Two later Byzantine chroniclers, Theophanes and George Cedrenus, record a destructive earthquake affecting Beirut and, by implication, much of the Lebanese littoral between 347 and 349 CE. Both accounts describe widespread destruction, noting that most of the city collapsed. The chronological indicators in their narratives constrain the event to between 25 March 347 and 8 September 349 CE. Grumel (1958) dated the earthquake to 348 CE.

Some older catalogues associate this event with a possible tsunami, but neither source explicitly mentions one. Even so, because the reported damage comes from a coastal city, a tsunami remains a plausible though unconfirmed possibility.