TEC variations over the near-epicentral region before the Haiti earthquake of Jan. 12, 2010

We present the investigation of the anomalous TEC increase relative to the quiet conditions for the near-epicentral region as possible earthquake precursors for the case of Haiti strong seismic event (Jan. 12, 2010, 21:53UT; 18.46N, 72.5W; M7.0). We defined seismically-induced anomaly as strong deviation from the quiet background level derived from differential TEC maps built on the basis of NASA IONEX product. We defined background level as running median for 7 days before the current calculation's moment. The anomalies of the TEC disturbances were observed 3 days before the Haiti earthquake of Jan. 12, 2010 and looked like the strong TEC increase for more than ~40% in magnitude. They were elongated ~15 deg. in latitudinal direction and ~25 deg. in longitude at the near-epicentral region and existed from Jan. 10, 22UT till Jan. 12, 08UT, 2010. Similar effects took place at the magnetically conjugated area too. The magnetic conjugation of the observed phenomena strongly evidences in favor of the hypothesis of the F2-region ionospheric plasma vertical drift under influence of the zonal electric field of seismic origin as the principal reason of the phenomena. Geomagnetic situation for the considered period was relatively quiet. Thus, the anomalies are not due to the solar or geomagnetic activity. All the mentioned above allow us to treat such anomalous deviations as ionospheric seismo-precursors.