Margalioth (1960) hypothesized that the Hebrew word translated as in wrath in the 23 Shvat fasting prayer found in the Cairo Geniza prayer book might conceal a numerical code revealing the year of the earthquake. Using one of the common Gematria ciphers, Margalioth calculated the value of in wrath as 679. Because the name Raʾash Sheviʿit indicates that the earthquake occurred in a Sabbatical Year and 679 is evenly divisible by seven, this number would qualify as a Sabbatical (seventh) year.

The next challenge was to determine the base year used for the Hebrew calendar in the mid-eighth century CE. Following the destruction of the Second Temple in 70 CE, the Hebrew calendar counted years from that date. If one adds 70 to 679, the result is 749 CE — precisely the year when 23 Shvat and 18 January coincide.

However, a complication arises: by the early tenth century CE, the reckoning of the Hebrew calendar was reformed into the system still used today (Stern, 2012: 334–335). In this modern system, 70 CE is no longer the starting point, and 749 CE is not a Sabbatical Year. How the calendar was calculated in the mid-eighth century before this reform remains uncertain.

Nevertheless, the excerpt cited by Karcz (2004) appears to assume a 70 CE starting date — since the destruction of Jerusalem to the date it happened in the Land of Israel, the count of ‘in wrath’. Thus, the main uncertainty lies not in the chronology itself, but in whether the Gematria coding was genuinely embedded in the prayer and which cipher was intended.