Geologic Background:
Kolbeinsey Ridge is divided from Iceland by an
oblique running transform fault, the Tjornes Fracture
Zone (TFZ). It is a slow-spreading ridge with an
estimated asymmetric spreading of 10mm/year. The ridge
crest is nearly bare of sediments, although the
bathymetry is very shallow. Kolbeinsey Ridge is cut by
two major transform faults, the Spar Fracture Zone and
the 70.8 Fracture Zone, and is thus divided into three
segments, the Southern Kolbeinsey Ridge (SKR0, the
Northern Kolbeinsey Ridge (NKR), and the Central
Kolbeinsey Ridge (CKR). The most active part of the ridge
is the CKR north of the Spar Fracture Zone.
Historic Activity:
- A submarine eruption was reported in 1372 on the
Kolbeinsey Ridge NW of Grimsey Island at about 66.67 N,
but the location is uncertain.
- Other reports of submarine eruptions N of Iceland
have an even more uncertain location (1755) or have be
discredited (1783 and 1838).
Recent Activity:
- A submarine eruption or dike intrusion on Aug. 30,
1999 was identified by seismic events at the Vedurstofa
Islands along the Kolbeinsey Ridge south of the Spar
Fracture Zone. 143 earthquakes.
Data Sources:
- Global Volcanism Network (V. 24, No. 10).
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