What you are looking at is one of the most scenic regions of the planet.
Here, in the Kuril islands, there are numerous jagged peaks, and more importantly abundant
volcanoes.
Some of these volcanoes in the last 10,000 years produced some of the planet's largest
recent explosive eruptions.
One of these massive recent eruptions occurred on Onekotan Island.
This massive eruption left behind a 7.5 kilometer wide deep caldera which is now filled with
a crater lake.
Within this crater lake is the Tao Rusyr caldera's youngest volcanic cone, which beautifully
jets out of the water to a height of 1,272 meters or 4,173 feet.
This volcano last produced an eruption in 1952 and will certainly erupt again.
The Tao Rusyr caldera is located on a chain of islands between southern Kamchatka in Russia
and northern Japan, where it is closer to Kamchatka.
Tao Rusyr is one of two large caldera complexes on the island it is situated on, called Onekotan;
the other is the also active Nemo volcano to the north.
In addition, this island contains remnants of what is likely two older extinct volcanoes,
which form high points inbetween the two large active peaks.
Approximately 200 kilometers east of the island, the Pacific tectonic plate is subducting underneath
the Eurasian plate.
The melted material from this collision then migrates upwards, until it erupts on the surface,
thus forming a chain of volcanoes which includes Tao Rusyr.
Due to the fractional crystallization of basaltic oceanic crust, when magma initially erupted
onto the surface it had a basaltic to andesitic composition.
As this magma interacted with shallow groundwater and surface ice since a small patch of land
was already present at the eruption site, it caused the material to flash to steam and
explode, generating a powerful series of volcanic explosions.
This left behind a several hundred meter wide crater from which viscous lava erupted, slowly
building a basaltic andesite lava dome.
Due to this region being understudied, we are unsure exactly when this first series
of eruptions occurred.
However, based on comparing the modern volcano to the ages of similar volcanoes in the region,
the overall volcano is likely 60,000 years.
Over a period of tens of thousands of years, a west to east dike trend developed underneath
the volcano, causing several vents to form along a chain of activity.
After numerous vulcanian eruptions which ejected bombs of lava and produced pyroclastic flows,
the volcano had been built to a height of more than 500 meters.
Then, something peculiar occurred which caused new lobes of andesite lava to be unevenly
distributed to the west more often than the east.
This suggests a breached summit crater, which largely funneled andesite lava in predominantly
one direction.
During the most recent glacial maximum 20,000 years ago, a thick series of glaciers expanded
across the towering stratovolcano, carving thick cirques and glacial valleys in the landscape.
These glaciers later melted away, causing a sudden release in pressure on the volcano.
By 5550 BC, a large magma chamber had grown underneath the existing stratovolcano which
had a summit at approximately 1,500 meters above sea level.
Something subsequently caused a large batch of the existing magma to rush towards the
surface, triggering one of the planet's largest recent explosive eruptions.
After a series of powerful explosions occurred, a continuous plume of ash shot high into the
atmosphere, reaching a height of more than 40 kilometers.
Part of this eruption column then collapsed downwards, producing several hundred meter
tall pyroclastic flows which raced across the landscape.
These pyroclastic flows may have travelled as much as 50 kilometers before stopping,
wiping out all plant and animal life on the island.
As a several meter thick layer of ash continued to pile up, the underlying magma chamber was
beginning to show signs of structural instability.
A large portion of it had been drained by the eruption, which soon triggered a large
section of overlying rock to collapse downwards by more than 800 meters, forming a massive
caldera.
The eruption which had just occurred released 60 cubic kilometers of tephra, and was assigned
a volcanic explosivity index of a 6.
In the several thousand years following this collapse, a new andesitic stratovolcano called
Krenitsyn grew out of the caldera via numerous lobes of overlapping andesite lava flows.
Much of this volcano was built in merely a five thousand year long timespan, although
this island within an island is still quite active.
In 1952, a new explosion blasted out a 300 meter wide crater on the volcano's eastern
slope.
Over the next 7 days, a dome of andesite lava erupted, filling this crater with a mass of
gray volcanic rock.
Since then, no additional volcanic eruptions have occurred.
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