Crete earthquake and tsunami of 365

The fullest account is by Ammianus Marcellinus. A little after sunrise, after heavy and repeated thunder and lightning, the earth shook and the sea drew back, laying bare its bed, so that people wandered through the shallows left behind, gathering fish by hand; then the water came back in a great surge, fell upon islands and coasts, levelled countless buildings and drowned many thousands. At Alexandria ships were left on the roofs of houses, and near Mothone (Methoni) in the Peloponnese Ammianus himself saw a ship lying almost two Roman miles from the shore, falling apart with age. At the end of the 6th century Alexandria still marked the anniversary each year as a “day of horror”.

Geologists link the event to an uplift of western Crete by up to about 9–10 metres: radiocarbon dating shows that corals on the island’s coast were lifted clear of the water in a single push. Modern estimates of the magnitude range from about 8.3 to 8.6. Excavations record destruction around this time in many late antique cities of the eastern and southern Mediterranean, notably in Cyrenaica: at Cyrene, where skeletons of victims were found under fallen masonry, and at Ptolemais. An epitaph from the necropolis of Cyrene, dated by its lettering to the second half of the 4th century, commemorates a mother and her son, Demetria and Theodoulos, killed by an earthquake.

Historians debate whether the written sources describe a single catastrophe or merge several earthquakes of 350–450. Libanius and the church historian Sozomen seem to have blended the great earthquake with lesser ones and read it each from his own standpoint: for the pagan Libanius the earthquakes were the Earth’s mourning for Julian, who had died two years earlier, while the Christian Sozomen placed the flood at Alexandria in Julian’s time — in his reign or while he was still Caesar — as a sign of God’s displeasure with the apostate emperor.