The Phase X earthquake, which Fiema et al. (2001) label as the first earthquake, post-dates the fire of Phase VIII, which is securely dated and provides a terminus post quem in the late 6th century CE. This dating derives from the Petra papyri , which were burned in the Phase VIII fire. A provisional terminus ante quem is provided by the succeeding Phase XI, generally placed in the late 7th to early 8th century, although the dating of that phase remains uncertain. Fiema et al. (2001:115) caution that “no easily datable material can be associated with [Phase XI] deposits,” noting that “several 7th century sherds were found in strata which may have been created” during that phase. They conclude that Phase XI “could be dated to the 7th century A.D., probably its second half, and apparently after the first earthquake,” while also observing that other ceramic evidence suggests it “could have lasted longer, i.e. until the next earthquake.” Overall, Fiema et al. (2001:111) concluded that the date of the Phase X Earthquake was "not easy to determine." In contrast, Bikai and Perry (2012:95–97) favored a mid-8th century CE date for the Phase X earthquake, arguing that occupation of Petra’s North Ridge, which includes the Blue Chapel and Petra Church, continued into the 8th century CE and ended with the " large earthquake in 748/749 CE”, which they interpreted as responsible for the collapse of columns and walls in both the Blue Chapel and the Petra Church. Perry in Bikai et al. (2020:69) reported a single radiocarbon date from an animal bone recovered beneath a fallen column drum in the Blue Chapel, interpreted as refuse from an animal consumed by the inhabitants shortly before the Blue Chapel Phase V-3 collapse event, which was itself interpreted as earthquake destruction. This sample yielded a calibrated range of 658–782 CE (95.4%, 2σ), providing a broad but relevant terminus post quem for the destruction horizon.

With respect to causation, Fiema et al. (2001:111) state unequivocally that “there is no evidence whatsoever to suggest that the earliest structural destruction of the church complex was caused by factors other than natural ones, and an earthquake is the most acceptable explanation.” Stone-tumble deposits were observed throughout the complex, and the earthquake “damaged the already weakened structure of the church proper,” causing collapse of most of the columns in the basilica, followed by failure of the arches above the capitals and upper walls, including failure of the clerestory, as well as the fall of remaining roof elements that had survived the Phase VIII fire.

Further damage included visible deformation of Walls A, C, and F with Wall F "precariously toward the south", collapse of porticoes in the atrium, loss of vaulted ceilings and superstructure in multiple rooms, and extensive arch failure. At the same time, the absence of ground cracking, limited wall displacement at foundation level, and the survival of at least two columns in the baptistery as well as the central and side apses suggest that the event was not catastrophic. On this basis, Fiema et al. characterize the Phase X earthquake as a moderate event, “probably comparable to grades VII–VIII on the Modified Mercalli Intensity Scale.” Fiema et al. (2001) also noted that a predominantly north–south collapse was associated with the Phase X earthquake.