Gravity and height variations during the present rifting episode in Northern Iceland

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W. Torge
E. Kanngieser


In 1975, a rifting episode started in the neovolcanic zone of northern Iceland, consisting of a succession of slow inflation periods and rapid subsidence events, which is still going on. The center of activity is situated below the Krafla caldera, and the rifting process is affecting the 80-km-long fissure swarm associated with this central volcano. Gravity and height variations associated with this process have been investigated by re-observing profiles earlier established in the Namafjall and in the Gjastikki area, situated nearly 10 km south and north of Krafla respectively, as well as by the re-observation of a number of gravity stations in the northern part of the fissure zone, in 1976, 1977, and 1978. By repeated observations with 2 or 3 LaCoste-Romberg gravity meters, the accuracy obtained in each gravity survey is of the order of ± 10 x 10-8 ms-2. In the profiles crossing the fissure zones, a rate of gravity increase of more than 100 x 10-8 ms-2/a has been found in the central part, while gravity at the flanks decreases at the same order. These variations are correlated with subsidence and elevation rates of the order of 0.5 m/a.

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Torge, W., & Kanngieser, E. (1980). Gravity and height variations during the present rifting episode in Northern Iceland. Journal of Geophysics, 47(1), 125-131. Retrieved from
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Bjornsson, A. (1976) Rifting and volcanism in the Krafla area 1975-1977. Natturufraedingirinn 46:177-240 (In Icelandic, with English summary)

Bjornsson, A., Johnsen, G., Sigurdsson, S., Thorbergsson, G., Tryggvason, E. (1978) Rifting of the plate boundary in North Iceland 1975-1978. Nordic Volcanological Institute 7807:1-31

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

Palmason, G., Saemundsson, K. (1974) Iceland in relation to the Mid-Atlantic Ridge. Annu. Rev. Earth Planet. Sci. 2:25-50

Schleusener, A. (1943) Die Gravimetermessungen. In: Niemczyk, O. (Ed.) Spalten auf Island, pp. 124-175. Stuttgart. Wittwer

Schleusener, A. (1974) Gravity measurements in N-Iceland between Eyjafjord and Vopnafjord. Presented at NATO Adv. Study Inst. Geodynamics of Iceland and the North Atlantic Area, Reykjavik

Schleusener, A., Torge, W. (1971) Investigations of secular gravity variations in Iceland. J. Geophys. 37:679-701

Schleusener, A., Torge, W., Drewes, H. (1976) The gravity field of northeastern Iceland. J. Geophys. 42:27-45

Spickernagel, H. (1966) Hohenmessungen in Nord-Island. Mitt. aus dem Markscheidewesen 73:139-152

Spickernagel, H. (1980) Results of height measurements in Northern Iceland 1965/1977. J. Geophys. 47:120-124

Torge, W., Drewes, H. (1977a) Gravity variations with time in northern Iceland 1965-1975. J. Geophys. 43:771-790

Torge, W., Drewes, H. (1977b) Gravity changes in connection with the volcanic and earthquake activity in northern Iceland 1975/1976. Jokull 27:60-70

Torge, W., Wenzel, H.-G. (1976) Gravimetric Earth tide observations in Iceland. Bull. d'Inf. marees terr. no. 74:4312-4318, Bruxelles