Scenic Areas of ‘Diamond Circle’ in North Iceland

Scenic areas appear in context with forces of nature. The Diamond Circle contains Goðafoss Waterfall, Mývatn Lake, Dettifoss Waterfall, Ásbyrgi Canyon, Húsavík Hot Springs and eventually the town of Akureyri.

Scenic Areas of Diamond Circle

Here some explanations are made:

1. Vaðlaheiði Tunnel goes right through a division line between mantle rolls. 2. Goðafoss is at the EW axis of the relevant polygon. 3, Mývatn area with Krafla and Námaskarð are located ath the edge of a mini-polygon. 4. Dettifoss is at border line of two polygons, providing conditions for a division between highland and lowland areas. 5. Húsavík is on the main division line of lower mantle. At Öxarfjörður a major geothermal area is found, still not included in the circle. The polygons provide clear topographical NS features, including Ásbyrgi.

The analysis thereby provides some explanation for all the sites. Description is found at the website https://www.northiceland.is/diamondcircle

Dettifoss Alignment Calculated According to Mantle Current Flow

The tectonics of the area of Dettifoss follow the upper most convection rolls of 120 km below the surface. The formula shows exactly the direction of the tectonic feature creating the edge of Dettifoss Waterfall.


Central Point of Iceland Shelf Revisited

Drawing a continuation of the two ridges, Reykjanes Ridge and Kolbeinsey Ridge, they meet in one point. This point is also central to the elliptical form noticable of the Icelandic Shelf. This form has developed gradually, as different rift axis have been replacing each other through millions of years.

Central Point of Iceland

The yellow lines are the theoretical continuations of the two ridges found north and south of Iceland, until they meet at one point.

The NS axis goes right through Hekla and Eyjafjallajökull in South Iceland. In turn, Eyjafjallajökull forms a similar ‘small’ ellypse, around the same axis, as shown here:

Central Axis of Iceland Shelf and Eyjafjallajökull

The central point forms the crater of Eyjafjallajökull. The EW axis of the polygon connects Eyjafjallajökull and the Katla System.


Was there One More Rift Axis of Iceland?

Considering the jumps of rift zones over Iceland, and seeing the pace of those ‘jumps’, there seems to be a possibility that another rift zone opened before the ‘first one’.

Was there another Rift Axis?

The activity would then have occurred about 25 million years ago, probably at the same time as when the Northwest Rift Axis was active. The prospective rift axis is pointed out with a question mark.


The Interval Between Volcanic Zones in Iceland

The interval between volcanic zones in Iceland is regular, as shown here:

Map from Árni Hjartarson – The Skagafjörður Volcanic Zone – an ephemeral Rift Zone

As the arrows show, the NE-SW alignment is achieved along the same pattern, namely that of the Reykjanes Ridge. The red lines marking up-welling of convection rolls, fit for all four sets of volcanic zones.

The sequance can be made more clear, by widening the division lines between the upper most convection rolls, found at 120 km depth.

The Jumps of Rift Axis over Iceland

It should also be mentioned, that Öræfajökull is on the fourth line, in accordance with the interval between the up-welling NE-SE aligned division lines between convection rolls.

The so-called ‘jumps’ therefore always occur regularly in the SW of Iceland where the axis is aligned NE-SW. One jump occurs over exactly 3° from east to west along the relevant latitude. The distance between the North Volcanic Zone, and the recently extinct Skagafjörður Volcanic Zone is also 3° at the latitudes of the Tjörnes Fracture Zone. The reason is that each convection roll spans 1.5° from east to west, and a pair of convection rolls, representing one unit in the convection rolls system, spans 3° from east to west.

This can be compared with the results of ISNET measurements by the National Land Survey https://www.lmi.is/

Drift Vectors and Rift Axis ‘Jumps’

The northern component of tectonic drift, in addition to the easterly and westerly components of the vectors is a rather new finding, after GPS was used to measure tectonic drift on global scale. The east and west components had been measured previously. Describing tectonic drift of Iceland, one should say that the western half drifts about 2.5 centimeters a year to the NW, and the eastern half drifts about 2 cm a year to the NE. As a consequence, the country widens up from the middle rift areas by about 2 cm a year, 1 cm to the east and 1 cm to the west.


Shift of Fissure Alignment Along Central Iceland

Volcanic Fissures in South Iceland are generally oriented NE-SW, but in North Iceland they are aligned more NS. The reason is that in South Iceland large polygons lead to pulling effect NW and SE, whereas the more complicated pattern in North Iceland leads to pulling to the East and West.

Shift Zone from NE-SW alingment to NS alingment

Most of SVB (Snæfellsnes Volcanic Belt) is aligned along the zone, covering two convection rolls. The WVZ (West Volcanic Zone) turns in the same way as the MIB (Mid Iceland Belt) within the zone, and the EVZ (East Volcanic Zone) and NVZ (North Volcanic Zone) meet within the zone, showing abrupt shift from NE-SW alignment to NS oriented fissures. The Öræfajökull Volcanic Belt covers two convection rolls, ending with Snæfell Volcano, at the southern border line of the shift zone.

It is also curios that the lower yellow line, is found along Hveravellir, equadistant from Snæfellsjökull and Snæfell, also found on that latitude. Those two volcanoes both mark the end points of the peripheral volcanic zones of SVB and ÖVB. Difectly north of Hveravellir is the extinct SKVB (Skagafjörður Volcanic Belt), and directly south of Hveravellir are Hekla and Eyjafjallajökull, all found on a NS-axis. Therefore, the Shift Zone Line also plays a decisive role in the overall symmetry of the distribution of the volcanic zones.