Petersen (2020:200–201) situates the Msaylḥa Bridge within a regional seismic context shaped by the 551 CE Beirut earthquake. He notes that the Roman coastal road between Beirut and Tripoli originally passed around Raʾs al-Shaqʿa (Byzantine Theouprosopon), but that “the AD 551 earthquake which ... destroyed Roman Beirut also destroyed the coastal road around the headland sending it crashing into the sea,” forcing later Byzantine and medieval traffic inland through the narrow Msaylḥa pass. The bridge, as the only historic crossing at this choke point, thus became a critical element of post-551 regional connectivity, and its strategic importance helps explain repeated phases of construction and repair.

The archaeoseismic evidence rests primarily on structural observations. Petersen (2020:202) showed photographic evidence for an earlier arch beneath later rebuilding of this bridge in medieval times. Petersen argues that “the structural history of the bridge indicates an early, probably Roman, origin,” and that “the collapse of the early vault [of the bridge] may be connected with the earthquake of AD 551.” The dating remains somewhat ambiguous: while the association with the 551 CE earthquake is contextually strong, the bridge experienced multiple rebuilding phases, and later historical activity at the site obscures a closed stratigraphic or epigraphic date. As a result, the attribution of the initial vault collapse to 551 CE relies on correlation rather than direct dating, leaving room for alternative or cumulative damage scenarios.

Figure 13.16 - Msaylḥa bridge (no. 9): detail of north abutment, showing remains of an earlier arch - (photo: A. Petersen, Feb. 2018) - Petersen (2020)