Report on Krysuvik-Trolladyngja (Iceland) — 13 October-19 October 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
13 October-19 October 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Krysuvik-Trolladyngja (Iceland). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 13 October-19 October 2021. Smithsonian Institution and US Geological Survey.
63.917°N, 22.067°W; summit elev. 360 m
All times are local (unless otherwise noted)
Icelandic Meteorological Office (IMO) reported that during 18 September-18 October no lava effusion was detected at the Krýsuvík-Trölladyngja volcanic system. The seismic swarm that had begun on 26 September in an area SW of Keilir (about 10 km NE of the fifth vent), at the N end of the dike intrusion, had significantly decreased in mid-October. The Aviation Color Code was lowered to Yellow (the second lowest level on a four-color scale) on 18 October. IMO noted that gas emissions were ongoing, though with very low concentrations of eruptive gases. Minor thermal anomalies were detected less often; incandescence from previously emplaced lava flows was occasionally visible at night. IMO also stated that residual heat, gases, and incandescence may continue for weeks to months.
Geological Summary. The Krýsuvík-Trölladyngja volcanic system is described by the Catalogue of Icelandic Volcanoes as an approximately 50-km-long composite fissure swarm trending about N38°E, including a 30-km-long swarm of fissures, with no central volcano. It is one of the volcanic systems arranged en-echelon along the Reykjanes Peninsula west of Kleifarvatn lake. The Fagradalsfjall and Krýsuvík fissure swarms are considered splits or secondary swarms of the Krýsuvík–Trölladyngja volcanic system. Small shield volcanoes have produced a large portion of the erupted volume within the system. Several eruptions have taken place since the settlement of Iceland, including the eruption of a large basaltic lava flow from the Ogmundargigar crater row around the 12th century. The latest eruption, identified through tephrochronology, took place during the 14th century.