Bjarnarflag is a high temperature area situated west of the Namaskard Pass in the Myvatnssveit County. Eruptions occurred there during the periods between 1725 and 1728, when the Jardbadsholar crater row was created, and between 1975-1984, when the whole area was very tectonically active, and in 1977, a little magma found its way to the surface through one of the boreholes. Potatoes were cultivated in the warm soil from the year 1930. This endeavour had to be abandoned soon because of parasites.

In 1939 a factory house was build to process sulphur. It burned down before work started in the sulphur mines. In 1968, a few boreholes were sunk there to supply steam for a 2,265 MW power station. Both the electricity and the steam were used to manufacture diatomite in one of the most hideous factory ever built in this country.

During the most resent tectonic period, fissures created there swallowed the winter supplies of raw materials of the factory and damaged its houses severely. The earthquakes also damaged the boreholes and diminished their capacity considerably, and fissures cut the roads.