Glacier Hofsjokull (The Temple Glacier; 1760m) is a round icecap in the centre of the country.  It is the third largest glacier of Iceland with an area of about 900 kmē.  The thorough research of the landscape underneath the ice revealed a great mountain massif of a central volcano with a vast, ice filled caldera with an area of 70-80 kmē.  Its size is similar to the caldera, Askja, of the mountain massif Dyngjufjoll.  The Hofsjokull caldera is 600-700 m deep and the glacier tongue Blondujokull flows through its pass toward west.  Nothing is known about Holocene eruptions, but they are considered possible.  Further research of the ice cores of the Greenland Glacier and cores from the ocean bottom around the country will bring us new facts about this central volcano.

The Energy Authority of Iceland launched a geological research and mapping of the discharge areas of Rivers Blanda, Jokulsa East and West to the north of the glacier and prior to that the geologist Gudmundur Kjartansson collected geological data around it and was the first to map such results.  The most prominent, small lava fields around the glacier are Lambahraun (craters under the ice), a lava field near Mt Illvidrahnukar, Haolduhraun (craters under the ice) and Illahraun, which is the largest one with its crater row near Brattalda.  All these lava fields are of the thoelite basaltic type.  No chronological determinations are available for those lava fields yet.  Geothermal activity has not been spotted and earthquakes are rare in this area, but the central volcano is considered active.