Since human civilization began, there have been a number of catastrophic volcanic eruptions
which resulted in the creation of massive calderas and effected the global climate.
One of these occurred at Mount Tambora in 1815, which resulted in the so called year
without a summer.
Another occurred at Santorini, whose eruption in 1610 BC left a massive hole in the island,
and likely gave birth to the myth of Atlantis.
With this being said, there is another volcano with a similarly large eruption in South America
which is largely forgotten about.
The volcano I am referring to is Cerro Blanco in Argentina, which produced a catastrophic
eruption in 2200 BC.
This eruption was one of the largest to occur on the entire planet in the last 10,000 years,
and was the single largest eruption in all of South America during that timespan.
It led to one of the worst droughts on the planet in the last 5,000 years, causing the
fall of the Old Kingdom in Ancient Egypt.
Although this volcano has not erupted since, it will erupt again.
This video will discuss this little known volcano, and mention what its future hazards
are.
The Cerro Blanco volcano can be found in northwest Argentina, where it is very close to the border
with Chile.
As we zoom in on Cerro Blanco, you will note that it does not contain a central tall peak.
Rather, it contains a group of 3 or 4 overlapping calderas, all of which resulted from supermassive
eruptions.
The exact age of Cerro Blanco is unclear, but it appears to have been producing large
eruptions for as many as 6.8 million years.
At least 5 of these eruptions deposited layers of ash dozens of meters thick, representing
eruptions each of which were at a minimum the size of the famous 1883 eruption of Krakatoa.
Each of these massive eruptions would be rated on the volcanic explosivity index as a 6 or
a 7.
I have used a rough estimate to approximate the age of each of these calderas, and the
size of the eruption which formed them.
Within the last 100,000 years, two massive eruptions have occurred.
The older of the two eruptions occurred 72,000 years ago and ejected 43 cubic kilometers
of volcanic rock.
The younger of these eruptions originated from the youngest caldera in the overall complex.
Approximately 4,200 years ago, a large volume of magma intruded into the shallow crust.
Over several years, a massive volume of magma, totaling many billion of tons of molten rock
grew under the volcano.
Then, something triggered a large eruption.
This could have been an earthquake, but it caused this magma to finally travel upwards
and erupt onto the surface.
Soon, a large explosion occurred, as this magma interacted with local groundwater.
From this newly formed crater emerged a plume of ash, which shot 50 kilometers into the
atmosphere.
Pyroclastic flows then raced across the landscape, covering everything within a 35 kilometer
radius with several meters of superheated rock.
These flows may have even traveled up to 100 kilometers away, travelling up tall mountains.
As the sky turned dark, large amounts of ash began falling across a vast area.
Areas within a 200 kilometer radius were hardest hit, as approximately 1 meter of ash fell.
This tall ash cloud quickly was blown to the east, causing several centimeters of ash to
fall across much of what is now Argentina, Uruguay, Paraguay, and Brazil.
Due to the large volume of erupted material, a 6 kilometer wide section of Cerro Blanco
collapsed downwards by 300 meters, forming its newest caldera.
What had just occurred was one of the largest eruptions in human history.
In total, 110 cubic kilometers of ash was ejected, meaning this eruption was rated on
the volcanic explosivity index as a 7.
In the last 10,000 years, only 10 other volcanoes have produced an eruption of this size.
Due to the global cooling caused by this event, a severe dry spell swept around the globe,
causing precipitation to be drastically reduced.
This caused famine around the globe, leading to societal unrest.
Although the existence of Cerro Blanco would not be discovered for several more thousand
years, its eruption led to the collapse of both the Akkadian Empire and the Old Kingdom
in Ancient Egypt.
Since then, only a single eruption has occurred at Cerro Blanco, which formed a large rhyolite
lava dome on its southwestern caldera wall.
I hope that you enjoyed this video!
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