Clark (1987:489–490) documents a major earthquake destruction horizon affecting H.1, H.3, and H.6 at the end of the Umayyad period, arguing that the Post Stratum II gap “may have been initiated by the partial structural collapse of the building,” possibly beginning in the “747 A.D. earthquake [JW: i.e. one of the earthquakes in the mid-8th century CE seismic sequence],” with continuing collapse thereafter. In these areas, the stratigraphy shows that the major collapse lay directly above Umayyad occupation surfaces, with barracks walls along the southwest side falling northeastward into the courtyard and upper floors collapsing into lower rooms, indicating catastrophic structural failure rather than gradual decay.

At H.3, Clark (1987:489) records collapse in loci H.3:013 and H.3:010, which he interprets as “collapse into the ground floor room from the upper floor,” including flat roofing beams, limestone flooring slabs, masonry blocks, chinking stones, plaster, and mortar. The collapse debris contained predominantly Umayyad pottery, demonstrating that the upper storey was still in use when the structure failed, and securely dating the destruction to the Late Umayyad phase rather than to earlier Roman or Byzantine occupation.

In H.1, Clark (1987:488) identified a 0.26 m thick ashy deposit overlying Surface H.1:007 that contained Umayyad sherds, glass fragments, barley seeds, and a mixed assemblage of animal and human bones. He notes that the presence of human remains is difficult to explain except as “partial remains of a person (or persons) killed in the earthquake that seems to have put an end to the Umayyad occupation,” directly linking human casualties with seismic destruction and final abandonment of this sector.

H.2 preserves a complex archaeoseismic sequence above Late Roman and Early Byzantine occupation, where Clark (1987:490) describes a buildup of windblown loess (H.2:009), overlain by rock tumble (H.2:007) and further windblown deposits (H.2:006), followed by an ash-filled fire pit (H.2:005) and finally a “massive tumble of fallen masonry including stone ceiling beams” (H.2:004). Although the terminus post quem is after ~400 CE, Clark concludes that “on the balance of probability” the final collapse occurred “at about the end of the Umayyad period,” linking this destruction to the same regional earthquake that devastated H.1, H.3, and H.6.

Additional evidence for earthquake damage comes from the corner towers , where Clark (1987:490) reports that the floors and ceilings collapsed, noting that this destruction can only be assigned a terminus post quem but is most plausibly associated with the same Late Umayyad seismic catastrophe that caused the widespread structural failure, human casualties, and abandonment observed across the fort.