One of the largest explosion craters on the planet formed on March 1st, 1954.
A 15 megaton high yield nuclear weapon was detonated on Bikini Atoll, vaporizing everything
in a large radius and leaving behind a large crater.
This crater measured 6,510 feet wide and 250 feet deep.
However, despite its large size, this was far from the largest explosion crater on the
planet.
The single largest explosion crater did no form through warfare or weapons testing, but
rather through a natural geologic process.
In the remote western section of Alaska ia an approximately 17,000 year old massive explosion
crater, which formed as the result of a volcanic eruption.
Known as Devil Mountain Lake, it measures 3.7 miles wide, 5 miles long, and 328 feet
deep.
This video will discuss this large explosion crater, and mention the future hazards of
its associated volcanic field.
The Devil Mountain Lake is located in far western Alaska, in the sparsely populated
Seward Peninsula.
The city of Teller is located 95 miles to the southwest.
First, some context.
The Devil Mountain Lake is considered to be a volcanic explosion crater, known as a "maar".
Maars form when the heat from a volume of rising magma interacts with abundant groundwater
or ice near the surface.
This interaction causes the water to flash to steam.
Since steam takes up far more space than water or ice, it causes an immense amount of pressure
to build.
Eventually, the pressure becomes too great, and the ground explodes upwards in what is
termed a phreatic eruption.
This large maar is only a small part of the much larger Espenberg volcanic field.
It contains about a dozen young vents which include 5 small shield like volcanoes, several
cinder cones, and 5 large maar explosion craters.
These maar explosion craters are the largest examples of this volcanic feature on the planet.
Maars are a relatively common type of volcanic feature, often forming a crater between 300
and 3,000 feet wide.
Some maars are a bit larger, such as the 1 mile wide hole in the ground in Oregon.
However, it is difficult for a maar to get any larger.
With the amount of energy required to form a maar more than a mile wide, typically the
lava ends up reaching the surface, producing a sustained explosive eruption rather than
a single explosion crater.
So, why are the Espenberg Maars unusually large, each measuring more than 2 miles wide?
The answer is the climate they are located in.
From satellite, you can easily see the sparse vegetation present in the landscape these
craters are located in.
The biome is tundra, which contains a thick layer of permafrost.
This tundra, and the thick glacial ice cover at the time of these maar forming eruptions
are the cause of their unusually large sizes.
The high amount of water content greatly amplified the explosive eruptions which occurred, causing
them to stretch farther out and be larger than if these explosions instead occurred
in a desert.
In this section of Alaska, intermittent volcanic activity has been ongoing for more than 28
million years, mostly at an active volcanic field to the south known as Imuruk Lake which
contains a large lava flow visible from satellite.
The Espenberg maars were preceded by a series of several small shield volcano forming eruptions
approximately 200,000 years ago.
These eruptions produced several hundred foot high volcanic cones and mile long lava flows.
Then, volcanic activity switched to maar forming eruptions.
The first maar to form in this field was the White Fish Maar, which originated 160,000
years ago.
The North Killeak maar formed next, 125,000 years ago.
The South Killeak Maar formed 40,000 years ago.
The most recent and largest maar to form, Devil Mountain Lake, originated 17,500 years
ago.
Its eruption was so large that it sent pyroclastic flows up to 17 miles away.
Anything within 12 miles of the eruption was covered by more than 4 feet of volcanic rock
and ash.
Today, you can still find the remains of the 6 cubic kilometers of ash from this eruption
scattered in the barren landscape.
Based on the long history of this volcanic field, it will erupt again.
However, its eruptions are infrequent and no one lives in the area, as they occur about
once every 40,000 years.
I hope that you enjoyed this video.
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