On April 11th, 2022, a swarm of earthquakes began underneath the prominent Fuji like Mount
Edgecumbe stratovolcano in far eastern Alaska.
Although the largest of these earthquakes which occurred before the swarm ended was
a mere magnitude 2.8, these quakes were not tectonic in origin.
Rather, they occurred due to a new intrusion of magma underneath the Mount Edgecumbe volcanic
complex.
It is now nearly 11 months later and this magmatic intrusion is still ongoing.
We now know several facts such as the depth the magma is pooling at, how much magma is
present, and where on the volcano would be the most likely site for an eruption to begin
if an eruption did eventually end up occurring.
However, in the past 6 months there was an additional development at the often snow covered
and scenic Edgecumbe volcano.
On the eastern section of Kruzof Island, within three quarters of a mile of the trail which
leads to Edgecumbe, a pond was spotted that was suspiciously bubbling and appeared to
be emitting a gas of some kind.
While this vent might not be new as it simply might have been unnoticed until now, paraphrasing
a sentence from an article by James Brooks at the Alaska Beacon, "a local couple discovered
a possible new gas vent at Edgecumbe in October 2022".
If this vent is new, measuring the amount of gasses it is emitting might provide a helpful
tool for analyzing the nature of the ongoing magmatic intrusion as it has not yet been
measured yet.
Based on oral histories of indigenous peoples, Edgecumbe has not erupted in at least approximately
800 years.
It has not produced a known magmatic intrusion since then, so what is ongoing could be truly
described as unusual.
The magmatic intrusion had surprisingly been ongoing for 40 months beginning in August
of 2018 before it was first detected in April of 2022.
This uplift is centered around the summit of Mount Edgecumbe, meaning that if an eruption
was to eventually occur, its summit crater represents the most likely spot an eruption
would begin at.
Since 2018, the ground has been pushed upwards at a maximum rate of 8.7 centimeters or 3.4
inches a year which is quite significant for a volcano in this area of Alaska.
This occurred due to a deflating body of magma at 20 kilometers depth supplying magma to
a region beneath the volcano at 10 kilometers depth where it is currently pooling.
Of course, there is a possibility that magma has reached shallower than 10 kilometers depth
but this has not yet been proven, despite the fact that the intrusion is still ongoing.
Also, the amount of magma in this intrusion is more than 0.1 cubic kilometers of material
but less than 1 cubic kilometer of material, meaning that during a worst case scenario
if all of this magma erupted explosively, it could create an eruption registering in
on the volcanic explosivity index scale as a 4, being perhaps as much as 5 times larger
than what Mount Redoubt produced during its 1989 to 1990 eruption.
As a whole, Mount Edgecumbe is somewhat similar to the El Chichon volcano in Mexico or the
Mount Parker volcano in the Philippines.
What I mean by this is that like the other two volcanoes, during the last 20,000 years
it has erupted at a rate of less than once every 500 years on average yet when it has
erupted during the last 20,000 years has often produced a VEI 4 or larger explosive eruption.
Although Mount Edgecumbe's next eruption could be quite small aka perhaps a VEI 1 or 2, there
is also a decent change of it being around a VEI 4, causing heavy regional ashfall and
pyroclastic flows on Kruzof Island.
For example, two of Mount Edgecumbe's eruptions which occurred 13,054 and 14,536 years ago
respectively produced a little more than 5.3 and a little more than 3.6 times the volume
of tephra the 1980 eruption of Mount Saint Helens produced.
With all of this being said, there is some good news for the citizens of Sitka.
Not only is the Edgecumbe volcano an island away, but the vast majority of times a magmatic
intrusion at a volcano does not end up reaching the surface and producing an eruption.
Thus, the volcano is more likely to not erupt than erupt based on its current level of activity,
although this could change with new developments.
As a result, I have placed Mount Edgecumbe on my opinion based 0 to 10 volcanic unrest
scale to show the intensity of unrest it is experiencing as a 4.
Thanks for watching!
If you would like to request a specific topic, please leave a comment below.
Additionally, I would like to thank this channel's patrons on Patreon and channel members on
YouTube!