Analysis of evolution of NOAA 7912 active region on 19 October 1995

An analysis of a minor (B3.2) flare related to an X-ray jet in the reversed polarity NOAA 7912 active region is presented, focusing on various kinds o f activity observed in the H alpha line with the MSDP instrument. Using com plementary Yohkoh soft X-ray observations and a Kitt Peak magnetic field ma p we study the influence of a rather low and graduate energy release on fil aments, fibrils and chromospheric brightenings and their relevant coronal f eatures. We find that this small flare affected the entire AR and was assoc iated with strong up- and downflows along remote fibrils and filaments, whi ch appear to be connected by large-scale loops. It is shown that at least o ne of the observed brightenings was caused by downflow of the matter, thus, by the kinematic heating of the material. The filament in the vicinity of the hare footpoints changed the most: it broke into two parts, temporarily rose to higher altitudes inside the AR and even erupted outside of the AR, re-forming only three hours later. We show that even a minor flare can lead to important morphological and dynamical changes in an active region.