Blog

Knowing the different layers of Earth, we can find out the pattern of convection currents within them. It is obvious within the equatorial plane, because the most regular pattern possible fits exactly into it. Outside the equatorial plane, both centrifugal force and convection paths have to be considered separately. Accordingly, the whole system of convection rolls within the mantle could be analyzed. Knowing the position of convection rolls all over the planet, all the comparison found within this site could be made.

The core of the earth is extremely hot, constantly being heated by radiation. The radioactive material is mainly found within the upper layers, but the mantle must let the heat radiation through all the way down to the core, thereby heating it. The heat is then transferred from core to the bottom of the tectonic plates by convection currents. That is how the Earth works.

Three largest lava flows on Earth during the Holocene period are all originated from a single area in Iceland. First is Thjorsárhraun Lava Field (8,000 years ago), from the Bardarbunga Volcanic System. The magma did flow underground to the Veidivotn area, where the eruption took place. The second was the Eldgjá Lava Field. Then the magma originated from the Katla Volcanic System, forming about 60 km long row of craters. Now it has been found that the eruption took place in 938. Third is the Eldhraun Lava Field from 1783-84. The magma created a dyke from Grímsvötn Volcanic System over to Laki, and then the rift developed to the SW and NE from there.

All the eruptions seemingly started near a major upwelling division line of mantle convection rolls. The same division line takes part in forming the central area of Hveravellir.

The polygons, where the dykes and craters form, are subject to direct pulling effect from the large scale tectonic drift of the North American Tectonic Plate. Rifts open up perpendicularly to the drift direction, forming dykes and craters due to volcanic activity.

This indicates that the upwelling line encountered by the large scale dyke formation, somehow ´ignites´ the approaching magma, leading to eruption.

The Tertiary volcanic formations in Greenland south of Scoresbysund are quite similar to Iceland. Therefore there might be found some similarities. The first to look after are traces of volcanic zones. They might look like this:

This is only based on the presumption that this peninsula was formed under similar circumstances as Iceland.

Some research has been made on the topic: https://jgs.lyellcollection.org/content/154/3/565 , indicating that activity was developing in a rift zone close to the coast, which would then resemble the Icelandic East Volcanic Zone, or even also Öræfajökull Volcanic Belt, replacing the activity of Western Volcanic Zone.

The convection rolls of lower mantle cover 30° from east to west. The Polar and Equatorial parts of the total system intersect each other. The result is that below the 64th parallel, there must be a division within the lower mantle at the depth around 1655 km. The best place on the surface to represent this, is where the two division lines of lower mantle coincide over divergent plate boundaries, namely at the town of Hveragerdi.

On the map, here below, the two division lines between convection rolls have been marked. The blue line shows the lower convection rolls (below 1655 km depth), and the black line shows the upper convection rolls division line (above 1655 km).

This can be difficult to visualize at first. The lower rolls are actually subducted north of 60.3°N. Hveragerdi has also four layers of small scale convection rolls in between 120 and 410 km depth. The combined effect of these division lines creates these special surroundings above.

The spectacular Öræfajökull is found at the 64th parallel, and is by many considered to be located east of the main systems of volcanism in Iceland.

Fjalljökull Glacial Tongue, which slides into the Fjallsárlón Lagoon, shown above, is close to the famous Jökulsárlón, or Glacier Lagoon. These places are found east of the highest volcano in Iceland, Öræfajökull. It is actually responsible for some of the most powerful eruptions in Iceland throughout its written history. So what is the context of this outstanding volcanic site?

The location is shown in context with the central line of Reykjanes Ridge (RR), Reykjanes Oblique Rift Zone (RORZ), South Iceland Seismic Zone (SISZ), and North Volcanic Zone (NVZ). Also, the Borgarfjörður Transverse Fault Zone (BTFZ) is shown, Snæfellsnes Volcanic Belt (SVB), West Volcanic Zone (WVZ), East Volcanic Zone (EVZ), South Iceland Volcanic Belt (SIVB), the volcanically extinct Skagafjörður Volcanic Belt (SKVB), Tjörnes Fracture Zone (TFZ) and Grímsey Oblique Rift (GOR).

The simple extension of these two of the main axis traceble of activity in Iceland, leads to the heighest mountain in Iceland. It is the starting point of Öræfajökull Volcanic Belt, extending between Öræfajökull and the dormant volcano Snæfell in Eastern Iceland. As for the polygon pattern, it closely resembles the names given to the various volcanic and seismic areas in Iceland.

Therefore, when thinking about the edge of the EVZ as the blue, double line of downwelling between different convection rolls, we still have to consider a hidden connection from one corner to the other of the relevant polygons, with a very special volcano, Öræfajökull.