00:00The ground suddenly starts to shake, while clouds of gas rise and go into the sky, plunging the day into complete darkness.
00:08Some portions of the ground begin to deform, rise or even collapse, so many signs of an imminent eruption.
00:17And this scenario could well be repeated with Mount Spur.
00:20Located at about 120 km from Anchorage, one of the most dynamic cities in Alaska, Mount Spur represents a tangible threat.
00:29More than half of the state's inhabitants, the northernmost part of the United States, reside in Anchorage.
00:34Every day, an immense amount of air traffic passes through its international airport.
00:40Thus, when a volcano located so close to such a crucial crossroads shows signs of agitation, it inevitably attracts everyone's attention.
00:50Informally, about 350 million people in the world live in the risk zone of an active volcano.
00:59This means that 1 in 20 people are exposed to dangers related to a volcanic eruption.
01:05Alaskans would undoubtedly hope that the awakening of Mount Spur is fiction, but the reality is quite different.
01:12The Alaska Volcanological Observatory has recorded several characteristic signs of an imminent volcanic activity.
01:18To the point that the alert level has been raised to yellow, indicating an agitation exceeding the usual levels.
01:27Mount Spur erupted twice in the 1990s, and these events were quite powerful.
01:33On a scale of 1 to 10, they would probably get a grade of 6 or 7.
01:39Without being catastrophic, they nevertheless caused damage estimated between 10 and 17 million dollars.
01:46However, these figures seem ridiculous compared to the eruption of Mount Spur in Alaska in 1988,
01:53another volcano that caused astronomical damage, totaling 345 million dollars.
02:00The main reason lies in the volcanic ashes that disrupted the engines of the planes,
02:04like the KLM 747, whose engines stopped under the effect of ashes before restarting in extremis.
02:12If the unstable geology of Alaska had so far aroused little attention, this event undeniably changed the situation.
02:21When we mention the risks related to volcanism, the first image that comes to mind is often that of Pompeii, in Italy.
02:28Of course, this is the most dramatic scenario.
02:32A city engulfed by lava.
02:34Compared to Vesuvius, Mount Spur may seem less threatening, but it still left notable traces.
02:41During its last eruption in the 90s, it propelled volcanic aerosols at an altitude of more than 18,000 meters.
02:50Let's clarify an essential scientific point.
02:53Volcanic aerosols are liquid particles that are released into the atmosphere during an eruption.
02:59They are generally formed when volcanic gases, such as sulfur dioxide, interact with water and other particles in the air.
03:08These aerosols have the ability to cool the Earth's surface by directly reflecting the sunlight into space.
03:15The worst part?
03:16They can remain in the atmosphere for several years after an eruption, causing serious health problems.
03:23The eruption released flashing avalanches of burning gas and ash, called pyroclastic flows.
03:29Accompanied by thick, bubbling crusts, known as laars.
03:34Not to mention the gigantic blocks of volcanic rock.
03:37Some of them were over a meter in diameter and were projected out of the volcano,
03:41with the power of real cannonballs, crashing down to more than 10 kilometers away.
03:47The heat released melted part of a nearby glacier,
03:50triggering streams of debris that obstructed the Chacachatna River and formed a new lake in the valley.
03:58Despite everything, the first eruption of Mount Spur had a positive effect.
04:03The main lesson learned was the importance of volcanological surveillance.
04:07Thanks to local control systems, economic losses could be limited,
04:12which is essential for a city whose air traffic is so dense.
04:16Although considered as currently dormant, Mount Spur remains unpredictable and could erupt at any time.
04:23Volcanoes are generally classified into three categories.
04:26Active, dormant or extinct, depending on their level of activity.
04:30An active volcano still grows and erupts with a certain regularity.
04:36A dormant volcano has shown signs of recent activity, but is currently asleep.
04:42As for extinct volcanoes, they have been silent for so long that it is estimated that they will never wake up again.
04:50Among the most formidable active volcanoes in the United States is Mount St. Helens,
04:55responsible for the most violent eruption in the history of the country.
04:59During its last explosion, the intensity of the blast took about 400 meters from its summit,
05:04literally making the top of the mountain disappear.
05:07If Mount Spur's ash cloud seemed spectacular to you,
05:11St. Helens' cloud surpassed it by reaching 24 kilometers in altitude,
05:15plunging the east of Washington state into total darkness.
05:20But that's not all.
05:22In just three minutes, the eruption projected nearly 3.7 billion cubic meters of incandescent and dust rocks,
05:30enough to fill a million Olympic pools on a surface of 600 square kilometers of luxurious forest.
05:37The seismic shocks that announced the eruption had only begun several weeks before May 18, 1980.
05:44Finally, an earthquake of a magnitude of 5.0 caused a gigantic landslide on one of the sides of the volcano.
05:54At the end of this historical eruption, 57 lives had been lost.
05:59Nearly 7,000 large animals, such as deers and wapiti, had perished,
06:04while millions of birds were burying the calcined earth.
06:07Although experts do not expect Mount St. Helens to replay an episode of this magnitude in the near future,
06:14they continue to monitor it closely, because the volcano is far from being extinguished.
06:19For the record, the word volcano derives from Vulcan, the Roman deity of fire.
06:25Eruptions often occur at the meeting point of tectonic plates,
06:29these fragments of the earth's crust that come together like a puzzle.
06:33The famous belt of fire, located in the Pacific Ocean, constitutes the most active volcanic zone on the globe.
06:40It houses between 750 and 915 active volcanoes.
06:45The largest volcano of the belt of fire, and also the largest active volcano in the world, is the Mauna Loa.
06:52Culminating at more than 4,000 meters, it is located in Hawaii.
06:56Researchers estimate that this volcano has been erupting for at least 700,000 years.
07:01The most recent began on November 27, 2022 to end on December 13.
07:06Remained silent since the 1980s, the Mauna Loa finally woke up.
07:11Fortunately, thanks to the continuous surveillance ensured by the Hawaii Volcanological Observatory,
07:17its last eruption was not a victim.
07:20Scientists have invested massively in monitoring volcanoes,
07:24not only to limit economic impacts, but also to save lives.
07:28Their latest ambitious project is to forest directly in the volcanoes.
07:34Recently, scientists have made a trip to Iceland, a true volcanic hot spot.
07:40This country alone has nearly 33 active volcanoes.
07:44However, the one that particularly catches their attention is the Krafla Volcanic System,
07:50which has experienced about 30 eruptions in the last millennium.
07:54The most recent, dating from the mid-1980s.
07:57The Krafla Magma Testbed project, or KMT,
08:00aims to better understand the behavior of magma under the earth's surface.
08:06One of the main advantages of these drilling researches is the prediction of the risks of eruptions.
08:10But they also offer an opportunity to advance geothermal energy.
08:15Imagine a world where electricity would be powered by a source of energy
08:19as inexhaustible as the power of volcanoes.
08:22The KMT project team plans to start deep drilling in 2027,
08:28with the goal of reaching more than 1 km underground.
08:32Monitoring lava activity when it is on the surface is one thing,
08:36but studying it when it remains confined underground is another.
08:40According to the researchers, this approach will allow to truly listen to the earth's pulse.
08:46According to them, these researches could be as revolutionary as the conquest of the moon.
08:52And speaking of that, did you know that volcanoes existed elsewhere in the solar system?
08:57Yes, other planets and moons also shelter them.
09:01The largest known volcano is Olympus Mons, located on Mars.
09:05It is a shield volcano similar to those of the Hawaiian Islands,
09:08but it is nearly 600 km wide.
09:11If brought to Earth, it would cover almost all of Poland.
09:14Impressive.
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