Myvatn - Krafla
Geology of the Krafla Area
The Krafla high-temperature geothermal area is situated within a neovolcanic zone and takes its name from the hyaloclastic Mt. Krafla. Running across the volcanic zone is an active fissure swarm, where the American and Eurasian continental plates are drifting apart and new land is in the process of formation. Studies of tepra layers suggest that volcanic episodes lasting 10-20 years each occur at Krafla at intervals of 250-1000 years. The most recent episode began late in 1975 and has probably ended with the last eruption there in September 1984.
Iceland - Island Iceland - Island Iceland - Gufudalur
Iceland - Island Iceland - Island Iceland - Island

At a depth of 3-8 km beneath the caldera where the Krafla fields lies is a magma reservoir which is responsible for local volcanic activity. Magma - molten rock -builds up in the reservoir until it is released as rock intrusions or in the form of volcanic eruptions causing the land surface to sink. There have been 21 cycles of land rising and sinking during the present Krafla episode, nine of which have resulted in volcanic eruptions.
Extensions of geothermal fields can be identified by their high electric conductivity (low resistivity). There is a large resistivity low in the central part of the Krafla caldera extending to a depth of 700-800 m, and two smaller ones at the caldera rim. Beneath them, different rock types increase the resistivity. Hyaloclastities dominate down to a depth of 800 m, below which basalt strata with intrusions become much more frequent.
  Iceland - Island  
Krafla Power Station
Exploratory drilling for harnessing geothermal steam began in the Krafla area near Lake Mývatn in North Iceland in 1974, and drilling of production wells, construction of the power station and erection of the 132 kV transmission line to Akureyri commenced in the summer of 1975. Design of the power house and other buildings was based on two 30 MW turbine units.
The first turbine, which went on line in August 1977, was initially operated at reduced capacity, but has been in recent years operated at full capacity, except for few months during summer.
The station was designed and built for the Icelandic State and its operation was originally managed by a State appointed committee, until it was taken over by the State Electric Power Works on January 1. 1977. The National Power Company purchased the Krafla power station from the State and took over its ownership and operation at the beginning of 1986.
There are three production fields; Leirbotnar, southern slopes of Mt. Krafla, and Hvíthólar, each with its individual production characteristics. The largest part of the geothermal reservoir is at boiling point and the maximum recorded temperature is 350°C at a depth of 2000 m. The depth of the productions wells differ from about 1000 m. for low pressure wells to about 2000 m for high pressure wells. The deepest well, KG-12 is 2222 m.
Initially, various difficulties were encountered in exploration and drilling for steam, largely due to volcanic activity. Until about 1978, magmatic gasses flowed into the geothermal reservoir, destroying wells due to corrosion of their casings. These magmatic effects are now on the wane.