The apparent intensity of the eruption has decreased (for now). This morning, roughly 12 hours after its start, only one fissure is still active from the original 3 eruptive fissures last night. Its active part has has shortened and concentrates on a section where a new cinder cone is now being formed. Lava effusion is estimated to be down to approx. 10 cubic meters per second only.
However, this is very likely only a temporary lull in activity; the eruption is still in its very early stage and much more is likely to come. Lava output could resume to increase a lot in a near future. Another, and relatively likely scenario is that new fissures open up, possibly further to the north, as the underground lava intrusion (often called “tunnel” in the Icelandic news) seems to go over approx. 10 km length, stretching all the way to Keilir.
The onset of the eruption in exactly the expected spot
The eruption occurred in exactly the area that was expected by scientists, based on the location of the latest quakes tracing the underground paths of the magma. For this reason, many observers had been waiting in the area north of Fagradalsfjall; among these, Kristín Elísa Guðmundsdóttir, a natural disaster expert at the Icelandic Met Office. She gave an account of observing the beginning of it: at first, air turbulence could be noted as the ground was heated and gasses started to escape. „At 2:25 p.m., we started to see turbulence at Fagradalsfjall and around 4:40 p.m. we could see smoke rising on the northern slopes of Litla-Hrút,“ she says (source: Eruption Begins / RUV.is).
The first fissure that opened was located in a small depression just north of Litli-Hrútun and had a length of approx. 200 m and oriented northeast-southwest. With slight offsets, at least two more fissures in the same line opened shortly after. Low curtains of lava gushed out from these over a length of approx. 900 m and quickly fed lava flows in all directions that burnt and inundated the terrain around the fissures and fed a rapidly advancing, broad flow towards the southeast, that reached 2.5 km length within the first hours.
No infrastructure has so far been threatened although this could of course change if the eruption last long enough to fill the valleys around the fissures and enable the lava to spill over towards the coastal areas both to the south or north, where roads could eventually be cut.
Third eruption in a row
After the eruption in 2021 that lasted 6 months, and the shorter one in summer 2022, which lasted only a few weeks, this is the third eruption in a row on the Reykjanes Peninsula. It came after only 323 days since the last one. All 3 eruptions are close to each other, each representing a rupture along the rift that runs through the peninsula with an offset of a few kilometers, respectively. Scientist believe that a new cycle of frequent rift eruptions has started in 2021, with potentially many eruptions to come in the coming years and decades. This cycle would end a period of approx. 800 repose time since the previous cycle.
Eruption might be much bigger than the previous ones
Magnús Tumi Guðmundsson, professor of geophysics at the Icelandic University, said that the eruption seems to be much bigger, even ten times bigger than the first eruption and possibly three times bigger than eruption in 2022. ”It’s amazing how big the gas plume is from the eruption. It’s many times bigger.“ The magma is probably coming faster and the plume is reminiscent of the eruption in Holurhraun.
Dangerous conditions near the eruption
The main hazard from the eruption are currently the enormous amounts of suffocating gasses being released from the fissures, especially in the early stages of an eruption (as gas typically travels ahead of most of the liquid magma). Therefore, civil authorities have closed the area and urge people to not to approach the eruption from the ground. When the situation stabilizes, viewing areas and access trails will be established.
A second significant hazard is the potential opening of new fissures and the possibility to become trapped between active lava flows when somewhere on the ground near the eruption.