The extinct volcanic zone of Skagafjörður tells a story about the double nature of volcanism in Iceland in general. The eastern North Volcanic Zone has taken entirely over the volcanic and rifting functions.
The coherence between the South Iceland Seismic Zone and Tjörnes Fracture Zone becomes more appearent when comparint its location with the Skagafjörður volcanic Belt. The Tjörnes Fault Zone can be regarded as an EW-trending.
The large scale axis from Snæfellsjökull to Snæfell provides a connection to practically all the volcanic zones (and those classified as volcanic belts).