Ce Volcan a Changé la Température du Globe

Sympa

L'éruption du mont Krakatoa en 1883 a causé une destruction massive avec des cendres et de la fumée entraînant une chute dramatique des températures et un tsunami qui a détruit des navires et des villes. Le gardien du phare a survécu et a averti les autres du danger. De nombreuses victimes ont été causées par des tsunamis et des coulées de boue volcaniques, et pas seulement par l'éruption elle-même. L'éruption a également eu des effets climatiques durables, provoquant une baisse des températures mondiales pendant plusieurs années. Examinons cet événement et d'autres événements naturels qui ont changé notre planète.  Animation créée par Sympa. ---------------------------------------------------------------------------------------- Musique par Epidemic Sound https://www.epidemicsound.com   Pour ne rien perdre de Sympa, abonnez-vous!: https://goo.gl/6E4Xna​ ---------------------------------------------------------------------------------------- Nos réseaux sociaux : Facebook: https://www.facebook.com/sympasympacom/ Instagram: https://www.instagram.com/sympa.officiel/  Stock de fichiers (photos, vidéos et autres): https://www.depositphotos.com https://www.shutterstock.com https://www.eastnews.ru ----------------------------------------------------------------------------------------  Si tu en veux encore plus, fais un tour ici:  http://sympa-sympa.com

Transcript

00:00A gigantic volcano that everyone thought was gone,

00:04woke up one day and projected a cloud of black ash

00:08rising 80 km high,

00:10about 9 times the height of Mount Everest.

00:13Located in present-day Indonesia,

00:15the powerful Krakatoa caused huge tsunamis

00:18that affected ships up to South Africa.

00:20It also altered world temperatures for several years.

00:24The volcanic island of Krakatoa, in the detroit of the probe,

00:27was probably born thanks to another major eruption

00:30that occurred several centuries earlier.

00:32The volcano had not erupted for nearly 200 years

00:35before 1883.

00:36Also, the first earthquakes and explosions in May of that year

00:40took the rivers by surprise.

00:43The ships, taking this very common maritime passage,

00:46began to signal the clouds of ash

00:49rising above the volcano.

00:51Even when it became calm again,

00:53ashes continued to swirl above.

00:56The eruption culminated at the end of August

00:58and was so violent that it literally pulverized the island.

01:02The sound of the explosion was heard all the way to Australia,

01:05almost 5,000 km away,

01:07and was described as a terrible rumble of artillery.

01:10Some say it was the loudest sound ever heard in human memory.

01:14Over the next 5 days,

01:16the shock wave of the eruption,

01:18detected by barometers on various continents,

01:20circled the Earth three and a half times.

01:23Pyroclastic flows

01:25swallowed the slopes of the volcano at dizzying speeds,

01:28covering up to 40 km away.

01:30They destroyed the neighboring islands

01:33and killed 36,000 people.

01:35Tens of thousands more

01:36perished in the tsunamis triggered by the volcano's collapse

01:40in its own caldera.

01:41More than a hundred coastal villages in Java and Sumatra

01:44were completely razed.

01:47The Krakatoa eruption

01:49has thus become one of the most devastating volcanic events

01:52in the history of mankind.

01:56Earth's crust looks like a huge puzzle

01:58made up of large pieces called tectonic plates.

02:01These plates constantly slide against each other along the mantle,

02:04a layer of fused rocks just below.

02:07However, Indonesia is precisely at the heart of a subduction zone,

02:11where the Indo-Australian plate collides with part of the Asian plate

02:15as it moves north.

02:17When the oceanic plate plunges down,

02:19it warms up,

02:21creating ideal conditions for a volcanic hot spot.

02:24The Krakatoa had three summits,

02:26each used as an evacuation for the huge magmatic chamber below.

02:30During a previous eruption, debris had obstructed one of its exits,

02:34causing an accumulation of pressure.

02:36When the Krakatoa finally exploded,

02:39the detonation deeply cracked the magmatic chamber.

02:43This eruption triggered what is called a volcanic winter.

02:47The Krakatoa projected 25 km3 of rocks,

02:50ashes, dust and debris into the atmosphere,

02:53forming a thick veil around the Earth.

02:56These particles dispersed the sunlight,

02:58cooling the troposphere upside down.

03:01This effect lasted for several years.

03:04The northern hemisphere experienced temperatures lower than average.

03:07And in some regions,

03:09the summer temperatures could no longer reach their usual levels.

03:12Southern California also recorded record rainfall

03:16in the months following the eruption.

03:19The sky remained dark in various parts of the globe

03:21for years after the eruption.

03:23Sunsets became real spectacles,

03:26sparkling with red and orange for many months.

03:30An astronomer even assumed that this could have inspired

03:33the cry of Edvard Munch,

03:34whose painting perfectly illustrates the Norwegian sky

03:37the day after the eruption.

