Subsidence events in the Krafla area, North Iceland, 1975-1979

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E. Tryggvason


In the inflation-deflation sequence of the Krafla magma chamber since its beginning in 1975, 12 deflation or subsidence events have been identified until May, 1979. The tilt and distance measurements relating to these subsidence events are discussed in some detail. All of these subsidence events are associated with horizontal magma flow along the N-S trending fissure zone, which goes through the central part of the Krafla caldera, to form a dike 3 to 5 m wide, 80 km long, and 1.0 to 2.5 km high from the bottom to the top. The total volume of magma, which flowed out of the Krafla magma chamber during these 12 events, is estimated as 481 x 106 m3, whereof 407 x 106 m3 are estimated to have flowed northwards, 72 x 106 m3 southwards and about 2 x 106 m3 came to the surface as basaltic lava.

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Tryggvason, E. (1980). Subsidence events in the Krafla area, North Iceland, 1975-1979. Journal of Geophysics, 47(1), 141-153. Retrieved from


Bjornsson, A. (1976) Jardhneringar vid Kroflu (Rifting and volcanism in the Krafla area 1975-1977) (in Icelandic). Natturufnedingurinn 46:177-240

Bjornsson, A., Saemundsson, K., Einarsson, P., Tryggvason, E., Gronvold, K. (1977) Current rifting episode in north Iceland. Nature 266:318-323

Bjornsson, A., Johnsen, G., Sigurdsson, S., Thorbergsson, G., Tryggvason, E. (1979) Rifting of the plate boundary in north Iceland 1975-1978. J. Geophys. Res. 84:3029-3038

Brandsdottir, B., Einarsson, P. (1979) Seismic activity associated with the September 1977 deflation of the Krafla central volcano in NE-Iceland. J. Volcanol. Geothermal Res. In press

Einarsson, P. (1978) S-wave shadows in the Krafla caldera in NE-Iceland, evidence for a magma chamber in the curst. Bull. Volcanol. 41:1-9

Gerke, K. (1977) Uber neuere horizontale und vertikale Krustenbewegung in Island. Mitteilungen der Technischen Universitiit Carolo-Wilhelmina zu Braunschweig XII, 4 pp.

Gerke, K., Moller D., Ritter, B. (1978) Geodiitische Lagemessungen zur Bestimmung horizontaler Krustenbewegungen in NordostIsland. In: Festschrifi fur Walter Hopcke, pp. 23-33. Hannover
Technische Universitat

Mogi, K. (1958) Relations between the eruptions of various volcanoes and the deformation of the ground surfaces around them. Bull. Earthq. Res. Inst. 36:99-134

Sigurdsson, O. (1976) Natturuhamfarir i Thingeyjarthingi (Natural catastrophes in Northeast Iceland) (in Icelandic). Tyli 6:3-20

Sigurdsson, O. (1977) Natturuhamfarir i Thingeyjarthingi (II) 1976-1978 (Natural catastrophes in Northeast Iceland (II) 1976-1978) (in Iceland). Tyli 7:41-56

Sindrason, S., Olafsson, H. (1978) A magnetoresistor geotiltmeter for monitoring ground movent. Nordic Volcanological Institute 78(06):1-7

Tryggvason, E. (1976) Landslagsbreytingar samfara jardskjalftunum 1975-1976 (Ground movement in North Iceland during the earthquake swarm of 1975-1976) (in Icelandic). Natturufrredingurinn 46:124-128

Tryggvason, E. (1978a) Tilt observations in the Krafla-Myvatn area 1976-1977. Nordic Volcanological Institute 78(02):1-45

Tryggvason, E. (1978b) Distance measurements in 1977 in the Krafla-Myvatn area and observed ground movements. Nordic Volcanological Institute 78(10):1-47

Ward, P.L., Bjornsson, S. (1971) Microearthquake swarms and the geothermal areas of Iceland. J. Geophys. Res. 76:3953-3983

Ward, P.L., Palmason, G., Drake, C. (1969) Microearthquake survey and the Mid-Atlantic Ridge in Iceland. J. Geophys. Res. 74:665-684