Ancient sources indicate that Sidon was affected by the Posidonius Quake. According to Strabo, citing Posidonius, “a city situated above Sidon was swallowed up, and nearly two-thirds of Sidon itself was engulfed too, but not all at once, so that no considerable destruction of human life took place.” The report further notes that the effects extended across Syria and even into parts of the Aegean, though these wider phenomena may reflect conflation with other events. Seneca the Younger , also drawing on Posidonius, reiterates that Sidon was “swallowed by the sea.”

The description that the city was engulfed “not all at once” is noteworthy and may point to a progressive ground-failure process rather than instantaneous collapse. Such behavior is consistent with a large, slow-moving landslide or widespread liquefaction event affecting coastal or alluvial deposits. In this scenario, sections of the urban fabric could have gradually subsided or slumped toward the shoreline, creating the impression that the city had been “swallowed,” while allowing time for partial escape and thus limiting loss of life, as explicitly noted in the ancient account.

The date of the Posidonius Quake remains uncertain. Ambraseys (2009) places it in the second century BCE and estimates a date around 199 BCE. Most earthquake catalogues list 199 or 198 BCE, although some assign the event to 525 BCE, a date for which the evidentiary basis remains unclear.