Earthquake sequence at Eyjafjarðaráll in North Iceland
An earthquake sequence occurred 14 - 21 September 2012 offshore North Iceland, at the southern Eyjafjarðaráll graben.
Four earthquakes above magnitude M4 were detected and well felt in Siglufjörður and Ólafsfjörður, partly also in Sauðárkókur, Dalvík, Húsavík and Akureyri; i.e.19 September at 07:57 and 08:28 and 20 September at 09:27 and 19:42.
Some more events above M3 have been detected during this sequence, and altogether over 400 smaller events.
Eyjafjarðaráll is a graben structure between the Húsavík-Flatey fault and Kolbeinsey ridge. The Húsavík-Flatey fault is part of the Tjörnes Fracture Zone, which compensates the offset between the Northern Volcanic Zone and Kolbeinsey ridge. The present activity occurred in the transition zone between the graben and the Húsavík fault, not directly on the Húsavík-Flatey fault.
Earthquakes are not uncommon in this area, comparable earthquake sequences have occurred in 1996 and 2004 around the same location as the present one. They lasted for several days and earthquakes above M4 were measured.
It is impossible to predict if and how long the present sequence will continue. Although the activity calmed down, further events of around M4 and potentially above can not be excluded.