Geophysical Journal | 2007 volume 29 2

Geomagnetic disturbances and the strongest earthquakes in the area of the Sumatra island

© F.I. Sedova, T.A. Mozgovaya, V.G. Bakhmutov

In connection with catastrophic earthquakes in Sumatra region 26.12.2004 and 28.03.2005 geomagnetic situation was studied for the period from October 2004 to April 2005. Geomagnetic observations have been analyses at the midlatitudinal Kiev observatory with the data from other observatories. An analysis has been conducted following the hypotheses of relation between catastrophic earthquakes and abrupt changes in H-component of geomagnetic field which was demonstrated earlier on the examples of the Vrancea seismic zone. A set of anomalous geomagnetic phenomena as magnetic storms and sub-storms has been revealed. The results do not contradict the assumption of a triggering mechanism of the magnetic storm effect on the seismicity. It has been suggest that if in the December earthquake the main role could be played by prior "main gradient" caused by magnetic storm, then in March earthquake was probably caused by a succession of prior magnetic sub-storms.

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