Report on Krafla (Iceland) — February 1978
Scientific Event Alert Network Bulletin, vol. 3, no. 2 (February 1978)
Managing Editor: David Squires.
Krafla (Iceland) Inflation continues, after intrusion of 80 x 106 m3 in January
Please cite this report as:
Global Volcanism Program, 1978. Report on Krafla (Iceland). In: Squires, D (ed.), Scientific Event Alert Network Bulletin, 3:2. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN197802-373080.
65.715°N, 16.728°W; summit elev. 800 m
All times are local (unless otherwise noted)
"Since 22 January, the center of Krafla caldera has been inflating at a similar rate as before. It is expected that the level at which previous deflation events were triggered could be reached near the end of June. The center of the January rifting is about 40 km N of the center of Krafla caldera. Large-scale rifting took place as in previous events, but weather conditions have prevented detailed measurements. The volume of magma estimated to have left the central reservoirs below Krafla caldera during this event is 80 x 106 m3. This remained below the surface, since no eruption took place. The site of the main rifting is just S of the area where the main rifting took place following the initial outbreak in December 1975, but is about 10 km N of other events since 1975. This is a marked change in behavior, as all other rifting events along the fault swarm have been centered closer to the caldera. According to newspaper reports, the geothermal power station recently built within Krafla caldera has now started electricity production at 7-8 megawatts."
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: K. Grönvold, NVI.