Kehrberg-Ostrasz and Manley (2019:21) describe a tumble layer in Trench 400 of the East Wall of Jerash. After the dumping (405, 407, 411), “a sudden partial collapse from the face of the City Wall occurred, resulting in the distribution of six rows of facing masonry (406) in the main trench.” These facing stones “had fallen into neat rows, a little way from the base of the Wall,” and their untouched arrangement suggests they had “not been disturbed since the event.” Most stones “had vertical faces, and most had at least one dimension close to 0.45 m or 0.4 m, similar to the dimensions on the uppermost extant courses of the City Wall.” They conclude this tumble likely represents the collapse of the rear parapet of the city wall. Associated Byzantine pottery indicates the wall survived intact into the Byzantine period, and the collapse, they note, “may have been caused by an earthquake.”

Kehrberg-Ostrasz in Savage et al. (2003: 458) supports this interpretation, observing that a collapse of the wall “face down onto the western rocky slope already littered with residual rubbish” lay beneath Late Islamic and contemporary debris. Pottery and glass sherds below the tumble show that the destruction occurred “during the Late Byzantine period” and was “probably the result of an earthquake that was responsible for the destruction of other city buildings in the sixth century.”