During 15-21 October, IMO maintained Aviation Colour Code Orange due to continued activity at Bárdarbunga’s Holuhraun eruptive fissure. Subsidence of the Bárdarbunga Caldera continued at a rate of 30-40 cm per day, concentrated in the NE part of the caldera, and on 15 October was an estimated 0.75 cubic kilometers. On 18 October a M 5.4 earthquake was detected at 0940 in N Bárdarbunga making it one of the biggest earthquakes since the start of the eruption. The lava field continued to grow and the lava production continued at the same rate; the lava field was 60.7 square kilometers on 19 October.

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)