The tsunami of 365 CE: a disastrous tidal wave that destroyed the ports of many Roman cities in northern Africa.
In 365 CE, on the twenty-first of July, the southern shores of the Mediterranean were hit by a tidal wave – a tsunami – that was exceptionally violent. The Roman historian Ammianus Marcellinus writes about it. He mentions Alexandria in Egypt, where the royal palace vanished beneath the waves. Archaeologists have identified destruction on many other places: Sabratha, Lepcis Magna, and Apollonia. Tyre and Sidon are other plausible candidates: everywhere, those parts of the city close to the sea were swallowed. Although the cities survived, they had lost their ports.
A tidal wave starts with an earthquake. In 2008, geoscientists identified a fault west of Crete that slipped during a quake within the third quarter of the fourth century, which may have been the cause of the catastrophe.
The English translation of Ammian’s account is by J. C. Rolfe
[26.10.15] On the twenty-first of July in the first consulship of Valentinian with his brother, horrible phenomena suddenly spread through the entire extent of the world, such as are related to us neither in fable nor in truthful history.
[26.10.16] For a little after daybreak, preceded by heavy and repeated thunder and lightning, the whole of the firm and solid earth was shaken and trembled, the sea with its rolling waves was driven back and withdrew from the land, so that in the abyss of the deep thus revealed men saw many kinds of sea-creatures stuck fast in the slime; and vast mountains and deep valleys, which Nature, the creator, had hidden in the unplumbed depths, then, as one might well believe, first saw the beams of the sun.
[26.10.17] Hence, many ships were stranded as if on dry land, and since many men roamed about without fear in the little that remained of the waters, to gather fish and similar things with their hands, the roaring sea, resenting, as it were, this forced retreat, rose in its turn; and over the boiling shoals it dashed mightily upon islands and broad stretches of the mainland, and levelled innumerable buildings in the cities and where else they were found; so that amid the mad discord of the elements the altered face of the earth revealed marvelous sights.
[26.10.18] For the great mass of waters, returning when it was least expected, killed many thousands of men by drowning; and by the swift recoil of the eddying tides a number of ships, after the swelling of the wet element subsided, were seen to have foundered, and lifeless bodies of shipwrecked persons lay floating on their backs or on their faces.
[26.10.19] Other great ships, driven by the mad blasts, landed on the tops of buildings (as happened at Alexandria), and some were driven almost two miles inland, like a Laconian ship which I myself in passing that way saw near the town of Mothone, yawning apart through long decay.