Ra'ash shvi'it (רעש שביעית)

Ra'ash shvi'it is a poem - a type of poem known as a Piyyut (פיוט). Piyyutim (i.e. Piyyuts) are a type of Jewish liturgical poetry. This difficult to date (year wise) poem refers to a fast on 23 Shvat in memory of the victims of an earthquake which struck Tiberias and elsewhere. Ra'ash shvi'it literally translates as 'Seventh Noise' or 'Seventh Earthquake' but it can also translated as 'The Sabbatical Year Quake'.