Local changes in the total electron content immediately before the 2009 Abruzzo earthquake

Ionospheric TEC (total electron content) variations derived from GPS measurements recorded at 7 GPS stations in Northern, Central and Southern Italy before and after the 2009 Abruzzo earthquake (EQ) of magnitude Mw6.3 were processed and analyzed. The analysis included interpolated and non-interpolated TEC data. Variations in the TEC of both regional and local characteristics were revealed.
Several regional changes were observed in the studied period: 1 January–21 April 2009. After analyzing non-interpolated TEC data
of 5 GPS stations in Central Italy (Unpg (Perugia), Untr (Terni), Aqui (Aquila), M0se (Rome) and Paca (Palma Campania, (Naples)),
a local disturbance of TEC was also found. This local TEC disturbance arises preparatory to the EQ main shock occurred at 01:32 UT on 06 April 2009, maximizes its amplitude of ~0.8 TECu after the shock moment and disappears after it. The local TEC disturbance was confined at heights below 160 km, i.e. in the lower ionosphere.