Report on Krafla (Iceland) — December 1980
Scientific Event Alert Network Bulletin, vol. 5, no. 12 (December 1980)
Managing Editor: David Squires.
Krafla (Iceland) Four days of slow deflation, then inflation resumes
Please cite this report as:
Global Volcanism Program, 1980. Report on Krafla (Iceland). In: Squires, D. (ed.), Scientific Event Alert Network Bulletin, 5:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198012-373080.
65.715°N, 16.728°W; summit elev. 800 m
All times are local (unless otherwise noted)
Ground level remained about the same until 25 December when four days of very slow deflation began. Total deflation was about 1/3 the amount recorded during the October eruption (5:10). At the end of the deflation episode, a swarm of small indistinct earthquakes was recorded, with epicenters about 10 km N of the caldera center. Inflation resumed on 29 December, and by 8 January the caldera had nearly returned to its pre-deflation ground level.
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: G. Sigvaldason, NVI.