Alexandria Tsunami, Egypt – 365 AD

A tsunami generated by an earthquake in Greece destroyed Alexandria – Harbor of Alexandria, Egypt

In the summer of 365, the port of Alexandria in Egypt was hit with a powerful tsunami that traveled across the eastern Mediterranean from a sea-floor earthquake near Turkey. Italy, Greece, and other places were also hit but the heaviest blow fell on Alexandria. It was in direct line with the direction that the wave took and it was one of the first places to feel the impact of this wall of water traveling at more than 500 miles an hour. As is always the case with large tsunamis, when the wave reaches shallow water, as it would in the harbor of Alexandria, it first rises to a great height, then recedes back out to sea before coming back a second time with renewed force. The people of Alexandria, unaware of the nature of tsunamis, walked out on to the new beach to collect fish. The seabed had been laid bare and all kinds of sea life could be seen. People wandered freely far out from land gathering fish and they were caught in the returning wave. As many as 50,000 people were killed either from the returning wave or in the destruction that followed on shore.

Ships were picked up by the wave as it reached the harbor and they were thrown some distance on to land. In some cases, they landed on roofs. The strength of the tsunami was evidence that the earthquake that caused it was a major one, probable at least 8 on the Richter Scale. Sediment cores taken from the harbor in recent years enabled geologists both to date the event and to establish the probable location of the earthquake that caused it. Alexandria does not lie on a geologic fault like so many other places in the eastern Mediterranean so it has no record of earthquakes and the occurrence of a tsunami is so unlikely that the port authorities of Alexandria gave no thought to it.

Royal palaces and the obelisks that were known as Cleopatra’s Needles were built along the shore and one of the ancient wonders of the world, Pharos Lighthouse, stood on the outermost extremity of land around the port. Alexandria, founded by Alexander the Great more than 300 years BC, was the biggest commercial and cultural center of the whole Greco-Roman world in 365. It was from here that the Roman Empire’s main supply of wheat was shipped. The Nile Valley was the best wheat-growing region in the empire. It had also been the seat of the world’s oldest university, located next door to the biggest if not also the oldest library of antiquity.

Powerful earthquakes are known to have occurred previously in the same location that originated Alexandria’s tsunami. One of these earlier quakes was so powerful that it created a hole, deep into the sea floor. Not every earthquake gives rise to a tsunami but, whenever the level of the seabed is changed over a significant distance, the displacement of water that it causes creates a special wave, a tsunami. That was what happened when the level of the seabed was changed in the 2004 Indonesian earthquake.

The power of the initial release of energy sends the tsunami across the ocean at more than 500 miles an hour. In the deeper parts of the ocean the huge displacement of water is barely visible on the surface and it has little effect on ships in the same place. Once it approaches land, however, it changes dramatically. The lower part of the wave slows down as it encounters the friction of the seabed in shallower waters while the upper part increases in height as the same volume of water enters shallow water. As it rises in height it creates a vacuum that sucks water away from the shoreline, leaving as much as two miles of the seabed exposed. This was the condition that caught Alexandrians off guard. They had never before encountered a tsunami. Today we know that the withdrawal of water is the prelude to a sudden and fast destructive wave crashing on to the shore.

Saint Jerome, whose original work led to the famous Latin Vulgate Bible, was so moved by the destruction of Alexandria in 365 that he thought the world was returning to its original chaos. Like other great scholars, both of that time and from earlier years, he knew that Alexandria was one of the greatest cultural and literary centers of the world and he hoped that its famous library would be preserved. Hundreds of thousands of manuscripts were stored there. Euclid’s work in mathematics was there as was also the work of another famous Greek mathematician, Eratosthenes, the man who was the first to calculate the length of the earth’s circumference. The Greek version of the Old Testament, known as the Septuagint because it was assumed that seventy Jewish writers wrote it, was compiled in Alexandria. It was the version widely used by Paul and others in the first century of Christendom before other translations of the Old Testament were available. Unfortunately, Jerome’s wish was not to be, not because of the tsunami but rather on account of the many conflicts that were centered on Alexandria as different religious and military powers fought for ascendancy there. The library dated from the times of the Ptolemaic rulers of Egypt. Over the years it suffered major damage from accidental fires. In 47 BC, during his military campaign in Egypt, Caesar set fire to ships in the Port of Alexandria and the fires spread to the library.

In 391 riots were instigated by fanatical Christians because of the collections of heretical documents that were stored in the library. Their actions caused serious damage. Over the two hundred years that followed, the library was restored to a condition close to its former greatness as manuscripts were added and lost ones replaced with copies. Then, in 641, the Caliph of Baghdad, in another moment of religious fanaticism, ordered the burning of the entire library. Archaeologists have found what they believe to be the former site of this library. A Polish-Egyptian team excavated parts of Alexandria and discovered what looked like lecture halls or auditoria. They found thirteen of these lecture halls, sufficient space to accommodate five thousand students.

The question most-frequently asked is, how did this, the greatest collection of books in the ancient world, came to an end? In fact, as archeological research has revealed, there were two libraries in Alexandria, the royal one and a daughter library. Both were within the city of Alexandria. The Royal Library was destroyed in the aftermath of Christianity becoming the official religion of the Roman Empire. The daughter library survived a bit longer but it too was destroyed before the year 400. One thing about this library’s demise is known: when Arabs conquered Egypt in 642, there was no library there.

In the thousand and more years that followed this event, the underlying threat of another tsunami never disappeared because the tectonic forces that caused the tsunami in 365 continued to operate as they had always done. The people of Alexandria had no understanding of these forces and so the memory of what had happened remained as an inexplicable event. Fortunately, in relation to this risk of another tsunami, Alexandria ceased to exist as a seaport and important city in the centuries that followed the conquest of Egypt. The new authorities had little interest in a major seaport and decided to make their capital on a site that is now the city of Cairo. The waterways that connected Alexandria to the Nile gradually silted up and maritime trade dropped off. People who were connected with the sea trade left and, by the time that Napoleon’s ships arrived there around the year 1800, Alexandria was little more than a small fishing village.

Napoleon’s visit created a new interest in the sea on the part of Egypt’s rulers. Within twenty-five years, the city was once more a busy seaport as new canals were dug, linking the port with the Nile. With French assistance, warehouses, docks, and homes were built. By 1840, Alexandria’s population had risen to 250,000. Today it is a city of more than six million and the danger of another tsunami like the one that arrived in 365 still remains.

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