During 22-28 October, IMO maintained Aviation Colour Code Orange due to continued activity at Bárdarbunga’s Holuhraun eruptive fissure. The eruption was confined to the main vent, Baugur Crater, which had reached 80 m high on 24 October. Subsidence of the Bárdarbunga Caldera continued; during an overflight on 24 October volcanologists noted that the depression in the caldera was 40 m. A report on 27 October noted that geothermal heat was increasing, and a cauldron in the SE corner of Bárdarbunga had deepened by 25 m over the previous month, thought to be linked to the caldera subsidence. In addition, the lava field covered 64.6 square kilometers.

Geological Summary. The large central volcano of Bárðarbunga lies beneath the NW part of the Vatnajökull icecap, NW of Grímsvötn volcano, and contains a subglacial 700-m-deep caldera. Related fissure systems include the Veidivötn and Trollagigar fissures, which extend about 100 km SW to near Torfajökull volcano and 50 km NE to near Askja volcano, respectively. Voluminous fissure eruptions, including one at Thjorsarhraun, which produced the largest known Holocene lava flow on Earth with a volume of more than 21 km3, have occurred throughout the Holocene into historical time from the Veidivötn fissure system. The last major eruption of Veidivötn, in 1477, also produced a large tephra deposit. The subglacial Loki-Fögrufjöll volcanic system to the SW is also part of the Bárðarbunga volcanic system and contains two subglacial ridges extending from the largely subglacial Hamarinn central volcano; the Loki ridge trends to the NE and the Fögrufjöll ridge to the SW. Jökulhlaups (glacier-outburst floods) from eruptions at Bárðarbunga potentially affect drainages in all directions.

Source: Icelandic Meteorological Office (IMO)