Just after the new day began on June 30th of 2023, a magnitude 3.3 earthquake struck
underneath a section of Iceland's most dangerous and historically most explosive volcano known
as Katla.
Then in the following 10 minutes, another 8 earthquakes occurred which were volcanic
in origin, occurring in the same section of Katla's large caldera, with one even being
of a larger magnitude.
A true earthquake swarm was underway, causing the ground to repeatedly shake, even involving
one of the largest quakes to strike the volcano in the last 25 years, a magnitude 4.4.
By the time this earthquake sequence had ended, at least 36 detectable earthquakes had occurred,
representing Katla's most significant seismic event since 2016.
Since Katla had been seemingly producing an elevated rate of earthquakes since its last
major swarm on May 4th of 2023, some geothermal data was analyzed.
This found that something unusual was occurring underneath Katla's edifice, as a drainage
of the volcano was found to be producing heightened gas emissions while another site was found
to have water which suddenly contained an increase in electrical conductivity, suggesting
that more abundant geothermal fluids were coming out of Katla's glaciers.
While all of this was occurring, another major piece of Iceland related volcano news largely
went under the radar.
As, a new magmatic intrusion was confirmed to be ongoing underneath a section of the
Reykjanes peninsula.
This magma is believed to have caused several moderate sized earthquake swarms on the Reykjanes
peninsula in the past month.
As, it appears that although this magma is so far remaining within the lower crust, magma
is continuing to pool in it, and this is generating occasional dike and sill magmatic intrusions.
So far, these dikes and sills have not traveled very far, but when they do form, it triggers
heightened seismic activity on the peninsula.
Once these sills or dikes stop, the seismic activity drastically drops.
However, since this magma has remained deep in the crust it has thus far not produced
any drastic uplift centers, so at the present we are unsure exactly where the new intrusion
is centered.
However, in my opinion I have two guesses as to where it might exist based on earthquake
swarms which have repeatedly occurred nearby.
My first guess is a location approximately 1500 meters south of the subglacial mound
known as Keilir.
This location seems to be in about the center of a broad and slow area of uplift on the
Reykjanes peninsula which although it may very well be a false positive aka not a real
signal, was only detected on 3 sensors which are displayed on screen.
The spot south of Keilir would be at the very northeastern end of the dike intusion which
developed in 2021 and 2022, so it would make a lot of sense if this same body of at depth
material was producing another magmatic intrusion.
If this spot was to be the site of the next volcanic eruption on the peninsula, it would
probably produce a repeat of Fagradalsfjall's 2022 eruption, albeit in a new location.
The second possible site of a deep magmatic intrusion is near the northwestern shoreline
of Kleifarvatn Lake.
Since May 27th of 2023, a broad area has been producing an elevated number of earthquakes
via clustered earthquake swarms 5600 meters in length.
This could represent an at depth sill but it is equally as likely to represent stress
released caused by uplift to the west of this region, like witnessed before the eruptions
of Fagradalsfjall occurred in 2021 and 2022.
However, if this region was to produce an eruption, it would be part of the completely
separate Krysuvik volcano which has not erupted since the 14th century.
Regardless, the 8th magmatic intrusion is ongoing on the Reykjanes peninsula.
As for the activity at Katla, while the earthquake swarm could have theoretically been caused
by the intrusion of magma, in my opinion current sensor data does not support this assertion.
Instead, the earthquake swarm was likely caused by increased heat applied to its numerous
fumaroles and hot springs buried beneath the thick ice, which then created an increased
amount of meltwater.
I want to note that these types of earthquakes are more common at Katla during the summer
months.
With this being said, the last time Katla produced elevated geothermal gasses was 7
years ago in 2016.
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!