Of the more than 1,000 active volcanoes around the planet, only 9 have earned the designation
of a supervolcano.
These supervolcanoes can be found across several continents and include Yellowstone in Wyoming,
Campi Flegrei in Italy, and Aso in Japan.
Among these supervolcanoes, only one is located in Central America.
The supervolcano I am referring to is Atitlan, which is located in Guatemala.
It is still quite active as its magma chamber has produced explosive eruptions as recently
as 1856.
The Atitlan supervolcano is located in south central Guatemala, where it is 70 kilometers
west of the nation's capital, Guatemala City.
As we zoom in on this supervolcano, you will note that it contain a vast lake, which appears
to be rather circular.
This lake fills the low points of the majority of the volcano's youngest caldera, which originated
approximately 85,000 years ago.
That eruption distributed ash over an area of 6 million square kilometers or 2.3 million
square miles, ranging from Florida to Ecuador.
Yet, this eruption merely represented the smallest of 3 caldera forming eruptions.
The largest of Atitlan's calderas is 37 kilometers long and 20 kilometers wide, which formed
in an eruption an order of magnitude larger.
The Atitlan stratovolcano began forming 14 million years ago, when a volume of andesite
lava erupted onto the surface.
This initial phase of activity began constructing a volcanic cone which was covered in layers
of gray ash.
Explosive eruptions occurred, building this individual volcanic cone into a towering stratovolcano.
Over the next several million years, groups of stratovolcanoes and smaller volcanic cones
were constructed.
Over time, eruptions from these vents became increasingly explosive.
The reason for this is that the lava was slowly becoming more silica rich as it leached material
from the underlying crust.
This caused erupted lava to have a higher viscosity, which began constructing lava domes
instead of volcanic cones.
Then, a long term period of dormancy occurred.
Underneath the volcanic complex, a large amount of molten rock slowly built in the underlying
magma chamber.
Then, 11 million years ago, something caused this highly siliceous magma to finally erupt.
As several large vents erupted simultaneously, kilometer high pyroclastic flows raced across
the landscape, even travelling up mountains.
The furthest away these flows reached was 115 kilometers distant at the modern town
of Cuilco.
As ash began raining down, it quickly piled up.
Within a span of 48 hours, some areas had been buried in more than 200 meters of volcanic
rock.
Then, due to the large amount of volcanic material erupted, totaling 2800 cubic kilometers
of molten rock, a massive section of land collapsed downwards, forming a truly impressive
caldera.
In the following 3 million years, a similar sequence of events occurred.
A basaltic stratovolcano eventually became andesitic, followed by lava dome forming eruptions
and then finally a period of dormancy.
By 8 million years ago, the center of the volcanic complex had moved 5 kilometers to
the south of its original location.
Then, it had another massive eruption.
Pyroclastic flows once again swept across the landscape, and a total of 450 cubic kilometers
of ash and lava was ejected in another supereruption.
Then, for an unknown reason, the overall volcano became dormant.
Activity would not resume until 1.8 million years ago, when the aforementioned cycle began
again.
This cycle culminated in a catastrophic eruption 85,000 years ago, which formed the modern
22 kilometer wide caldera.
In total, 270 cubic kilometers of ash was ejected.
Remnants of this eruption can be found in the several dozen meter thick beds of ash
found in the surrounding landscape such as shown on screen.
In the aftermath of this eruption, a new volcanic cone known as San Pedro erupted from a vent
on the southwestern caldera wall.
Over the next 45,000 years, a 1400 meter or 4700 foot tall stratovolcano was formed.
After this stopped erupting 40,000 years ago, a new stratovolcano known as Toliman began
to form.
This cone stopped erupting 10,000 years ago and activity has since been confined to the
Atitlan volcanic cone, which completely formed in the last several thousand years.
Since 1469, this volcano has produced 14 medium sized explosive eruptions.
Although an eruption has not occurred since 1856, it will erupt again in the future.
Such a future eruption would require the complete evacuation of several towns surrounding this
volcano in a 10 kilometer radius due to the risk of pyroclastic flows.
I hope that you enjoyed this video!
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