The volcanic eruption in Geldingadalir/Fagradalsfjall ended in late September 2021, after some six months of lively activity. Occurring rather close to towns, roads and powerlines, this dying out of the earthly fire was a relief to people. The ensuing months have been rather quiet in the 30 volcanic fissure/fault systems in Iceland, except for earthquakes underneath some of the large, central volcanoes, as well as tectonic earthquakes in some of the systems, plus a stressing bout of volcano-tectonic unrest close to and beneath Mt Fagradalsfjall. It contained and was partly caused by, an injection of magma into the crust. The event started on 21. December and lasted approx. to 7. January. The origin of the magma was in the Fagradalsfjall deep-seated magma reservoir. The magma volume is estimated at 18 million cubic metres. The magma almost surfaced, causing an eruption, but was luckily halted at a depth of only 1.5 kilometres. Small and medium-magnitude earthquakes numbered approx. 20,000.
At least six large, central volcanoes currently show signs of unrest; some have stirred for many years: Askja in the northeast plus Bárðarbunga and Grímsvötn in the Vatnajökull Ice Cap, Öræfajökull (Iceland´s glaciated, and highest mountain) as well as Katla (subglacial), both in the south and finally Hekla (Iceland´s marker volcano) also in the south. Earthquakes, inflation, gas release and new high-temperature geothermal fields are the most prominent signs. Not knowing details of preludes to eruptions from most of these volcanoes, forecasts are not readily available. However, all the volcanoes are well monitored.
Text by: Ari Trausti Guðmundsson, Geologist and Author
