Archaeoseismic evidence at Khirbet Yajuz is documented across multiple excavation areas and is expressed primarily through collapse deposits, fallen arches, and fire-related debris. In Area B, a small chapel dated by a Greek mosaic inscription to 508 CE was sealed by a destruction layer consisting of ash and collapsed arches lying directly above the mosaic floor. Khalil (1998) records “a ca. 15 cm thick layer of ash and collapsed arches,” with associated pottery dated to the Byzantine–Umayyad transition, and suggests that “perhaps the destruction of the chapel was caused by the 749 AD earthquake.” Comparable structural failure is recorded in Area C, where a mill and wine-press complex included large rooms with multiple internal arches; these arches collapsed onto plastered floors, “probably due to an earthquake” (Khalil, 1998).

Additional archaeoseismic indicators are reported in Area E, where collapsed vaulted arches and irregular paved floors were attributed to an earthquake dated to the middle of the 8th century CE (Savage et al., 2001:448, possibly relying on communication with Lufti Khalil). These damaged features were subsequently reinforced, dividing walls were added, and a leveling layer of hawar was applied over the pavement, indicating post-destruction repair rather than simple abandonment. Although stratigraphic mixing was observed, with materials from earlier periods reused during repair, the collapse itself is consistently assigned to the Umayyad period. Savage et al. describe this sequence as earthquake destruction followed by Abbasid-period rebuilding, reinforcing the interpretation of a mid-8th-century seismic event.

Dating of the destruction relies on termini derived from both ceramic and numismatic evidence. Khalil and Kareem (2002) demonstrated that a pottery assemblage from post-earthquake loci dates from the second half of the eighth century into the tenth century, providing a terminus ante quem, while two copper coins dated to the early Abbasid period provided an even earlier terminus ante quem. When this terminus ante quem is combined with the terminus post quem provided by the Byzantine–Umayyad pottery found beneath the collapses, the seismic destruction at Khirbet Yajuz converges to a mid-eighth century CE date.