Modification of electron density profile about the earthquake epicenter by GPS data

For testing the hypothesis about the modification of an ionosphere F2-layer in the epicenter area several days before the earthquake which occurred on August 17, 1999 in Turkey, the data from the stations removed from seismic zone were processed. IGS station coordinates: ZECK - 43.79N, 41.57 W; ZWEN 55.7 N, 36.76 W. The ionosphere state analysis was carried out during on August 13-18. The electronic concentration profile and its maximal meaning in a F2-layer were considered. The variations of an electronic plasma maximum were received by radio translucence method on the GPS satellite, observable simultaneously with stations ANKR, ZECK and ZWEN. For definition of high-altitude structures of an ionosphere the standard RINEX-files of observations introduced on a site http://garner.ucsd.edu/pub were used.