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.
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.
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