The 2021 eruption of La Soufriere on the island of Saint Vincent has brought significant attention
to the threat posed by the more than a dozen active volcanoes spread across the Caribbean.
Due to great forecasting and public adherence to warnings, no one died in this devastating
eruption.
With this being said, there is another potentially dangerous volcano, which many in the area
have largely forgotten about.
Located in the northern Caribbean is a group of two islands which are municipalities of
the Netherlands.
Both of these islands contain active volcanoes, which could pose a threat to nearby populations
in the future.
The lesser known of these two volcanoes is located on the island of Saba.
This volcano, also known as Mount Scenery, encompasses the entire 5 kilometer wide island
it is situated on.
It last erupted in 1640, and will certainly erupt again.
This video will discuss this volcano and mention what its future hazards are.
From satellite, the nature of this volcano is quite obvious.
The island of Saba primarily consists of a group of overlapping lava domes formed by
the eruption of viscous lava, much like seen in the first phase of the aforementioned La
Soufriere eruption.
These domes are today the site of several villages, and collectively form rather steep
cliffs which made early attempts of ships to land on the island quite difficult.
However, these lava domes merely represent the top half of the overall volcano.
The other half is located below sea level.
Saba began forming approximately 400,000 years ago, when a volume of andesite lava erupted
onto the ocean floor, at a depth of about 650 meters.
After approximately 50,000 years of intermittent eruptions, this primarily submarine volcano
was just below the ocean surface.
Then, after a series of explosions occurred, the first section of Saba climbed above sea
level.
At the time, the island merely contained a single central lava dome and a grouping of
nearby ash.
This first lava dome has since eroded away into the sea, as it used to be located at
Torren's point on the northwest section of the island.
Eventually, eruptive activity shifted towards what is now the center of Saba.
Additional lava domes were constructed, some of which overlapped each other.
During these eruptions, lava domes would on occasion partially collapse, creating pyroclastic
flows.
In-between these lava dome forming pelean style eruptions, a few larger explosive eruptions
occurred.
These deposited layers of dacite ash around the island, representing less frequent sub-plinian
eruptions with sustained eruption columns.
Then, 100,000 years ago, a large section of Saba collapsed to the southwest.
This was likely associated with one of the aforementioned sub-plinian eruptions which
erupted dacite, but this is not a certainty.
Today, you can still see the scar left by this ancient collapse.
Since this collapse, the central lava dome known as Mount Scenery was built via intermittent
eruptions, which filled much of the collapse scar.
One of these eruptions produced a 2 kilometer long andesite lava flow, which today is the
site of the island's airport.
The exact size of the eruption in 1640 is unclear, but it was likely relatively small.
I interpret it to be a small phreatic eruption centered near where the village known as "The
Bottom" is today, as it overlies a thin layer of ash deposited by short distance pyroclastic
flows.
Overall, this volcano is quite unusual for the Caribbean in that it is one of the longest
lived volcanoes in the region.
For most of its long history, Saba has consistently produced infrequent eruptions, perhaps 1 eruption
every 5,000 to 10,000 years.
Thus, it will likely be some time before the next eruption at Saba occurs.
However, when the next eruption does occur, the entire island would be rendered uninhabitable.
Due to the small edifice of the island, bombs of lava and pyroclastic flows would easily
reach the entire landmass.
Using the US Geological Survey method of rating volcanoes, Saba would be classified on the
upper end of the moderate threat category.
I hope that you enjoyed this video!
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