Háskóli Íslands

Katla volcano

GPS coordinates: 63°38'0" N, 19°3'0" W
Max elevation:~1500 m.a.s.l.

The Katla subglacial volcano is a part of the Katla volcanic system, located on the propagating Eastern Volcanic Zone in south Iceland. The volcanic system is ~80 km long and comprises a central volcano with a caldera (600-750 m deep, encircling ~100 km2), and a fissure swarm. It is the fourth most active volcanic system in Iceland, after Grímsvötn, Bárdarbunga and Hekla but in terms of erupted volume of magma it is the country’s largest producer in historical time, having produced ~25 km3 (total DRE) in ~20 eruptions after ~870 AD. The central volcano is covered by the Mýrdalsjökull ice-cap and Katla eruptions are often accompanied by large jökulhlaups. Katla eruptive products are mainly basaltic but a subordinate volume of felsic magma has been erupted. Three types of volcanism are known from the system: (1) explosive hydromagmatic basaltic eruptions and (2) silicic explosive eruptions, both taking place on subglacial volcanic fissures, and (3) predominantly effusive basaltic eruptions, occurring out along the fissure swarm. The explosive basaltic volcanism is by far the most common one and during the Holocene over 300 such eruptions have taken place. The explosive silicic eruptions occurred during prehistoric time, but during the period ~5500 BC-400 AD at least 12 such eruptions are known. The effusive basaltic eruptions are the least common type of volcanism but have produced vast lava flows (e.g. the ~18 km3 Eldgjá eruption, 934-940 AD).
Historical eruption record: 1918, 1860, 1823, 1755, 1721, 1660, 1625, 1612, 1580, 1500,15th century, 1440, 1416, 1357, 1262, 1245, 1179, 12th century, 934/938, 920, 9th century. The last eruption that broke through the ice-cap was in 1918 but in 1955 and 1999 small jökulhlaups were detected on Sólheimasandur, possibly caused by subglacial eruptions at Katla.

Compiled by Bergrún A. Óladóttir, 28.01.2011

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