They are located in the Highlands of Iceland, north–west of the Veiðivötn and north–east of Landmannalaugar, within the municipality of Rangárþing ytra.

It is part of the Eastern volcanic zone (EVZ).

The craters were formed during a series of eruptions associated with a basaltic dyke intrusion from the volcanic system of Bárðarbunga around the year 877.

[a] These eruptions, like those of the neighbouring Veiðivötn, were from about 65 kilometres (40 mi) (or 42 kilometres (26 mi)[5]) long volcanic fissures within the area of a lake.

The mainly explosive eruptions emitted 5–10 km3 (1.2–2.4 cu mi) of tholeiite basalt.