In 2018, an intense series of earthquakes were felt on the island of Mayotte.
This island is located between the northern coastlines of Mozambique and Madagascar.
It contains an active volcano which has erupted 3 times in the last 10,000 years.
Clearly, a new eruption was occurring, yet there was no signs of an eruption on the island
while intense earthquakes continued.
One of the generated earthquakes was quite large, measuring at 5.8 on the Richter scale.
Soon, local fishermen reported a “burnt tire smell” and large groups of dead fishes.
A submarine volcanic eruption was ongoing.
It was only later that the true scope of the eruption which had just occurred was realized.
In the span of only a few months, a new volcano, measuring 820 meters or 2,690 feet tall had
been constructed.
Beforehand, the ground was flat and simply part of the ocean floor.
It takes most volcanoes thousands or tens of thousands of years to create the towering
edifice this volcano created in only a few months.
So, how did this occur?
Where is the new volcano?
This video will discuss this fascinating feature, which represents only the latest eruption
of the massive Mayotte island shield volcano.
The newly formed volcano can be found be found 50 kilometers east of the easternmost point
on Mayotte island.
This 5 kilometer wide newly formed volcanic edifice originated at a deep point in the
ocean, as it was constructed beginning at 3,500 meters or 11,482 feet below sea level.
So, how did this massive eruption occur?
The answer is that this eruption represented a caldera collapse.
To the east of the island, the first series of earthquakes occurred in the shape of a
ring, representing a previously unknown caldera.
These earthquakes in May of 2018 were caused by movement of magma in the underlying deep
magma chamber, due to a new large volume of molten rock seeping into the volcano.
Eventually, the large volume of magma went to the east as it represented a path of least
resistance, causing additional earthquakes as it moved through the crust.
After 2 months of movement, the large volume of molten rock has traveled a total of 70
kilometers vertically, and was now just below the ocean floor.
Suddenly, a series of lengthy fissures opened on the ocean floor, and output a submarine
river of lava.
It output a spectacular 200 cubic meters of lava per second, which is more than triple
that of the ongoing eruption of La Palma in the Canary Islands.
In only 11 hours, a 100 meter high edifice had already been constructed, and the volcano
continued to grow.
By a week later, the new volcano was 250 meters in height.
Over the next several months, the new shield volcano continued to grow at an impressive
rate.
However, all of this newly erupted magma had drained the underlying magma chamber.
This caused the ancient 10 kilometer wide caldera to begin subsiding deeper into the
ocean, thus creating a submarine caldera collapse.
During this timespan, a large volume of volcanic gasses were released from both the deep caldera
on the ocean floor and a fault line directly connected to the magma chamber to the east
of Mayotte’s capital city.
By the time the output of lava ended, a total of 5 cubic kilometers of rock had been emplaced
on the ocean floor.
This eruption was truly spectacular and quite unusual, as it was the first to occur from
the island’s massive volcano in more than 4,000 years.
For comparison, this eruption was more than triple the size of the massive 2012 eruption
of the Havre Seamount in New Zealand, which was until now the largest known submarine
eruption.
For a context of this in comparison to a land volcano consider this.
One of the most active volcanoes on the planet, Kilauea in Hawaii, had one of its most energetic
and long lasting eruptions which lasted from 1983 to 2018.
This eruption output 3.3 cubic kilometers of lava, which is what the Mayotte submarine
eruption produced in merely a few months.
With all of this being said, the new shallow magma has potential implications for the island
of Mayotte which warrant further study.
Since molten rock is now in the caldera’s magma chamber, it could unexpectedly intrude
into one of the faults which dissect the caldera, thus creating a new eruption in a potentially
populated area.
The densely populated island of Pamanzi is now at greater risk of a future volcanic eruption.
After all, this island was the site of Mayotte’s last land eruption, which explosively formed
the Dziani Dzaha explosion crater in 2,050 BC.
It takes an impressive amount of energy to form a 1050 meter wide and 1200 meter long
explosion crater.
I hope that you enjoyed this video.
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