In the Caribbean, there are 16 active or potentially active volcanoes.
These include Pelee on Martinique, La Soufriere on Saint Vincent, and Morne Watt on Dominica.
However, none of these volcanoes have produced eruptions as large as the topic of this video.
Located adjacent to the town of Soufriere on Saint Lucia are two overlapping calderas
formed by massive eruptions from the Qualibou volcano.
This volcano last erupted in 1766, and today contains the famous Pitons.
This video will discuss this volcano, and mention what its future hazards are.
The Qualibou volcanic complex began formed 400,000 years ago, when a volume of magma
reached the surface.
Initially, the cooled lava which erupted formed a series of small volcanic cones out of a
black colored volcanic rock called basalt.
As time progressed, the rock which was deposited by eruptions became lighter in color, and
deposited andesite instead of basalt.
Over the course of subsequent eruptions, tall volcanic peaks such as Mount Gimie were built
out of siliceous lava.
As lavas continued to become more siliceous, eventually the eruptions stopped.
At depth, a vast magma chamber continued to expand, causing pressure to build.
Then 300,000 years ago, a massive eruption began.
As a plume of ash shot 40 kilometers into the atmosphere, pyroclastic flows raced down
the surrounding jungle and into the ocean.
Then, due to the large volume of lava erupted, a 6 by 8 kilometer section of land collapsed,
forming a large caldera.
The rim of this caldera can still be seen via airplane, as it created a prominent scar
in the landscape.
The eruption which had just taken place was the largest to have occurred within the Caribbean
of the last 1 million years.
In total, 40 cubic kilometers of tephra was ejected, indicating an eruption size 142 times
larger than the 1902 eruption of Mount Pelee.
In the aftermath of this eruption, a series of highly viscous lava domes erupted onto
the surface.
What I am referring to are the famous Pitons, which formed 260,000 years ago.
These lava domes were built out of a gray-white rock type called dacite, and over time formed
a series of prominent cliffs.
Today, these peaks are one of the most distinguishable features on the island of Saint Lucia.
Over the next 224,000 years, other smaller lava domes formed within the Qualibou caldera.
Then, 36,000 years ago, another massive eruption began on the surface.
As pyroclastic flows once again traveled across the landscape, an energetic volcanic rock
called ignimbrite was deposited across much of Saint Lucia.
After this eruption ejected 16 cubic kilometers of tephra, a large patch of ground within
the existing caldera collapsed, forming yet another caldera.
This caldera shares a similar boundary with the prior one, but only measures 3.5 by 5
kilometers in size.
Over the next 20,000 years, intermittent large volume eruptions built a half dozen lava domes
within the area of the recent caldera.
Peaks built during this period include Terre Blanche and Mount Bonin.
15,000 years ago was the last time lava erupted onto the surface in this volcanic complex.
Yet, Qualibou is still considered to be an active volcanic complex.
Why is this the case?
In the west center of the smaller caldera is a series of hot springs and fumaroles which
are referred to as the sulphur springs.
In 1766, the sulphur springs produced a violent explosion which ejected a thin layer of ash
over the southern third of Saint Lucia.
What had just occurred was a phreatic explosion, which marked the latest eruption at this volcanic
complex.
Even today, these vents regularly emit high amounts of volcanic gasses such as sulfur
dioxide and carbon dioxide.
Overall, I consider the odds of this beautiful volcanic complex erupting in the near future
to be quite low, at about 1 in 3500 each year.
If another eruption was to occur, it would most likely take place at the Sulphur springs,
as it represents an area where surrounding groundwater can be heated and potentially
cause another series of explosions.
Such an explosion would create a crater up to 300 meters wide, and throw boulders of
rock within a 5 kilometer radius.
If you were to visit Qualibou, I would not be worried about it erupting during your trip.
I hope that you enjoyed this video!
If you would like to request a specific topic, please leave a comment below!
Additionally, to support this channel, consider becoming a patreon.