Energy release stages of the complex solar flare of October 25, 1994

The morphology and evolution of the 1n/C4.7 flare which occured in the active region NOAA 7792 on October 25, 1994 are studied using the observations in the SXR, optical and radio range. The preflare coronal magnetic field structure is inferred comparing the force-free magnetic field extrapolations of the photospheric longitudinal magnetograms with structures seen in YOHKOH SXT images and H-alpha filtergrams. The preflare arcade consisted of a highly sheared system of loops which was abruptly transformed during the impulsive energy release. The further evolution was basically following the two-ribbon flare scenario, including a protrusion of the energy release process into the strong magnetic field of the major sunspot, as well as an interaction with an emerging flux region.