Anomalous behaviors of geomagnetic diurnal variations prior to the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0)
Abstract
There have been many reports on ultra-low-frequency (ULF) electromagnetic phenomena associated with earthquakes in a very wide frequency range. In this study, unusual behaviors of geomagnetic diurnal variations prior to the 2011 off the Pacific coast of Tohoku earthquake (Mw9.0) have been reported. Ratios of diurnal variation range between the target station Esashi (ESA) which is about 135 km from the epicenter and the remote reference station Kakioka (KAK) about 302 km distant to the epicenter have been computed. The results of 10-day running mean of the ratios showed a clear anomaly exceeding the statistical threshold in the vertical component about 2 months before the mega event. This anomaly is unique over a three-year background, and the further statistical test indicates that this anomaly is unlikely a random anomaly, which is highly suggestive of correlation with the mega event. The original records of geomagnetic fields of the ESA station also exhibits continuous anomalous behaviors for about 10 days in the vertical component approximate two months prior to the Mw 9.0 earthquake.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMNH33B1649H
- Keywords:
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- 4317 NATURAL HAZARDS Precursors;
- 4339 NATURAL HAZARDS Disaster mitigation;
- 4307 NATURAL HAZARDS Methods