The Tjörnes Fracture Zone (TFZ) is a tectonically complicated area. It connects the North Iceland Volcanic Zone (NVZ) and the southern end of the Kolbeinsey Ridge. This 50 km wide fracture zone is characterised by seismic activity, crustal extension and transform faulting. The volcanic fissure swarms of the Northern Volcanic Zone are connected to the southern end of Tjörnes Fracture Zone. For example, its southeast end is connected to the Krafla fissure swarm.