It is now day 13 of Iceland's latest eruption of the Reykjanes volcano. Nearly at the two
week mark, we are truly appearing to see the beginning of the end of this unusual
eruption. While on March 20th there were 9 active vents erupting lava,
this figure decreased to 7 on the 23rd, and today this figure is now only 3 vents.
These three vents have formed spatter cones, which have grown to 10 meters or 32.8 feet,
3 meters or 9.8 feet, and 2 meters or 6.6 feet in height respectively. All three are erupting lava,
but only the northernmost most active vent is producing lava fountains that regularly reach
above the 50 foot mark. This vent is for all intents and purposes now the dominant vent,
and will likely be the last vent standing when the declining activity at vents 2 and 3 finally
ceases. Eruptive activity since the latter half of March 25th has somewhat stabilized,
but is also producing intermittent decreases and increases in activity. I personally estimate that
no more than 9.5 cubic meters per second of molten rock is actively erupting at the present. Despite
a slowly dying eruption, molten rock has still continued to flow into new areas, including parts
of two kipukas. Kipukas are isolated patches of terrain that are typically although not always
raised above the surrounding landscape which are surrounded on all sides by young lava flows. While
a smaller kipuka with an area of 500 square meters existed 3 days ago it has since been completely
covered by fresh lava. Another larger kipuka in the same timespan has since been reduced to
one third its original size. This area will likely be completely filled within the next 4 to 5 days.
Lava is only flowing towards the south and southwest, and in the last 72 hours has covered an
additional 0.32 square kilometers, with new areas being shaded in red. The main expansion occurred
at the Melhóls mine, which is now completely covered in molten rock and is thus unusable.
In total, lava has so far covered 6.18 square kilometers or 2.39 square miles in a grand total
of 27.9 million cubic meters of molten rock. So, where exactly does this volume rank
amongst other eruptions with large effusive components which had a low silica content?
In the context of recent Reykjanes peninsula eruptions since 2021, it ranks in as the second
largest. However, if we expand and look at other eruptions in the rest of Iceland,
27.9 million cubic meters is quite small. In fact, this figure is 896 times smaller
than the largest effusive eruption to occur in Iceland since the end of the last ice age! While
it is larger than 1 of Nyiragongo's 3 recent flank eruptions, it is still smaller than all 3 of Mauna
Loa's recent eruptions. In a world context, the current eruption is indeed quite small.
Footage circulating online shows workers using bulldozers to scrape fresh lava that
overtopped a 4 meter high lava wall which I have geolocated to this segment in yellow. This dirt
barrier is going to be thickened and increased in height by another 5 to 6 meters to prevent any
molten rock from spilling over into Grindavik. Although lava effusion rates are continuing to
decrease alongside volcanic gas emissions, sulfur dioxide has still proven to be an
intermittent issue in recent days. Air quality sensors in Hafnir at one
point measured sulfur dioxide gas emissions at a concentration of 7000 micrograms per cubic meter.
For reference, 2620.3 micrograms per cubic meter of sulfur dioxide is equal to 1 part per million
of sulfur dioxide in the air. Exposure to greater than 2 parts per million of sulfur dioxide is
considered unsafe, meaning that outdoor activity had to be halted at Hafnir until the gas emissions
eventually dissipated at that village. As a final note, I would like to thank
this channel's patrons on Patreon and channel members on YouTube!