Fiema et al. (2001:115–117) emphasize that the post–Phase X history of the Petra Church complex is poorly understood and difficult to date, owing to fragmentary and enigmatic stratigraphic sequences in the upper layers. They stress that this phase was long-lasting and required further subdivision, but that attempts to connect areas of possible human interference into meaningful spatially and temporally defined units would be “pure guesswork.” Consequently, the available evidence is presented as a record of activities extending from the Phase XIIA Earthquake until modern times, encompassing the late Umayyad– Abbasid, Mamluk, and early Ottoman periods, without secure chronological attribution for most architectural features.

Despite these difficulties, Fiema et al. (2001) note indications of further earth tremor(s) in the form of upper stone-tumble deposits. These tumbles are more difficult to interpret than earlier destruction layers, as they may represent a single seismic event or multiple events occurring within a relatively short time span, and one must also account for ongoing natural deterioration and decay of the ruins. Separation of major stone collapses into discrete loci proved possible only in a few areas, and in the nave no evidence of collapse beyond that associated with Phase X could be detected.

The most compelling evidence for a later earthquake derives from Room X, where two or three of the four columns supporting the canopy over the baptismal font broke and collapsed onto the surface of locus E3.30A. Fiema et al. argue that this fall was “hardly due to natural deterioration.” The southeastern column broke at a level corresponding to the top of the already-filled interior, approximately 1.2 m above the floor, and nine drums fell in a well-aligned east–west row. Four drums of the southwestern column formed a parallel row, preserving an almost exact east–west orientation that contrasts sharply with the predominantly north–south collapse observed during the Phase X earthquake. That said, Fiema et al. (2001) noted that "a few drums of the third (probably NE) column and a capital fell on the same surface but not in the same orientation as the others".

Additional collapse in Room X included large quantities of ashlars and other stone material attributed to the destruction of adjacent walls. The presence of canopy voussoirs outside Wall TT indicates that parts of the canopy structure also failed, possibly falling across an already damaged wall. Fiema et al. interpret this combination of aligned column fall, architectural breakage, and associated wall collapse as strong evidence for a seismic event distinct from earlier phases.

In the aisles and apses, this event is expressed by extensive stone-tumble deposits occurring at higher elevations than the earlier earthquake destruction. In the north apse, an approximately 0.5 m-thick tumble filled the eastern aisle and the apse interior, containing glass, stone tesserae, marble fragments, and several fallen column drums. These deposits are clearly separated stratigraphically from earlier destruction layers.

The apses appear to have survived the Phase X earthquake relatively intact but fared much worse during the Phase XIIA seismic event, which suggests higher levels on local intensity were experienced during the Phase XIIA event. Fiema et al. describe complete collapse of the semidome, with massive tumbles covering the bema and overlapping its eastern edge. The tremor “buckled and broke the structure of the semidome,” causing it and some wall mosaics to fall onto the central and eastern bema, while stone deposits concentrated westward in a pattern similar to that observed in the baptistery. Comparable stone-tumble deposits ere also found in the northern rooms and the atrium. It should be noted that Fiema et al. (2001) label the Phase XIIA earthquake(s) as the second earthquake.