Precursory phenomena observed in the total electron content measurements before great Hokkaido earthquake of September 25, 2003 (<Emphasis Type="Italic">M</Emphasis> = 8.3) |
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Authors: | I E Zakharenkova I I Shagimuratov A Krankowski A F Lagovsky |
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Institution: | (1) West Department of IZMIRAN, Kaliningrad, Russia;(2) Institute of Geodesy, University of Warmia and Mazury, Olsztyn, Poland;(3) Immanuel Kant State University of Russia, Kaliningrad, Russia |
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Abstract: | In this paper the analysis of the ionospheric total electron content (TEC) variations obtained with using GPS measurements
before the Hokkaido earthquake (M = 8.3) is presented. Anomalous behavior of TEC was detected within several days before the
main event. Anomaly appeared as the local TEC enhancement situated in the vicinity of the forthcoming earthquake epicenter.
These structures occurred during 5 days prior to the shock at the same interval of local time. At the process of the earthquake
approach the amplitude of modification was increased, and it has reached the 85–90% level relative to the non-disturbed conditions
18 hours before the earthquake. The area of strong positive disturbance has extended over 1500 km in latitudes and 4000 km
in longitudes. The analysis have shown that according to the series of characteristics (its locality, affinity with the epicenter,
dome-shaped zone of manifestation, characteristic time of existence) the detected ionospheric anomaly may be associated to
the precursors of seismic activity. |
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Keywords: | ionosphere total electron content earthquake seismo-ionospheric anomalies |
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