Krýsuvík
The Krýsuvík area reaches the geothermal areas of Austurengi, Krýsuvík, Köldunámar, Trölladyngja and the area around Sandfell. The first four areas are continuous as shown by electrical resistance measurements, but the Sandfell area is not. The main area isa circular area, around 50km2 in diameter within a 10 ohm line. The Sandfells area is measured in the same way and is about four km2. Sveiflaháls and Vesturháls along with Trölladyngja are palagonites made up put of many lava eruptions and are mostly 300-400 meters in height.

Modern lava covers plains west of the ridges and between them. Their source is lava crevices from both sides and are outside the Vesturháls and Trölladyngja. Lava crevices are also east of Sveifluháls and explosion fissures are west of it, but there is little lave. The lava activity decreases from there to the northeast where there is a depression where Kleifarvatn can be found. Geologicalformations between Sveifluhás and Austurengja are older than west of the ridges and in the lava areas. There is quite alot of tuff formation from another volcano eruption chain which is east of Kleifarvatn. Hot spring activity in above mentioned four geothermal areas are very different.

Sandfell
The geothermal heat of Sandfell is in a lava flow northeast under the mountain; there faint steam vapours rise up in some places. In one area there is a claybased transformation in the earth where the heat has measured being near boiling point. Hyaloclastite in Vesturháls is very transformed close to Sandfell and around Selvellir, and there are slopes with lakes flowing beneath. Above the ridges across the steam near Sandfell there is a large leirgulahveraskell but cold. The area could be larger than it appears on the surface. The temperature drops in the boreholes after a few hundred meters, which beckons the question about there the rising current of air comes from. Drilling in Trölladyngja indicates that it can be found under Sogar. In Krýsuvík it would probably found under Sveifluháls. The Austurengi geothermal heat is on the outskirts of the geothermal heat system according the resistance measurements, just like in Trölladyngja holes westward.

In the area where the resistance measurements are detected do not need to be described because of currents methods resistance cannot be detected around and above 240°C. Seltún in Krýsuvík is where the hot springs are most continuous in Hveradalir and near Seltún and along the ridges, and steam and clay springs. There are also quite a bit of sulfur springs and a lot of earthen plaster precipitation. The hot springs are also in Grænavatn. From Grænavatn to Gestsstaðir lake there lie erupted volcano crevices with more craters to the north, with more in Hveradalir and near the springs near Seltún. The highest temperature in the boreholes in Hveradalir is around 230 °C. The deepest drilling reached down to 1200 meters. The heat is near boiling point at a depth around of 300 meters, but cools down lowered down. However, there are measurements below 4oo meters.

Austurengjar
In Austurengjar the geothermal heat is mostly in strips which lie from Austurengir springs north of Kleifarvatn. A lot of transformation can be seen in rocks in immense area from both sides. Not only is there geothermal heat in this area but in these heat strips there are quite a few exploded craters that have erupted cinder and some lava. The largest strip is around 100 meters in diameters, northeast of Stóra Lambafell and a lot of cinder east of it. These craters are fairly young. One 600 meter deep borehole is near Kleifarvatn, about 150 meters west of the hot spring strip. The highest temperature in it is around 160 °C.

Late in summer of 1924 the Austurengja hotsprings, which were not very powerful then, awoke due an earthquake. There are large, but older, hot spring crates north of it, which indicates that the geothermal heat is near boiling point like in Krýsuvík. There is a place called Köldunámar west in Sveifluháls, way north from the geothermal heat in Krýsuvík. Not far in the west there is lava formation and some sulfur (Leynihver), but in the slope there is a cold geothermal skella. Earthen plaster can be seen which indicates that at some period of time there would have been sulfur springs.

Brennisteinsfjöll
The geothermal area in the Brennisteins mountains are 40-500 meters above the sea level. The active geothermal heat can be seen by the steam which is at a height of 450 meters, however a cold transformation is in four places, indicating that there was more activity some time before. The geothermal heat on the surface is insignificant and compared to the distribution of the geothermal heat and transformation the area is around 3 square kilometers. Resistance measurements indicate that the area is about 18 square kilometers at a 700 meters below sea level, and about 1200 meters below geothermal heat is detected. The geothermal area in the

Brennisteins mountains lies in a continuous crater area, where there have been at least 3o to 40 eruptions since the ice age. The fractures are very young in the area near the sea, and north of Mosfellsheiði there often earthquakes in a five kilometer wide and 40 kilometer long belt. Earthquakes in Brennisteins mountains can become quite arge. The main types of earth layers are tuff and crater stations which have risen above glaciers and lava has flowed and become table moutains or lava formations. All rock formations are basaltic and not intermediate silica or acidic rocks have been found on the surface.

Sources from the Orkustofnun.