The highly scenic Katmai National Park and Preserve in Alaska has more volcanoes than
any other national park in the entire United States.
Here, there are 13 active volcanoes, including one of the planet's youngest volcanoes that
did not exist before 1912; Novarupta.
It produced the largest eruption of the 20th century, ejecting 31 cubic kilometers of material
and draining the magma chamber of the adjacent Mount Katmai volcano, creating a massive caldera.
However, this steep caldera is not the only scenic caldera within the national park.
To the northeast are the remains of the unusual Kaguyak volcano which contains a caldera with
cliff faces up to 550 meters or 1,800 feet tall.
Although this volcano has not erupted in several thousand years, it is still quite active.
Within its crater lake, volumes of carbon dioxide and other volcanic gasses regularly
bubble to the surface, proving that an at depth magma is still present.
The Kaguyak volcano is located southwest of Anchorage on the Aleutian peninsula, where
the closest major city of King Salmon is 94 miles to the west.
Kaguyak is located in a very volcanically active region, approximately halfway between
the Kukak and Fourpeaked volcanoes.
The most prominent feature of Kaguyak is of course its caldera.
This caldera measures 3 kilometers or 1.86 miles wide and contains two large masses of
material within its lake.
These masses of material are dacite lava domes which formed after the volcano's caldera forming
eruption 5,800 years ago.
Looking at Kaguyak's surrounding edifice with its generally uniform slopes, you might think
that it was once a stratovolcano.
However, this is not the case.
Note how the volcano has two separate high points, with a large low point between them.
If this volcano was to have been a stratovolcano, its caldera rim would have either been a uniform
height or have had one prominent high point.
Instead, Kaguyak is a type of volcano referred to as a lava dome complex.
The two regional high points on its caldera are each large lava domes, which formed rugged
albeit largely rounded domes of material before the volcano largely collapsed.
As a whole, the Kaguyak volcano is composed of 11 lava domes, representing slightly spaced
minor eruptive centers which emplaced lava over a timespan of more than 100,000 years.
The Kaguyak volcano began forming 300,000 years ago when a volume of silica rich magma
intruded into the crust.
Once it reached the surface, it generated a series of powerful explosions, carving out
a several hundred foot wide crater.
From this crater emerged a slow moving viscous lava dome that was gray in color which continued
to grow in size.
This lava dome would continue to erupt for several months at a very low rate, building
a dome shaped edifice.
Between 290,000 and 65,000 years ago, 3 other lava domes formed on the volcano, emplacing
large volumes of ash and material deposited by intermittent pyroclastic flows.
These lava domes had an unusually wide ranging composition, encompassing material from basalt
to rhyolite.
Then, 60,000 years ago, Kaguyak began its most intensive eruptive period.
Over the next 30,000 years the volcano produced 5 additional viscous lava domes.
After this period ended, the volcano began dormant for 24,000 years.
Then, 6,000 years ago, a large lava dome extruded onto the surface in the center of the lava
dome complex.
This acted as a natural plug, which caused an immense amount of pressure to build during
the volcano's next eruption. 200 years later such an eruption came, sending a plume of
ash more than 30 kilometers into the atmosphere.
Part of the voluminous eruption column subsequently collapsed downwards, producing energetic pyroclastic
flows which burned everything in the landscape up to 6 miles away.
Then, due to the large amount of erupted material, a wide swath of the volcano collapsed downwards
like a sinkhole, forming a massive caldera.
In total, 6.5 cubic kilometers of volcanic rock was ejected in an eruption which was
assigned a volcanic explosivity index of a 5.
The two lava domes within the crater lake formed shortly after in 3400 BC.
Although Kaguyak volcano has not erupted in a long time, its next eruption is almost guaranteed
to be highly explosive.
In other words, when it does erupt again, you would not want to be within a 5 mile radius
of its summit.
Thanks for watching!
If you would like to request a specific topic, please leave a comment below.
Additionally, I would like to thank my new patron James T Leamer for supporting this
channel.