On July 30th, 2022, a swarm of earthquakes began striking the Reykjanes peninsula in
Iceland just northeast of where the Geldingadalir volcano famously erupted from March to September
of 2021.
This began at around 12:17 pm local time, creating a cluster of quakes which were largely
at 7 kilometers depth.
Over the next 24 hours, earthquakes seemingly got shallower and shallower, suggesting that
their origin was due to the movement of magma at depth.
As of the writing of this video, more than 3,600 quakes have occurred due to an intrusion
which is likely at a depth of 4 to 7 kilometers.
As a result, the alert level of the Krysuvik volcanic system which Geldingadalir is a part
of was raised from green to yellow.
A new volcanic eruption appears possible in the next several days to months which would
most likely begin at the GPS coordinates shown on screen.
Of course, the current magmatic intrusion is merely suspected but not specifically confirmed
as of yet.
And, even if it was to be confirmed, the vast majority of magmatic intrusions never reach
the surface.
Since 2020, the Reykjanes peninsula has been the site of 6 potentially now 7 separate magmatic
intrusions, of which only 1 resulted in a volcanic eruption.
To give you a context of why so much volcanic activity is occurring on the peninsula, we
first need to understand that Iceland as a whole is almost completely volcanic in origin.
Volcanism is so common in Iceland because the nation sits right over a mantle hotspot
just like the Hawaiian island chain does and also sits atop a plate boundary which is spreading
apart.
This spreading creates faults and fissures in the crust which act as a path of least
resistance for magma which intrudes into them.
The Reykjanes peninsula represents one spot where the rifting is occurring, resulting
in the creation of 4 volcanic fields which trend in a southwest to northeast direction.
These volcanoes consist of a series of low prominence cinder cones, spatter cones, and
fissure vents which form along this trend in an unusual type of volcano referred to
as a "crater row".
Although the exact reason why the following occurs is unknown, the Reykjanes peninsula
seems to produce numerous clusters of volcanic eruptions in a brief timespan before becoming
relatively dormant for several hundred to thousand years.
The last cluster of eruptions lasted from 875 to 1341, and consisted of 21 volcanic
eruptions from 3 of its volcanoes.
Normally, a timespan of the same length on the peninsula would only produce 2 volcanic
eruptions.
Scientists think that the peninsula is currently undergoing a similar intense eruptive period,
meaning that more volcanic eruptions are a near certainty in the next several decades
to centuries.
Although a fresh magmatic intrusion has yet to be confirmed, there is a significant amount
of evidence in addition to the ongoing quake swarm which suggests that one is ongoing.
For one, the harmonic tremor monitored at seismic stations adjacent to the earthquake
swarm spiked in intensity twice; a smaller increase occurred on July 26th and a more
intense one occurred on July 30th.
Additionally, there appears to be an increased release of gas from Geldingadalir's fumaroles
during the last 48 hours.
This is supported by satellite data which also detected thermal signatures, suggesting
a potential spike in temperature from these fumaroles beginning on July 30th.
While the magnitude 5.4 earthquake which occurred on July 31st wasn't a magmatic earthquake,
its occurrence hints at the movement of magma at depth.
When magma intrudes into the crust, it often pushes up overlying ground.
This subsequently causes increased stress to build on preexisting fault lines which
then occasionally rupture, generating an earthquake, which is what was suspected to have created
this large quake.
If a new volcanic eruption was to occur, it would be similar in nature to Geldingadalir's
2021 eruption, consisting of the creation of a series of spatter cones and slow moving
lava flows.
Although it could have an initial explosive phase due to the interaction of magma with
groundwater and ice, this is not a certainty.
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