw it for the first time in the 19th century
07:34and believed it to be a volcano.
07:36People who have lived here since the Enlightenment
07:38believe that this place is sacred.
07:40They used it to cook and make tools,
07:43and say that it was born from the tears of a widow
07:45or the torch of a hero.
07:47But experts think it could be a flash of lightning,
07:50a piece of coal that heats up like a summer barbecue
07:52because of the interaction with oxygen.
07:57Some say that it could have burned
07:59long before the time when dinosaurs roamed the earth.
08:02No one knows exactly how long this mountain will burn
08:05or in which direction it will move.
08:08At the moment, coal has enough oxygen to burn for centuries,
08:12even millennia, without human intervention.
08:15The fire heats the mountain like a gigantic oven,
08:18making it crack and crumble,
08:20inviting more oxygen to feed on it.
08:23Even if humans decide to act,
08:25these fires of coal veins require water trucks
08:28and liquid nitrogen to control them.
08:30Several years ago,
08:31explorers noticed that the embers were approaching
08:34a cliff overlooking a small river.
08:36And depending on what the coal vein decides to do next,
08:39we could see spectacular changes here
08:41in the decades to come.
08:43There could be flames there with much more heat,
08:46and the coal veins could sink,
08:48extinguish and extinguish.
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