Surface deformation of the Krafla Fissure Swarm in two rifting events
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Vols. 1-18 (1924-1944), ISSN 0044-2801
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Abstract
The Krafla rifting episode in North Iceland has had 11 main tectonic events during the period December 1975 to May 1979. Each event has lasted from a few hours to several weeks. The first and eighth events affected to some extent the same part of the Krafla fissure swarm. These two tectonic events in the fissure swarm were characterized by down-faulting of a central area of the fissure swarm about 5-km-wide E-W and 20-km-long N-S. The resulting graben was boarded on both sides by an intensely faulted and fractured zone. These fracture zones showed spreading of 1.5 m in the first event and 2.66 m in the eighth one along the same reach. Elastic contraction on both sides of the fissure swarm added up to 1.4 m in the eighth event. The graben floor is estimated to have subsided about 1 m in the first event while a further subsidence of 1.1 m was observed in the 8th event. The flanks of the graben rose about 0.5 m during the latter event. The rise diminished away from the fissure swarm.
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References
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