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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy<br />

(S) - <strong>IASPEI</strong> - International Association of Seismology and Physics of the Earth's<br />

Interior<br />

JSS010 Poster presentation 2083<br />

Occurrence of precursory effects of Kythira 2006 earthquake in GPS TEC<br />

variations<br />

Mrs. Irina Zakharenkova<br />

Irk Shagimuratov, Andrzej Krankowski, Galina Yakimova<br />

Total electron content of the ionosphere (TEC) is one of the most effective parameter to investigate the<br />

ionospheric effects associated with natural and technogenic hazards. GPS technique gives opportunities<br />

to detect spatial and temporal changes of the ionosphere during geomagnetic and seismic events. In<br />

this report we present the specific features of TEC behavior as possible precursors of Southern Greece<br />

earthquake of January 8, 2006 (M6.8). The epicenter position was 36N, 23E. For this purpose we used<br />

both the TEC data of nearest to the epicenter Euref-IGS stations and TEC maps over Europe. The<br />

favorable circumstance for this analysis was the quiet geomagnetic situation during the period previous<br />

to the earthquake. One day prior to earthquake the characteristic anomaly was found out as the daytime<br />

significant increase of TEC level at the nearest stations up to the value of 50% relative to the<br />

background condition. To estimate the spatial dimensions of seismo-ionospheric anomaly the differential<br />

mapping method was used. The ionosphere modification as the cloud like increase of electron<br />

concentration situated in the immediate vicinity from the forthcoming earthquake epicenter was<br />

revealed. The amplitude of modification reached the value of 50% relative to the non-disturbed<br />

condition and was in existence from 10 UT till 22 UT. The area of significant TEC enhancement had the<br />

sizes of about 4000 km in longitude and 1500 km in latitude. The revealed anomaly we have associated<br />

with precursors of the seismic event amenably to its peculiarities (its locality, affinity with the epicenter,<br />

cloud like zone of manifestation, characteristic time of existence).<br />

Keywords: precursors, ionosphere

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