On August 24th of 2022, a volcano within Alaska which had not shown any signs of life for
48 years began producing a cluster of deep earthquakes.
Over the next 4 days, the earthquakes got progressively shallower and shallower, suggesting
that a new batch of magma had intruded underneath the Trident volcano.
Then, on August 29th, the depth of the quakes once again got dramatically shallower, jumping
from 14 kilometers or 9 miles in depth to 5 kilometers or 3 miles depth.
However, after more than 100 earthquakes occurred, the earthquake swarm seemingly subsided after
September 2nd.
This trend was then suddenly reversed on September 22nd, as at least 40 earthquakes struck in
close proximity to one another, suggesting that whatever magma or magmatic fluids were
causing this volcanic unrest was still on the move.
As a result of all of this activity, the alert level of the Trident volcano was raised from
green to yellow on September 29th.
Although I have been unable to independently verify the following statement, satellite
data seems to suggest that a ridge to the south of the Trident volcano is being slowly
uplifted due to a presumable intrusion of magma into the crust.
Thus, it rightfully appears that the massive Katmai National Park and Preserve has its
best chance to produce a volcanic eruption since the Fourpeaked volcano erupted in 2006.
For context, the Trident volcano is located in southwest Alaska where it is 275 miles
southwest of the city of Anchorage.
Trident is a fairly remote volcano, as the closest population center is 52 miles away
on the distant Kodiak Island.
Despite being fairly remote, it is located within a busy air route meaning that any future
eruption could theoretically disrupt air traffic across much of the state.
Trident is located in a highly volcanically active area, with 3 other active volcanoes
within a 6 mile radius, one of which produced the largest explosive volcanic eruption of
the 20th century.
Like the other 12 volcanoes in Katmai National Park, Trident exists due to the offshore collision
of two tectonic plates.
There, the Pacific Plate is subducting underneath the North American Plate.
The melted material from this collision then migrates upwards, until it erupts onto the
surface, forming a chain of volcanoes.
The Trident volcano contains four partially overlapping volcanic cones, the oldest of
which began forming around 150,000 years ago.
Since historical record keeping began, all of Trident's eruptions have originated at
its southwestern peak.
Consisting of 15 volcanic eruptions in the 20th century, 14 of which occurred between
1949 and 1974, these eruptions emplaced blocky flows of primarily andesite lava which flowed
up to 2.8 miles distant.
While the explosiveness of Trident's eruptions has widely varied, its eruptions have consistently
had an explosive component, generally rating on the volcanic explosivity index as a 2 or
a 3.
This means that if this volcano was to erupt, you would most likely want to view the eruption
if you were nearby from several miles away at a minimum, as this volcano has produced
pyroclastic flows.
In terms of the latest activity, the Alaska Volcano Observatory stated that the ongoing
earthquakes were either occurring due to the movement of magma or magmatic fluids.
I agree with the former explanation, as the progression of the earthquakes from the suspected
crust-mantle boundary to less than 10 miles deep honestly looked like a textbook example
of a magmatic intrusion, much like I observed before the 2021 eruption of La Palma in the
Canary Islands.
Of course, the earthquakes might not be occurring due to magma, but it honestly is by far the
most likely explanation.
The unconfirmed uplift seems to support this hypothesis, and if I had to speculate where
magma was right now I would suggest between 3 and 9 miles below the volcano.
If an intrusion was to be confirmed, Trident would have a low double digit percentage chance
of producing a new eruption.
Of course, most magmatic intrusions do not result in a volcanic eruption, but regardless
the ongoing activity is quite interesting.
Thanks for watching!
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