The SSC event of April 17 2002:a preliminary analysis from SEGMA array.

. We conducted a multi-station analysis of the April 17, 2002 SSC by means of high resolution measurements (1 second) conducted at three stations of SEGMA, the new South European Geomagnetic Array (Nagycenk, NCK, Mlat. 42.68^o, Ranchio, RNC, Mlat. 38.19^o, L'Aquila, AQU, Mlat. 36.22^o, along the same geomagnetic meridian ∼90^o). The characteristics of both the main impulse (MI) and the preliminary impulse (PI) are analyzed as a function of magnetic latitude. The PI is characterized by a positive variation along H and a negative variation along D. It is accompanied by a clear Pc3 wave activity at discrete frequencies ( ^∼40 mHz and ^∼60 mHz). We adopted also a different approach in which the geomagnetic signal is decomposed along axes associated with maximum (V_max) and minimum variance (V_min) orientation. The MI field, along V_max, is oriented at ~ 45^o from the H component; conversely, the PI field has a dominant component along V_min.