Imaginez un volcan si puissant qu'il a crié avant d'exploser ! 🌋💥 C'est exactement ce qui s'est passé avec Hunga Tonga-Hunga Ha'apai, et les scientifiques ont été totalement stupéfaits. Cette éruption n'était pas seulement grande — elle a envoyé des ondes de choc autour du monde, déclenché des tsunamis, et même atteint l'espace ! Mais la partie la plus folle ? Elle a émis un son mystérieux qu'aucun volcan n'avait jamais fait entendre auparavant. Qu'est-ce qui a causé ce phénomène bizarre, et qu'est-ce que cela signifie pour les éruptions futures ? Regardez la vidéo maintenant et découvrez l'histoire époustouflante du volcan qui a crié ! Animation créée par Sympa.
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Musique par Epidemic Sound https://www.epidemicsound.com
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Nos réseaux sociaux :
Facebook: https://www.facebook.com/sympasympacom/
Instagram: https://www.instagram.com/sympa.officiel/
Stock de fichiers (photos, vidéos et autres):
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https://www.eastnews.ru
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Si tu en veux encore plus, fais un tour ici:
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FunTranscript
00:00We are January 15, 2022. It is 4.47 p.m. local time. The eruption is about to begin.
00:08Do you feel these tremors? The South Pacific is about to be the scene of one of the most intense volcanic eruptions ever recorded by modern technology.
00:18It occurs in the underwater volcano Oonga Tonga Oonga Haapai, nestled in the Tonga archipelago.
00:25The eruption is of exceptional magnitude, with a volcanic explosiveness index of at least 5 on a scale that culminates at 8.
00:33Its intensity is comparable to that of historical disasters such as the eruption of Mount St. Helens in 1980 or Vesuvius in 1979.
00:43It projects nearly 10 km3 of volcanic material into the atmosphere and releases more than 150 million tons of water vapor into the stratosphere.
00:54Such a quantity of water vapor would be enough to fill 5,000-8,000 Olympic pools.
01:00The eruption also generates the fastest underwater currents ever observed and triggers devastating tsunamis reaching regions as far away as Peru,
01:10more than 1,000 km from the volcano. At least four people are found dead there, while others have disappeared.
01:18The most stupefying thing is that a precursor sign appeared just 15 minutes before the eruption.
01:25As this happens frequently, it has not been detected.
01:30Two seismic stations located about 750 km from the volcano, an unusual distance for this type of phenomenon,
01:38have detected a Rayleigh wave, a seismic wave that spreads to the surface of the globe.
01:44It was caused by a fracture of the ocean floor, where magma and seawater began to interact under extreme pressure,
01:52probably at the origin of the eruption.
01:55Usually, seismic signals related to volcanic eruptions are discreet and can only be detected at immediate proximity to the volcano.
02:04But this Rayleigh wave traveled an exceptional distance and displayed an unusual intensity.
02:11This is evidence of a considerable underground activity before the eruption.
02:15If the inhabitants did not feel anything, the remote sensors did not fail to record this phenomenon.
02:21And this progress is a precious progress for the anticipated detection of volcanic threats and the improvement of early warning systems.
02:29If scientists manage to identify these precursor signals, they could alert the populations ahead of an eruption.
02:37This would offer a precious time for evacuation and would limit losses,
02:42especially in the case of underwater volcanoes like this one, which can also trigger devastating tsunamis.
02:50Although the eruption was of considerable magnitude, its impact remained relatively contained.
02:55However, this discovery highlights the essential role of seismic data in the anticipation and management of these phenomena.
03:03If this precursor signal did not allow to issue an alert during this eruption,
03:07the prospect of a real-time use of this information during future events seems promising.
03:13This is particularly true for underwater eruptions, which, against all odds,
03:18could offer a longer warning delay than we imagined.
03:21Even if this warning signal would not have been perceptible to the human ear,
03:25there are sounds of such intensity that they can be literally fatal.
03:29Such sounds are extremely rare, but the most powerful sound ever recorded
03:34did indeed cost the lives of those who were nearby.
03:38On August 27, 1883, the eruption of the Krakatoa volcano in Indonesia
03:44generated the most deafening sound ever measured, reaching a stupefying level of 310 decibels at the source.
03:51To give an order of magnitude, an electric drill produced about 98 decibels,
03:57while the roar of a reactor reached 140 decibels.
04:01From 180 decibels, a sound is capable of causing irreversible injuries to auditory tissues.
04:08During the eruption of the Krakatoa, the noise exceeded 170 decibels at a distance of 160 km.
04:15And at only 60 km from the explosion, sailors had their eardrums pierced.
