Geophysical events

Authors

  • Anonymous


Abstract

Krafla Caldera, Mývatn Area, Iceland (65.71°N, 16.75°W). The following is a report from Karl Gronvold and Páll Einarsson.

The gradual inflation after the minor December event (see SEAN Bulletin, 4 (12)) was reversed about 1 February when very slow deflation began and the earthquake activity associated with inflation stopped. As measured at the Krafla power house, the initial deflation rate of about 0.5 microradians/day increased on 7 February to about 1.3 microradians/day. In the evening of 10 February, a dense microearthquake swarm began near the S rim of the Krafla caldera and started to propagate southward. At about the same time the deflation rate increased at Krafla, reaching a maximum of 7 microradians/day on 12 February. The rate of deflation decreased gradually thereafter; on 17 February it stopped, and on 21 February inflation started again. The deflation of 40 microradians is somewhat larger than the December deflation but still only about ⅙ of the last major deflation-rifting event in May 1979 (see SEAN Bulletin, 4 (5)).

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