The poem
Raʾash Sheviʿit (רעש שביעית)
refers to a fast observed on the 23rd of the Hebrew month of Shvat in memory of
the victims of an earthquake that caused destruction in
Tiberias and elsewhere. When the correspondence of 23 Shvat
is compared with Julian calendar dates between 745 and
752 CE, it is found that 23 Shvat aligns with the 18 January
date given by Theophanes and Cedrenus for the Holy Desert
Quake — and only in 749 CE.
Although 23 Shvat and 18 January also fall close together in
746 CE, archaeoseismic coin evidence from
Bet Sheʿan rules out this
year, as 746 CE predates the
A.H. 131
(31 August 748 – 19 August 749 CE)
terminus post quem
established by the coins. This convergence between two
independent traditions thus points to 749 CE and a date
around 18 January for the earthquake.