Many large volcanic eruptions are well known, such as the 1980 eruption of Mount Saint Helens
which destroyed part of its summit. In 1991, a different eruption an order of magnitude larger
caused a medium sized volcano to completely collapse. A third eruption in prehistoric times
was 8x the size of the aforementioned eruption of Pinatubo and caused an entire 12,000 foot
tall towering stratovolcano to completely collapse in Oregon. However, within the last 10,000 years,
this was not the largest volcanic eruption on the planet. The volcano which produced
the largest eruption since the end of the last ice age is one few people have heard of,
which is located in Russia. Known as Kurile Lake, it produced a catastrophically large eruption
approximately 8,000 years ago, depositing thick layers of ash more than 1,000 kilometers away.
This video will discuss this little known active volcano, and mention what it’s future hazards are.
The Kurile Lake volcano can be found in the Far East of Russia on the incredibly volcanically
active peninsula of Kamchatka. It is on the southern section of the overall peninsula.
You might be wondering where exactly the Kurile lake volcano is, and why you don’t
see a nearby towering peak. Here’s the thing, the lake IS the volcano. It represents a low
point formed from a massive volcanic collapse which occurred several thousand years ago.
The reason why this volcano exists, along with the other approximately 100 active volcanoes in
Kamchatka relates to a plate collision occurring offshore the peninsula. There, the Okhotsk
tectonic plate is colliding with the Pacific plate. The melted crust from this collision then
migrates upwards before erupting on the surface and forming a chain of volcanoes. However, in the
case of Kurile Lake, the magma did not immediately erupt on the surface. Instead, it built up over
a long time in a massive magma chamber over many thousands of years. During this time, silica from
surrounding bedrock leached into the underlying magma chamber making it more viscous. The first
eruption from this volcano occurred 41,500 years ago, and was truly massive in size. Although we
aren’t truly sure how large the eruption was, it likely was comparable to the 1991 eruption of
Mount Pinatubo. Over the many subsequent thousands of years, the magma chamber which fed this
eruption once again grew in volume. Then, in 7550 BC, a small quantity of magma traveled upwards
towards the surface. When it reached the surface, it erupted in an explosive manner. After a layer
of ash was deposited across the icy landscape, a quantity of rhyolite lava began flowing. This
eventually built a group of several small lava domes. The amount of silica in this lava was a
warning sign of things to come, as the underlying magma chamber was still growing in pressure.
The more silica lava has, the more explosive the resulting eruptions become, as trapped
gasses cannot easily escape from viscous lava. Then, in 6440 BC, something changed. With little
warning, much of the underlying magma chamber shot upwards towards the surface. As the
ground rumbled, a quantity of volcanic gasses began billowing out of cracks in the ground.
Suddenly, the ground exploded upwards. As a large plume of ash shot into the sky,
pyroclastic flows raced across the surrounding landscape. Some of these went across the adjacent
ocean, while others traveled up mountains to the north. Some individual flows were several hundred
meters high and traveled more than 100 kilometers before they stopped. As the eruption continued,
large volumes of ash ejected high into the atmosphere began raining down across much of
Asia. Locations more than 1,500 kilometers away received a coating of ash, while the vicinity
surrounding the immediate eruption received more than 50 meters of superheated rock. Then,
due to the large volume of material erupted, a 14 by 8 kilometer section of land collapsed downwards
to form a caldera. As the ash from the eruption began to clear, a new phase of activity began. In
the center of this caldera, a volume of rhyolite lava began to erupt but was not highly explosive.
Over time, this quantity of lava grew in size to become a large lava dome whose peak is now
found in the center of the overall lake. Finally, the eruption ended. What had just occurred was
the largest eruption on the planet of the last 20,000 years. In total, 155 cubic kilometers
of volcanic rock erupted, and the eruption was assigned a volcanic explosivity index of a 7.
For comparison, this eruption was 155 times larger than the 1980 eruption of Mount Saint Helens.
Since then, no additional volcanic activity has occurred. With this being said, a different
volcano has since grown to the northeast of the overall caldera which is called Ilyinsky.
Although some scientists consider this volcano to be the latest eruptive vent of Kurile Lake,
I disagree due to the differing composition of magma it erupts. I hope that you enjoyed this
video! If you would like to request a specific topic, please leave a comment below. Additionally,
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