BackgroundThe Thordarhyrna (Þórðarhyrna) central volcano has been moderately active during the past 10,000 years. It is the second and less active central volcano of the Grímsvötn-Laki volcanic system, located about 20 km SW of the more active Grímsvötn central volcano and connected to it by a subglacial mountain ridge.
The volcano has a diameter of 15 km, and is covered by ice 100-600 m thick within the Vatnajökull glacier. The last eruption occurred in 1903 CE. The recent activity has been explosive (phreatomagmatic) basaltic eruptions with tephra volumes ranging from 0.01-1 km3, but several rhyolitic nunataks characterize this volcano. Eruptions are accompanied by jökulhlaups (glacial floods). Being the only second central volcano on a volcanic system with considerable historical volcanic activity, Þórðarhyrna is treated as an independent volcano although the fissure swarm events are shared with the Grímsvötn system.
See also: Sentinel hub | Landsat 8 | NASA FIRMS