Report on Krafla (Iceland) — December 1975
Natural Science Event Bulletin, vol. 1, no. 3 (December 1975)
Managing Editor: David Squires.
Krafla (Iceland) Minor steam eruption and lava flow
Please cite this report as:
Global Volcanism Program, 1975. Report on Krafla (Iceland). In: Squires, D. (ed.), Natural Science Event Bulletin, 1:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.NSEB197512-373080.
65.715°N, 16.728°W; summit elev. 800 m
All times are local (unless otherwise noted)
A minor eruption consisting mainly of steam began at about 1120 on 20 December. A small lava flow also occurred. The eruption was preceded by minor local earthquakes that began at about 1000. A 2-km-long fissure opened, and lava was erupted from three vents. The main lava flow lasted for 1 hour, and the eruption was essentially over by 1700 that same day.
Geologic Background. The Krafla central volcano, located NE of Myvatn lake, is a topographically indistinct 10-km-wide caldera that is cut by a N-S-trending fissure system. Eruption of a rhyolitic welded tuff about 100,000 years ago was associated with formation of the caldera. Krafla has been the source of many rifting and eruptive events during the Holocene, including two in historical time, during 1724-29 and 1975-84. The prominent Hverfjall and Ludent tuff rings east of Myvatn were erupted along the 100-km-long fissure system, which extends as far as the north coast of Iceland. Iceland's renowned Myvatn lake formed during the eruption of the older Laxarhraun lava flow from the Ketildyngja shield volcano of the Fremrinamur volcanic system about 3800 years before present (BP); its present shape is constrained by the roughly 2000 years BP younger Laxarhraun lava flow from the Krafla volcanic system. The abundant pseudocraters that form a prominent part of the Myvatn landscape were created when the younger Laxarhraun lava flow entered the lake.
Information Contacts: H. Sigtryggsson, Icelandic Meteorological Office.