Antarctica is known for its harsh cold climate, friendly penguins, and vast ice covered landscape.
Yet, unknown to many, this giant continent also contains several active volcanoes. One
of these volcanoes towers to 3,794 meters above sea level, and is erupting right now. The volcano
I am referring to is called Mount Erebus, which is the highest active volcano on the continent.
At its summit, Erebus contains an active lava lake, which occasionally erupts bombs of lava.
This video will discuss this volcano, and mention what its future hazards are.
Mount Erebus is located in about 3900 kilometers south of the town of Christchurch within
Antarctica. This towering volcano is located only 37 kilometers north of McMurdo station,
both of which are on Ross Island. Ross Island was formed by 4 different
volcanoes over the course of the last several million years. The only volcano
of these to still be active is Mount Erebus. Mount Erebus began forming 1.3 million years ago,
when an unusual type of lava reached the surface to the west of Mount Terra Nova. When this lava
cooled, it had a black color but also contained numerous crystals of gray feldspar. This unusual
rock type was called phonolite, and indicated that Mount Erebus was being fed by a deep magma
chamber due to an underlying hot spot in the earth's mantle. Over the next several hundred
thousand years, large flows of lava traveled more than a dozen kilometers, constructing
a large shield volcano. However, eventually the style of eruption became slightly more explosive,
resulting in a change in the topography of Erebus. New eruptions now intermittently ejected bombs of
lava and small volumes of ash in what is termed a strombolian eruption. Over time, these eruptions
increased the overall slope of Erebus, as the volcano transition to a stratovolcano.
I want to note that at 2500 meters in elevation, the volcano contains a large circular impression.
In my opinion, this largely hidden feature is likely the result of a
catastrophic caldera collapse, which probably occurred around 350,000 years ago. However,
this is purely speculation, as we have not dated the rocks which form the apparent caldera rim.
By 80,000 years ago, Erebus was 3500 meters tall. Then, a massive eruption suddenly occurred. As 58
cubic kilometers of ash was ejected high into the atmosphere, a 5 kilometer wide section
of the volcano collapsed, forming a prominent caldera rim at about 3200 meters in elevation.
In the aftermath of this eruption, a dozen different vents erupted large volumes of lava
which built this volcano back to its pre collapse height. Then, 18,000 years ago, another caldera
collapse occurred. This eruption was smaller in size than the previous caldera collapse,
but still resulted in the formation of a 3 kilometer wide summit caldera.
Since this caldera collapse, eruptions have been far less
energetic and remained confined to within the inner caldera rim.
Since 1900, Mount Erebus has erupted 14 times. The most recent of these eruptions
began in December of 1972, and continues to the present day. At the main crater of the volcano,
a lava lake intermittently erupts in a strombolian manner. Every time the volcano produces a small
explosion, it ejects bombs of large feldspar crystals called anorthite. These crystals are
encased in a thin layer of obsidian, which then quickly erodes away. This results in a scattered
assortment of large feldspar crystals around the volcano which are thus named Erebus crystals.
Another interesting feature of this remote volcano can be found on its flanks.
When fumaroles exist is cold climates, they can form what are called ice towers. Mount Erebus
contains dozens of these beautiful features, some of which are more than 10 meters tall.
Although Mount Erebus is located rather close to McMurdo, its history of primarily small eruptions
mean that the outpost is not in any immediate danger. Using the US geological survey method
of rating volcanoes, Mount Erebus would be classified as a low threat volcano.
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