Morhange et al. (2006b:91) reported that tectonic uplift affected the Lebanese coast during the 6th century CE (Pirazzoli 2005, Morhange et al., submitted). Subsequent geomorphological and marine-geophysical studies have refined this picture, revealing significant evidence for co-seismic coastal deformation linked to the major 551 CE Beirut earthquake. Elias et al. (2007) documented uplifted marine benches along the Lebanese coastline between Sarafand and Tripolis, including the area near Tabarja (~20 km northeast of Beirut). Their investigation showed that the lowest emergent bench (B1) was uplifted by approximately 80 cm in the 6th century CE. Offshore geophysical surveys revealed fresh west-facing fault scarps cutting across the otherwise smooth seafloor, which they linked to seismic slip on the newly identified offshore Mount Lebanon Thrust Fault system . Based on the extent of faulting, they inferred that ~100–150 km of the thrust ruptured in 551 CE, producing an earthquake with a moment magnitude (M_w) of approximately 7.5. The chronology of coastal uplift was established by Morhange et al. (2006a), who dated fossil vermetids on the uplifted benches to establish when they were last situated in the subtidal zone (close to mean sea level). These data, when combined with the structural evidence, strongly support attributing the uplift of ~80 ± 30 cm to the 551 CE earthquake.

Despite clear geological evidence for significant co-seismic uplift along the central Lebanese coastline in the 6th century CE and multiple textual reports of a tsunami associated with the 551 CE Beirut earthquake, sedimentological investigations at Byblos have revealed no trace of tsunami-related deposits. Carayon et al. (2011), who examined six sediment cores from Byblos — two taken from the northern harbor and four from the bay of El-Skhiny — as part of a broader reconstruction of the harbor’s geomorphic evolution, reported no evidence of tsunami-generated layers or sedimentary disturbances attributable to the 6th century CE seismic event. It is important to note, however, that the publication did not include core profile data, limiting the ability to independently verify the absence of tsunami deposits.