The AD 365 Ammianus tsunami in Alexandria, Egypt, and the Crete ca. 365 fault and tsunami

Abstract

The traditional interpretation of a legendary, though controversial, fourth century text of Ammianus Marcellinus is that an earthquake-generated tsunami hit Alexandria on 21 July 365. The causative earthquake is usually associated with the Aegean Arc, and it has been modeled through elastic dislocation of the up to 9 m uplift of Crete which occurred in ca. 365. A rather steep, intra-plate fault was inferred, and this predicts a regional tsunami, with about 0.6-m-high waves just offshore Alexandria. However, modeling does not reproduce the tsunami polarity clearly described by Ammianus, first major retreat of the sea and then flooding; this polarity can better be explained by a slump-generated tsunami in the eastern part of the Nile Delta. On the other hand, analysis of historical and archaeological evidence excludes the possibility of a major destruction of Alexandria in 365. The possible explanation for this puzzle is that Ammianus mixes at least two events: a slump-generated, locally impressive tsunami to east and a regional tsunami from Crete. None of these events produced significant destruction in Alexandria, which was protected by fortification walls and by an islet to the north, and in addition, it was exposed mostly to longshore waves of the 365 tsunami. These results do not mean that Alexandria has not been affected by other historical tsunamis and that the modern town is not exposed to earthquake and tsunami hazards.

Appendix 1 Selected historical texts

The Appendix summarizes four critical texts referring to the 365 tsunami. First, the Ammianus text, which is the main source of information for the tsunami, but its reference to Alexandria is problematic, and it may report marginal only effects in this town. Second, a Festal Letter by St Athanasius, head of the Alexandria Church, which specifies the source of the tsunami from the east and does not mention significant damage in Alexandria. Third, a later text, reporting a tsunami with marginal effects in Alexandria, which was saved by a miracle of St Athanasius, and hence excludes any major destruction. Fourth, one of the very few ancient texts which mention Alexandria in relation to the 365 events and which reports an exaggerated number of victims. However, this text is duplicating and exaggerating Ammianus information. For details and additional information, see Stiros (2020).

Ammianus MarcellinusXXVI 10, 15–19, Loeb Classical Library edition.

http://penelope.uchicago.edu/Thayer/L/Roman/Texts/Ammian/26*.html

15 While that usurper of whose many deeds and his death we have told, still survived, on the twenty-first of July in the first consulship of Valentinian with his brother [in 365], horrible phenomena suddenly spread through the entire extent of the world, such as are related to us neither in fable nor in truthful history.

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.

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 [i.e. shells] 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 marvellous sights.

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.

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.

Comments:

• 1. The last sentence does not indicate two miles inland, but a site at the second milestone (hewn mark of mileage of a main the road) near Methoni and the whole sentence 19 should be translated as

“Other great ships, driven by the mad blasts, landed on the tops of buildings (as happened at Alexandria),and some ships were found inlands, as was the case with a Laconian ship I saw decaying since long, at the second milestone of the road near the town of Mothone”.

• 2. Ammianus text does not mention damage or death toll Alexandria, only vessels on top of roofs, which it may indicate only marginal effects in the wider Alexandria area.

Athanasius Festal Letter XXVII.

(translation from Syriac into Greek in the 4th to 5th c., Henry 2012, p. 182)

http://www.ntslibrary.com/PDF%20Books/Athanasius%20Select%20Writtings%20and%20Letters.pdf; page 1189/1339.

In this year [365] …. Then, an earthquake happening on the twenty-seventh of Epiphi the sea returned from the East, and destroyed many persons, and much damage was caused.

Comments.

• 1. Athanasius was the head (Bishop, Patriarch) of the Church in Alexandria. Should a significant calamity had affected his See, it would be awkward to have been ignored.

• 2. Twenty-seventh of Epiphi corresponds to 21 July in the Egyptian calendar, starting on the 25th of each month.

John Bishop of Nikiou.

A 7th c. Bishop in Egypt and historian.

Chronicle, LXXXI (LXXXII) (translation by P. de Jenevois).

18…. And how the ocean tide rose to Alexandria to such a height that it would have submerged the city had not the holy Athanasius the Patriarch checked it by his prayers.

19. And in the days of this abominable (emperor Valens) there was an earthquake in the city of Nicaea where the holy council had been held. For the sea rose against it and overwhelmed it. 20. And in those days also a man named Tatian was appointed prefect of Alexandria [Prefect Tatian, c. April 370].

21. And in those days there appeared a miracle through the intervention of the apostolic S. Athanasius, patriarch of Alexandria.

22. When the sea rose against the city of Alexandria and, threatening an inundation, had already advanced to a place called Heptastadion, the venerable father... raised his hand to heaven...

23. And after these words of the saint the sea returned to its place ... Thus the city was saved...”

Comment.

Implies marginal flooding, only in Heptastadion (Figs. 2 and 4c). Such a report for a miracle which saved Alexandria excludes the possibility of flooding and destruction of this town.

Georgious Monachus, 9th century text.

https://ia802702.us.archive.org/16/items/georgiimonachic00boorgoog/georgiimonachic00boorgoog.pdfp. 560–561.

(translation by Kelly 2004)

In these times there was a great and fearful earthquake, so that in Alexandria the sea retreated and ships were found lying as if on dry land. People came to look at the wondrous sight. But the sea returned beyond its normal extent and drowned 50,000 people. Some of the ships moored there were covered by the waters and others, found in the river Nile, were thrown inland, up to 180 stades [about 3.5 km].

There was destruction in Crete, Achaea, Boeotia, Epirus and Sicily, and many ships were thrown 100 stades on to mountainsides. There was worldwide devastation including in Africa and the Brettanic isles.

In some seas, including the Adriatic and the Aegean, waters retreated as though forming a wall, and dry land appeared. Ships were found floating, and those resting on the bottom were raised again by the revival of the waters. There were continuous earthquakes including at Germe in Bithynia.

Comments

• 1. The words “and the Brettanic isles” were silently removed from most modern studies referring to Georgious Monachus because they were interpreted as British Isles, and hence indicating non-credibility of the only ancient text which reports major destruction at Alexandria. However, as noticed by Henry (2012) and Stiros (2020) they are likely to indicate the Brac Isles in southern Croatia.

• 2. This text shares common sources with that of Ammianus, exaggerates the damage but reflects non- independent information.

• 3. The number 50,000 in ancient Greece indicates “too many”.