Esjufjöll

The subglacial Esjufjöll volcano at the SE part of the Vatnajökull icecap, north of Öraefajökull volcano, consists of the Snaehetta central volcano and a large caldera. Most of the volcano, including the 40 km caldera, is covered by the icecap, but parts of the SE flank are exposed in NW-SE-trending ridges. Most of the exposed rocks are mildly alkaline basalts, but small amounts of rhyolitic rocks are also present. A large jökulhlaup that came down the Jokulsa a Breidamerkursandi along the coast SE of Vatnajökull in the beginning of September 1927 was accompanied by a sulfur stench, and on one occasion, ash fall on the Breidamerkurjökull considered to have possibly originated from Esjufjöll. Although Holocene eruptions have not been confirmed from Esjufjöll, earthquake swarms that could indicate magma movements were detected in October 2002, and recently in October 2010.