It is now day 2 of Iceland’s brand-new volcanic eruption, which is only a 45-minute drive
out of the nation's capital city, Reykjavik, followed by a medium distance hike.
The good news is that the eruption site is now officially open to tourists, which are
recommended to follow the 7.9 kilometer or 4.9 mile long one way walking path which I
have marked on screen.
This is different than the walking path utilized during the prior two eruptions, which involved
a path towards the west rather than east of the lava flows.
In the last 24 hours, the eruption has continued at a high rate, although a decrease in eruptive
intensity occurred in the hours after the eruption began as shown by the level of recently
measured volcanic tremor.
The amount of volcanic tremor has recently stabilized, reflecting views seen by those
who have been actively watching the eruption.
While this in of itself could suggest a fairly brief eruption, it is also quite typical for
effusive eruptions to decrease in intensity with the first hour being the most intense
and the 24th hour being less intense.
The first 24 hours of Fagradalsfjall’s ongoing eruption saw a third fissure I estimated to
be 600 meters in length temporarily form, erupt, and then seemingly cease its activity.
This suggests that we might already be at the stage of the eruption where some vents
are becoming dominant over others.
Because of this change in eruptive intensity, in my opinion I suggest that the current eruption
does seem more consistent with data witnessed in the 2022’s several week rather than 2021’s
several month-long eruption from the same volcano.
Although, the truth is it’s too early to be sure.
Of course, volcanoes are complex and I’m only comparing behavior with the two prior
eruptions, making it a very limited dataset-based opinion.
While the initial eruptive rate probably peaked at around 60 cubic meters per second, I now
estimate the eruptive rate has dropped as of day 2 to be half that, aka 30 cubic meters
per second.
Although this is not an official estimate, I estimate that lava flows now cover 1.4 square
kilometers, an increase of 0.68 square kilometers from hour 4 of the eruption.
While the now 2 currently erupting fissures could still expand, you might notice that
several small spatter cones have already formed and continue to grow on sections of the combined
1100 meter long fissure.
What I predict to be the dominant future spatter cone is located about halfway up the longer
850 meter long fissure, which seems to currently be 11 meters or 33 feet in height.
The erupted lava is now flowing at a fairly slow rate to the southeast, although sections
of it are heading southwest along a small valley bordered by subglacial volcanic ridges
formed during the last ice age.
While 60 cubic meters per second represents the highest eruptive rate among Fagradalsfjall’s
2021, 2022, and 2023 eruptions, this figure is quite small when comparing to other primarily
effusive to moderately explosive eruption’s in Iceland’s past.
For example, the initial mildly explosive portion of the 2010 Eyjafjallajökull eruption
erupted lava at a rate of 50 cubic meters per second while the 2014 eruption of Bárðarbunga
erupted lava at a peak rate of 800 cubic meters per second.
But, this does not compare to the 7,000 cubic meters per second the peak of Grimsvotn’s
1783 to 1784 Laki eruption produced, where a 27 kilometer long fissure was involved.
In other words, while the ongoing eruption of Fagradalsfjall whose outline is shown on
screen is seemingly intense, this seems quite small compared to prior eruptions.
The Reykjanes peninsula in my opinion has not recently produced any effusive eruptions
involving high hundreds or even thousands of cubic meters of lava each second.
With this being said, there is still a respectable 3,000 meter or 9,842 foot long dike at magma
supplying the ongoing eruption.
And, there is still a possibility that more sections of this fissure could erupt as far
north as a few hundred meters southwest of Keilir.
Thanks for watching.
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