Groot et al. (2006:183) reported discovery of a nearly complete Umayyad lamp in Square 4 of Area B (Barracks – B.6.038), located in the Post-Stratum gap above and later than the third-earthquake layer. Above the lamp was a 0.7 m-thick tumble deposit containing some roof beams and many wall blocks. They observed that the basalt roof beams found embedded in the lowest tumble level (B.6.032) suggest initial massive destruction rather than gradual decay over time. The upper tumble layer included wall blocks and yielded one Late Islamic (1174–1918 CE) and one Ayyubid/Mamluk (1174–1516 CE) sherd, implying that considerable time may have passed between the likely seismically induced roof collapse and the later wall collapse, which was not clearly seismic. This leaves open the possibility that one of the mid-8th-century CE earthquakes or a later shock damaged el-Lejjun.

de Vries et al. (2006:196) suggested that Umayyad abandonment of the northwest tower was probably triggered by further major collapse. In the North Gate, de Vries et al. (2006:207) documented full-scale destruction in layers above third-earthquake debris and post-earthquake occupation layers containing Late Byzantine and Umayyad sherds. Subsoil/tumble in C.9.008 (north room), C.9.009 (south room), and C.9.005 (stairwell) bear ample witness to the destruction of the rooms, perhaps in the Umayyad period. Although Late Byzantine sherds occurred in post-Stratum layers of the North Gate, if the third earthquake corresponds to the Inscription at Aeropolis Quake (before 597 CE), an approximate and conservative terminus post quem of ~600 CE can be inferred. While the terminus ante quem is the end of the Post-Stratum III gap (1918 CE), the earthquake most likely occurred much earlier.