03:40The Krakatoa also produced a rare type of halo called Bishop's Ring,

03:44as well as a violet volcanic glow at dusk.

03:48Several years after the eruption,

03:50the moon appeared blue, and sometimes green.

03:52Because some ash clouds contained large enough particles

03:55to disperse the red light, leaving everything but other colors.

03:59Some even observed a lavender blue sun,

04:01and bright clouds at night.

04:04The Krakatoa became the first volcanic eruption

04:08to be studied and documented so extensively.

04:11Between the first ash emissions detected by a ship

04:14and the catastrophic eruption,

04:15scientists managed to organize geological expeditions

04:19to study the volcano and collect samples of its rocks.

04:23These efforts were crucial to better understand volcanic activity.

04:28This volcano remained dormant until the 1920s,

04:31when inhabitants noticed a column of vapor and debris

04:34spilling out of the collapsed caldera.

04:37In a few weeks,

04:38the edges of a new cone emerged above sea level.

04:42After a year, it formed a small island called Anak Krakatoa.

04:46It continues to erupt, but fortunately, without serious consequences.

04:51At least for now.

04:52In April 1815, Mount Tambora caused a massive eruption

04:56that devastated the Indonesian island of Sumbawa.

04:59This disaster destroyed the habitats and killed 10,000 people.

05:04Subsequently, 80,000 others died as a result of respiratory diseases

05:08spread by the eruption.

05:09The following year would be recorded in history as the year without summer.

05:14Cold and humid conditions seized Europe and North America,

05:18causing unexpected cooling.

05:20This was the coldest summer period in nearly 250 years.

05:24Temperatures dropped significantly,

05:27preventing crops from growing,

05:29decimating livestock,

05:30and provoking famine in the West.

05:32In New England, strong frosts were even observed during the summer.

05:36Food prices skyrocketed,

05:39drilling for horses was a real luxury.

05:42Some even claim that all this would have led to the invention of the bicycle in 1817.

05:48Scientists used preliminary data and climate models

05:52to determine if the eruption of Tambora was the cause of these phenomena.

05:56They compared the data of that year with that of similar years,

06:00and found that the rainfall was about the same,

06:03but that the temperatures were much higher.

06:06By integrating the effects of the volcano in their simulations,

06:09they obtained results corresponding to those of the year without summer.

06:13According to them, such a powerful volcanic eruption

06:16would increase the probability of extreme cooling by up to 100 times.

06:22The explosion of the Toba supervolcano on the island of Sumatra,

06:25which occurred about 74,000 years ago,

06:28represents the largest terrestrial volcanic eruption in the last 28 million years.

06:32Regions of Indonesia, India and the Indian Ocean

06:35were covered by a thick layer of volcanic debris about 15 cm thick.

06:40The eruption caused a volume of rock equivalent to nearly 3 million Empire State Buildings,

06:45and the crater left by this explosion is still visible from space.

06:49The volcanic ashes and gases ejected into the atmosphere partially masked the light of the sun,

06:55triggering a rough volcanic winter that lasted 6 to 10 years.

07:00Some anthropologists establish a link between the eruption of the Toba

07:04and the limited genetic diversity of modern humans.

07:07At this precise time, we can observe a notable demographic decline,

07:11which explains why all modern humans can trace their origins

07:15down to a small group of survivors.

07:17The theory of the Toba disaster suggests that most of the first humans in Europe and Asia

07:23did not survive the climatic upheaval following the eruption.

07:27On the other hand, a more fortunate and genetically identifiable group found refuge in Africa.

07:33However, archaeological and paleoclimatic archives cannot confirm this theory.

07:40Dr. Benjamin Black of Rutgers University and his team

07:44have tried to clarify this paradox

07:46and discovered that we may have studied the climate under the wrong prism.

07:50They carried out 42 simulations of different climatic models,

07:54varying the magnitude of volcanic emissions, the season of the eruption,

07:58the ambient climatic state and the height of the eruption column

08:01in order to determine possible climatic disturbances caused by the eruption of the Toba.

08:06The results showed a significant decrease in temperatures in the northern hemisphere

08:10during the first year following the event, which could reach 10 degrees.

08:14However, the southern hemisphere, where the first humans settled,

08:18did not experience severe cooling, likely to affect them.

08:23The most significant eruptions, capable of seriously altering global climatic models,

08:28come from supervolcanoes such as Yellowstone or Mount Toba.

08:33Fortunately, these eruptions are extremely rare

08:36and only occur once every 100,000 years or more.

08:40However, climatologists study these eruptions to understand

08:44and explain the short cooling periods in the history of our planet.

08:49Every few decades, a volcanic eruption releases a substantial amount of particles and gas.

08:55Some of these eruptions block the light enough

08:58to cause a brief period of global cooling,

09:01felt around the world,

09:03even if this phenomenon does not reach the intensity of a true volcanic winter.

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