On Shabbat, when I took back the Sefer Torah to the safe (which houses three Sifrei Torah), one of the Sifrei Torah was removed, which I did not notice, the Sefer Torah in the middle slipped and fell on its side in the safe (safe is about a meter above the ground). Besides myself, at the time of taking the Torah, there was only one other person. What is the halachah in this regard? I informed the president of the Kehilah as such today.

The reason to fast if a Sefer Torah falls is because of the dishonor that came upon the Torah and the need to atone for that. In this event the dishonor is minor since it only slipped as appose to falling and only in the safe as appose to on the floor. In this case giving Tzedakah will be appropriate. (Tzitz Eliezer 5; 1, 9)