Due to the ongoing eruption of La Palma in the Canary Islands, a number of my viewers
have grown concerned about a group of equally active volcanic islands, the Azores.
These islands contain a total of 11 active volcanoes, which have produced a number of
highly explosive eruptions in the last several thousand years.
A number of these volcanoes are still quite visibly active, such as the Furnas volcano
with its numerous fumaroles venting volcanic gasses.
However, this volcano does not represent the site of the most recent volcanic eruption
in the island chain.
For that, we need to travel further west.
There, on the island of Fayal, a volcanic eruption occurred from 1957 to 1958, which
constructed a new island that eventually joined with the main island's western peninsula.
Although this volcano has not erupted since, it will erupt again.
This video will discuss this volcano and mention what its future hazards are.
The Azores island chain exists at an unusual area of the Earth's crust.
They are emplaced across the boundaries of three tectonic plates near what is termed
a triple junction.
In the mantle, underlying these 3 plates is a hotspot termed the Azores hotspot, which
intermittently supplies molten rock to the surface.
The Fayal volcano began forming around 900,000 years ago, when a large volume of magma erupted
onto the ocean floor.
Over the next several tens of thousands of years, continued submarine volcanic eruptions
built a towering stratovolcano.
Eventually, the volcanic cone broke the ocean surface, forming the beginnings of the northeastern
and eastern edge of the modern island.
After a long period of dormancy, construction of the island's main stratocone began 450,000
years ago.
Its eruptions initially started just below the ocean's surface, but soon climbed above
it and erupted large volumes of gray ash and andesite lava.
Due to underlying fissures in the crust, eruptions were a combination of explosive and effusive.
Effusive or mildly explosive eruptions occurred along large east to west trending faults,
which acted as a path of least resistance for molten material.
On the other hand, eruptions at or neat the summit of Fayal were vulcanian in nature,
producing intermittent large explosions associated with pyroclastic flows.
These explosive eruptions built the central peak to a height of more than 500 meters.
Eruptive activity later moved to the southeast, forming a series of cinder cones and tuff
rings such as this feature off of the island's southeastern coastline.
In the last 16,000 years, the Fayal volcano has produced 14 distinct eruptions.
Before this latest eruptive phase began, the western peninsula of the island did not exist,
as the western coastline was the red line marked on screen.
After several thousand years of renewed activity, the summit of Fayal stood at 1400 meters above
sea level.
Then, in 980 AD, a massive eruption occurred.
What started as a series of phreatomagmatic explosions soon escalated into a major explosive
eruption, generating a 14 kilometer high column of ash.
Pyroclastic flows subsequently raced across the overall island, originating from Fayal's
summit.
Then, due to the large amount of erupted rock, the center of the volcano collapsed downwards,
forming a 400 meter deep and 2 kilometer wide caldera, which is today called Caldeira.
In the aftermath of this caldera collapse, subsequent eruptions solely occurred along
a western chain of activity.
These eruptions all produced extensive lava flows which originated from cinder cones,
such as the 1672 to 1673 eruption shown here.
Overall activity continued to migrate westwards, producing a new cinder cone in 1957, which
rose off Fayal's western coastline.
After a year of activity, this vent termed Capelinhos merged with the overall island.
A small lava flow even erupted within Caldeira in the later stage of the eruption.
Many residents of Fayal still remember this eruption as it caused the destruction of 300
homes.
When Fayal erupts again, the entire island could be put at risk.
If an eruption begins in Caldeira, the entire island would need to be evacuated due to the
risk of fresh lava forming a plug which could subsequently explode.
However, the next eruption will most likely form a new cinder cone on the western peninsula
of the island, requiring only a regional evacuation.
The odds of a future eruption are about 1 in 1,000 each year.
I hope that you enjoyed this video.
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