Tjörnes Fracture Zone | John Seach



66.30 N, 17.10 W
Submarine volcano
depth unknown

Tjörnes Fracture Zone is a submarine volcano located 10 km off the north coast of Iceland. It is a transform fissure zone of the mid atlantic ridge.

Tjörnes fracture zone is an 80 km wide zone of high seismicity marked by two faults. Húsavík fault, is marked by land surface depressions occupied by lakes. Guðfinnugjá is a large normal fault.

2013 Earthquake swarm
An earthquake swarm has occurred in northern Iceland in April 2013. The swarm was located on the Tjörnes Fracture Zone between Grimsey and the mainland. In the 48 hours to 4th April 2013 (02:19 hr, local time) there were 813 earthquakes. 522 earthquakes were between magnitude 2-3, 86 greater than magnitude 3. The largest earthquake was magnitude 5.3. The transform fault has historically been the site of underwater eruptions. The most recent eruption was in 1868. This earthquake swarm may indicate an underwater eruption is occurring.

2012 Earthquakes
An earthquake swarm was detected in NE Icland along the Tjornes Fracture Zone on 1 November 2012. The swarm was located about 100 km east another earthquake swarm which began on 21 October 2012. The new swarm contained about 30 earthquakes with a maximum magnitude of 3.

Further reading
Sæmundsson, K., 1974. Evolution of the axial rifting zone in northern Iceland and the Tjornes fracture zone. Geological Society of America Bulletin85(4), pp.495-504.

Rögnvaldsson, S.T., Gudmundsson, A. and Slunga, R., 1998. Seismotectonic analysis of the Tjörnes Fracture Zone, an active transform fault in north Iceland. Journal of Geophysical Research: Solid Earth103(B12), pp.30117-30129.

Tjörnes Fracture Zone Volcano Eruptions