On July 30th of 2022, an earthquake swarm began at two distant volcanoes located on
islands in the Atlantic Ocean.
The first swarm began at the Krysuvik volcanic system in Iceland, where a series of more
than 5,500 earthquakes including a magnitude 5.4 quake occurred directly or indirectly
due to a fresh intrusion of magma at depth.
Due to this major story, another volcano which also produced seismic unrest largely went
under the radar.
In the Azores, the Terceira volcano also produced a minor earthquake swarm on July 30th, with
its largest earthquake registering in as a magnitude 2.7.
Due to this quake occurring alongside a number of smaller magnitude quakes, and the fact
that this area tends to have very little seismicity, the alert level of the Terceira volcano was
subsequently raised from V0 to V2.
For context, the volcano alert level system in the Azores ranges from V0 to V6.
Anything above V0 is considered abnormal, while V5 and V6 are reserved only for actively
erupting volcanoes.
While this indicates something unusual is ongoing at this volcano, I want to remind
my viewers that the Sao Jorge volcano is also still producing occasional earthquakes while
being at an alert level one tier higher, V3.
So, is an eruption likely?
What is the context of these earthquakes?
This video will answer these two questions and discuss what might happen next at this
volcano.
For some context, the island of Terceira is located 1550 kilometers west of mainland Portugal.
The exact reason why this or any other volcano in the Azores island chain exists is surprisingly
still up for debate, but has to do in part with the following.
To the west of the island of Terceira is the intersection of 3 tectonic plates.
Here, the African Plate, North American Plate, and Eurasian Plate are spreading apart via
a mid ocean ridge in what is known as a triple junction.
This interaction has created a series of large fault lines and ridges which go outwards from
these plate boundaries in a perpendicular direction.
One of these ridges goes through the island of Terceira, where magma intrudes into the
crust through a fissure system, eventually erupting via a path of least resistance.
This fissure system happens to cut through the island's youngest volcano, Santa Barbara,
which has been erupting intermittently for 29,000 years.
While this specific stratovolcano hasn't specifically produced an eruption since 1400 CE, the fissure
system which runs through it has erupted 3 times since then.
The most recent eruption on land occurred in 1761, creating a series of lava flows east
of Santa Barbara.
And, two more recent eruptions occurred along the fissure from submarine vents just offshore
the island, the last of which occurred from 1998 to 2000.
The recent earthquakes are quite interesting since they are also occurring alongside and
adjacent to this ridge.
Thus, there is a possibility that they are related to the movement of magma or hydrothermal
fluids underneath the volcano.
However, the fissures also represent a lengthy series of large fault lines, so the earthquakes
could be completely tectonic in origin.
I personally checked for signs of magmatic uplift and found none, but the satellites
I used only carried data up until July 26th, before the earthquake swarm began.
Since it is uncertain, what I am about to say is speculation.
Due to the low magnitude of the quakes, and specific depth they occurred at, I believe
they are not magmatic but rather are occurring due to the movement of hydrothermal fluids.
These fluids move whenever they are heated to a higher than normal temperature or a change
occurs in the overall volcano.
Eventually the expansion becomes too great that it causes a fault to rupture, triggering
an earthquake.
Based on the current nature of this swarm, it does not implicate that a volcanic eruption
is about to occur, although this could change over the next several days to weeks depending
on how this situation develops.
Thanks for watching!
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