Author: Steingrimur Thorbjarnarson

The Icelandic Plateau is elliptical and can be drawn accurately with a definite central point. Expanding the ellipse towards the Jan Mayen Fracture Zones, it overlaps them. Expanding further, an ellipse with same NS-axis meets with the West Coast of both Norway and Greenland. The same structure shows consistency with Greenland-Iceland Ridge and Iceland Faroe Ridge. To describe the details accurately would take many pages, but everyone can have a short look at this map, saying as much as thousand words:

Of course this is no coincidence, because of the large scale convection rolls found underneath the North Atlantic Ocean. The main division line between those convection rolls is found near, and parallel to, the central axis of the Reykjanes Ridge. The fact that Ægir Ridge became inactive, leaving a slice of East Greenland where Jan Mayen is found today, did lead to the special result that the West Coast of Norway and West Coast of Greenland match within this framework. The symmetry found along certain latitudes is due to the effect of Earth’s rotation, and the correspondatly regular formation of mantle convection rolls.

As some aspects can be seen clearer in context with the convection rolls model, another map is added hear with similar information:

Along 64°N, the most obvious symmetry is the 60° interval between West Greenland and West Norway, with central point exactly where the two convection rolls division line passes through Iceland. The other central focus of Iceland is where the two ridges would meet if they were continued on the surface. That is the central point of the Large Icelandic Plateau, and also the central point for an elliptical form that fits with Jan Mayen Fracture Zone, and thereby the end point of the Kolbeinsey Ridge (KR). It also marks the end of the Ægir Ridge. Large scale polygons seem to be affecting the locations of termination of all the ridges.

The location and alignment of the Reykjanes Ridge is consistent with both older and newer volcanic areas of Iceland. It can be shown that five parallel areas of volcanic activity have developed durning the last 24 million years. Moreover, they follow the model of convection rolls closely:

The timing is marked in the map according to this table:

The table is from https://orkustofnun.is/gogn/Greinar-starfsmanna/Arni-Hjartarson-2003-PhD-heil.pdf

This regularity forms a base for us for realizing the real nature of what we call ‘rift jump’. Also, it shows that the convection rolls under the country marked with wide red lines are quite dominant when it comes to volcanic activity and rift process. Nature is not simple, so the other layers underneath also affect the surface. Therefore, to fully analyze the formation of Reykjanes Ridge, the related volcanic zones and volcanic belts, the whole pattern of convection rolls has to be taken into account. Remember that the wide, red lines are upwelling lines. In between, there is one line (thinner) that is downwelling. Thereby you can visualize the scope of each convection roll extending NE-SW (at 120 km depth). When more familiar with the system, you can also visualize the lower layers with additional convection rolls.

The rift zone ´jumps´ in Iceland are well known, occurring every 7 million years or so. The central axis of these zones have been mapped, and the regularity of interval between them can be detected easily. One volcanic zone has hitherto not been included, because it is not a rift zone. All the same, it fits into the pattern of regularity. The wide red lines are upwelling division lines between uppermost convection rolls. These rolls interact with the tectonic plate at the depth of 120 km.

The NW rift axis and the Snæfellsnes-Húnaflói rift axis are extinct, but Reykjanes Ridge and the Eastern rift axis are active. Öræfajökull is found on the fifth line.

The basic map is found in: https://www.semanticscholar.org/paper/The-Skagafj%C3%B6r%C3%B0ur-Volcanic-Zone-An-ephemeral-Rift-Hjartarson/3e8f5295fd6fe47e9f336c53d285fd76f44904ee

For the last centuries, all volcanic eruptions in Iceland have occurred along a continuous belt. The Eastern Volcanic Zone has the width of 1.5` from east to west.

The reason, as anticipated here, is that the small scale mantle convection roll found at 120 km depth rotates excerts force from west to east on the tectonic plate. At the same time the area is pulled by the North American Tectonic Plate eastwards. These opposite forces create the rift zones and volcanic systems.

Volcanic eruptions will start in the other volcanic zones one day, and intrusions have recently been noticed on Reykjanes Peninsula and within Öraefajökull Volcano. One small eruption occurred in the ocean out of Reykjanes in 1926, as can be seen on the list of this webpage: https://en.vedur.is/earthquakes-and-volcanism/articles/nr/1874.

The trenches of oceanic crust interact with the convecting mantle. At Sumatra the pattern looks like this (viewed from south):

The oceanic crust starts bending over the division line between rolls A and B. The crust bends. The outer arc forms over B. The oceanic crust material is then further subducted and enters the down-welling part of convection roll C, and enters the up-welling part between C and D, ending down below the volcano.

Between C and D, geoscientists have already found out that up-welling convection must be taking place underneath the back-arc basin.

This is not a scientific report, as the section is not to scale and no relevant measurements have been made. It is the methodology of comparing convection currents with surface features that is important.

This is based on Wikipedia https://en.wikipedia.org/wiki/Sumatra_Trench

The large scale convection does fix the point between F and G very accurately. The convection rolls have to be of equal height and width (Rayleigh-Bénard convection). The arrangement of the rolls is therefore not disturbed by the interaction between oceanic crust and rolls C and D.