Hirschfeld et al. (1997:6) note that, while "it is not clear what fate befell the baths [in Phase II] at the end of the Byzantine period," it "seems that the place was struck by one of the earthquakes that occurred in the region." The resulting damage, they state, is "attested in the 'Muʿāwiya inscription' (no. 54) discovered at the site." This inscription, "dated accurately to the year 662 C.E.," details renovation activity carried out by Muʿāwiya, the first Umayyad Caliph, but does not specifically mention an earthquake or prior damage to the site.

Magness (2010:153–161) re-dated Phase II at Hammat Gader to the Umayyad rather than the Byzantine period. Her reassessment was based on coins and pottery, and she argued that Hirschfeld et al. (1997) relied too heavily on inscriptions to establish the chronology, leading to conclusions that conflicted with the material evidence. In Magness’s re-dating, the Phase IIA destruction — if indeed seismic — would most plausibly correspond either to the Jordan Valley Quake(s) of 659/660 CE or to one of the events within the 749 CE Sabbatical Year sequence.

If the Jordan Valley Quake(s) of 659/660 CE was the causative event, then the Muʿāwiya inscription (no. 54), which records renovation activity commissioned by Muʿāwiya and dates to 662 CE, would likely represent a response to that earthquake. In this case, Hirschfeld et al. (1997)’s Phase IIB earthquake would be synonymous with his Phase IIA event and more accurately referred to as the Phase II earthquake.