The nation of Iceland is truly a land of volcanoes, as its landmass contains more than two dozen
active volcanoes, and is almost completely comprised of volcanic rock.
Although volcanoes on the mainland which have produced large volume explosive eruptions
such as Katla, or recent effusive eruptions such as Krysuvik tend to get the most attention,
there are other interesting volcanic systems nearby.
One of these volcanoes is referred to as Eldfell, which produced an infamous volcanic eruption
on a densely populated island off the southern coast of mainland Iceland in 1973.
Its eruption formed a brand new cinder cone, and although destructive, successful countermeasures
were employed to divert the flows of lava it produced.
The Eldfell volcanic cone is located 113 kilometers southeast of Reykjavik on the island of Heimaey.
It represents the youngest volcanic vent on an island which formed through the combination
of a half dozen separate vents.
However, these vents merely represent one island of a much larger volcanic system, called
Vestmannaeyjar.
Vestmannaeyjar consists of islands such as Heimaey, Surtsey, Hellisey, and a half dozen
submarine vents.
These vents are spread out along a northeast trend of activity, which represents an area
called the eastern volcanic zone.
Here, the Eurasian plate is spreading apart from the North American plate.
This allows for shallow molten rock in the mantle to intrude into a series of faults
and fissures in the crust, eventually erupting onto the surface.
The island of Heimaey began forming a mere 13,000 years ago, when a volume of basaltic
magma erupted onto the seafloor at shallow depths of 76 meters or 250 feet.
Although some explosive activity occurred due to the interaction of lava with seawater,
this was kept to a minimum due to water pressure at those depths.
Over the span of 180 days, half a cubic kilometer of molten rock was erupted.
This brought the summit of the volcano to just 10 meters beneath the surface.
Then, in 8050 BC, another eruption occurred.
Due to the shallow depths this occurred at, magma interacted with seawater, which flashed
it to steam and generated a series of white and black colored explosions.
These explosions occurred in what is termed a "surtseyan" style eruption, ejecting fragments
of rock and ash which eventually formed a small volcanic plateau above sea level.
By the time the eruption had ended, a several hundred meter wide tuff ring has been constructed,
much like seen at Hunga Tonga Hunga Ha'apai before the island exploded.
500 years later, another less explosive eruption occurred to the east, which built a secondary
volcanic island.
This island contained an ever growing cinder cone which produced beautiful fountains of
lava.
Eventually, these two islands merged.
In 4550 BC, a new eruption began 4.5 kilometers to the south, which once again formed another
volcanic island.
It also produced a large tuff ring, whose central crater was eventually smoothed out.
In 4270 BC, an explosive eruption formed a brittle island out of ash, but its center
eventually exploded, creating a 1 kilometer wide crater.
In 3950 BC, the island's most voluminous eruption built a 227 meter or 745 foot tall cinder
cone known as Helgafell.
Its lava flows greatly expanded the overall volcanic edifice, connecting what were two
separate islands.
99% of the island's population lives on land built by this eruption.
After a series of earthquakes on the island began in mid January of 1973, the island's
most famous eruption began on January 23rd when a fissure opened up on the northeastern
section of the island.
Initial activity occurred along the entirety of the fissure, producing fountains of lava,
but by 8 hours later almost the entirety of erupted rock was funneled into a single volcanic
cone.
This cone just happened to be on the eastern edge of the town, which had 5,300 residents.
As strombolian volcanic activity continued, lava flows expanded in all directions, covering
hundreds of homes.
To prevent the entire town from being wiped out, a novel idea was applied.
The residents pumped seawater in long hoses from the ocean onto the lava flows, in an
attempt to cool the advancing flows.
This was surprisingly effective, as the outer edge of flows acted as a natural barrier since
it was cooler, which diverted molten rock away from the town.
By the time the eruption ended 5 months and 5 days later, 2.2 square kilometers of land
had been added to the island and a new 200 meter tall volcanic cone had been constructed.
It is quite likely that it will be another 500 to 1500 years before another volcanic
eruption occurs on this island, so the residents who live there should not be too worried about
a repeat of Eldfell in their lifetimes.
Regardless, in the unlikely event a new eruption was to occur, I recommend that the entire
island be evacuated.
The chance of another 1 kilometer wide explosion crater forming underneath the town exists
during a future eruption, if enough nearby groundwater or seawater was present at the
time.
I hope that you enjoyed this video!
If you would like to request a specific topic, please leave a comment below!
Additionally, I would like to thank my new patron Joe Schmuckatelli for supporting this
channel.