04:21The deflagration resonated with such intensity that it was heard up to 4,800 km away.
04:28In Alice Springs, in Australia, located more than 3,500 km from the volcano,
04:33shepherds claimed to have seen what they were taking for gunshots.
04:37The Krakatoa's sound wave went around the globe several times,
04:41even if no one heard it beyond 4,800 km.
04:45Instruments recorded brutal increases in atmospheric pressure up to Canada and England,
04:51a proof that the acoustic wave generated by the eruption went around the entire planet.
04:57Sounds exceeding 150 decibels can be extremely dangerous for the body.
05:03An exposure to levels ranging from 170 to 200 decibels can cause fatal injuries,
05:09notably the burst of the lungs.
05:11As for sounds exceeding 240 decibels, they cause injuries of extreme gravity,
05:16it is better not to know the details.
05:18Let's just say that this type of phenomenon is common in cartoons, but very rare in reality.
05:24The scientific explanation behind this phenomenon
05:27is based on the fact that sound is above all a pressure wave,
05:30capable of spreading both in solids and liquids.
05:35When a noise reaches an extreme intensity, it can even cross the human body.
05:40If the pressure generated is sufficient, it can cause the rupture of the lungs
05:44as well as internal organs, causing serious injuries, often fatal.
05:49Volcanoes often trigger small shakes before an eruption.
05:54And they also produce a particular sound phenomenon called harmonic tremor.
05:59This sound manifests itself in the form of a rumbling whose frequency gradually increases
06:04before abruptly stopping just before the eruption.
06:07This type of signal has been recorded on many volcanoes around the world.
06:11However, what makes the Ridout volcano in Alaska unique
06:15is that these tremors are of such intensity that they are perceptible to the human ear,
06:20giving the impression that the volcano is making a real scream before the eruption.
06:25According to a geophysicist at the University of Washington,
06:28the frequency of the harmonic tremor of Mount Ridout reaches such a level
06:32that it is audible only in the form of a slight low rumbling.
06:36Even when it reaches its maximum, this tremor far exceeds those recorded on other volcanoes,
06:42questioning the scientific models used so far to explain these phenomena.
06:48Faced with these observations, researchers had to develop a new approach
06:52to account for these particularly high tremors.
06:55Most of the volcanic sounds come from the vibrations of magma bubbles
06:59when they rise through the cracks in the earth's crust.
07:02But in the case of Mount Ridout,
07:04scientists believe that the harmonic tremor and the shaking that accompanies it
07:08are linked to the passage of magma under extreme pressure through a narrow opening.
07:13Inside the volcanic conduit, this passage connects the magmatic chamber to the crater.
07:18The magma, particularly viscous, adheres to the rocky walls.
07:23As the pressure increases, it progresses slowly before sticking together again,
07:28until the accumulated force pushes it to move again.
07:31These sudden movements generate small shakings,
07:34which become more and more frequent under the effect of pressure,
07:37until they merge into a continuous and increasingly high rumbling.
07:41In other words, it is the rocks themselves that produce this sound.
07:45This new model of interpretation is essential,
07:48because it could allow researchers to better understand the eruptive cycles of volcanoes like Mount Ridout.
07:54It could also play a role in early warning systems.
07:58When Mount Ridout began to produce this cry,
08:01the eruption had already begun for several days.
08:04The tremor often provides only a short lapse of time,
08:07from a few minutes to a few hours, before a new explosion.
08:12In the case of Mount Ridout, it reaches an extremely high frequency
08:16before suddenly stopping,
08:18plunging into a distressing silence just before the resumption of the eruption.
08:22This pause corresponds to a slowdown of seismic activity,
08:26where the two sides of the fault slide gently against each other.
08:30Perhaps this is the stage where even seismic shakings are no longer able to follow the evolution of the phenomenon.
08:36This new model of analysis could also apply to other volcanoes,
08:40such as the Soufrière of the Caribbean island of Montserrat.
08:44Researchers are now trying to understand
08:46why the pressure inside Mount Ridout seems to be concentrated in a specific point.
08:51In order to continue their investigations,
08:53they made two recordings of the seismic activity of the volcano.
08:57The first, of a duration of 10 seconds,
08:59condenses about 10 minutes of seismic signals and harmonic tremors,
09:03accelerated 60 times.
09:05The second, one minute long,
09:07summarizes nearly an hour of activity,
09:09including more than 1,600 small earthquakes
09:12that preceded the first explosion of Mount Ridout,
09:15accompanied by a harmonic tremor.
09:17These recordings are a precious resource
09:20to better understand the mechanisms of volcanic eruptions
09:23and their precursor signs.