The view from the Temple of Poseidon, Cape Sounion, Greece. Photo by Jospeh Koudelka/Magnum


Poseidon’s wrath

Vanished beneath the waves in 373 BCE, Helike is a byword for thinking about disaster, for ancients and moderns alike

by Guy D Middleton + BIO

The view from the Temple of Poseidon, Cape Sounion, Greece. Photo by Jospeh Koudelka/Magnum

One night nearly 2,500 years ago, the people of Helike, a city in the northern Peloponnese, were in their homes. Perhaps they were winding down with a glass of watered wine or already sleeping after spending the day about their business in the bustling town. Some had been busy at the market, selling or buying the produce from the local farms or purchasing goods from further afield. Some might have visited the famous Temple of Poseidon, as worshippers or priests of the cult, or trained in the gymnasium. Others were engaged in usual city business, the day-to-day civic and political life of Helike. This night, though, would be their last.

As they slept, a terrible earthquake struck the region, toppling buildings and killing the inhabitants. Then, in a second calamity, the city was swallowed up by a giant wave. The inhabitants disappeared. A recovery party of 2,000 men sent from neighbouring cities found no bodies. The nearby village of Bura was destroyed too.

The story of the destruction of classical Helike in 373 BCE rippled out through the Greek lands. When it was recent history, Aristotle (384-322 BCE) wrote of it in his Meterologica, a book not only about the atmosphere and weather, as we would expect, but also more generally about what we could term Earth processes, including earthquakes and tsunamis. Helike was remembered and written about for centuries by Greek and Roman authors. But as the centuries turned and the coastline shifted, the location of the once-great city was forgotten. The search for this city has captivated modern archaeologists for more than 50 years.

Exploring what happened at Helike involves looking at different types of evidence, including ancient texts, archaeological evidence and geological study. This search enables us to learn not only about this fatal disaster, bringing us closer to the people of the past, but it can also help reveal the way in which the ancient Greeks and Romans thought about how their world worked.

Greece is a common victim of earthquakes and tsunamis; it is the most seismically active part of Europe. In the past 10 years, there have been eight earthquakes of magnitude 6+. The Athens earthquake of 1999 killed 143 people (magnitude 6) and the 1953 Kefalonia earthquake killed 476 (magnitude 7.2). Since 1950, 22 earthquakes in Greece have also generated tsunamis. On 30 October 2020, there was a magnitude 7 earthquake and tsunamis struck the island of Samos and the Turkish coast. At Samos, the tsunami ran up onto the land to a height of 1.8 metres. In 1956, a tsunami hit the island of Amorgos, with a run-up height of up to 25 metres.

In the 20th century, our understanding of these phenomena is founded in a sure scientific basis through a century of geological work. Alfred Wegener’s theory of continental drift, proposed in 1912, led eventually to the development of the idea of plate tectonics, that the Earth’s surface was in motion, and then to its confirmation through observation and mapping of the ocean floors after the Second World War, especially the publication of the Tharp-Heezen map of the Atlantic in 1977. We know that earthquakes are caused by slipping and thrusting at faults, areas where the Earth’s tectonic plates meet. When this happens underwater, the motion causes the displacement of water, which results in tsunamis. Landslide, either above or underwater, is another mechanism that creates tsunamis and is a common result of earthquakes. The Amorgos tsunami was caused both by the displacement of the sea floor and by undersea landslides.

Our perception of natural catastrophes is nowadays informed by science, the news, by documentaries, novels and the ever-popular genre of disaster movies, all of which provide us with ideas about, and images of, disaster. The ancient Greeks and Romans had their own traditions about disasters from the sea, which were passed down through the generations.

Perhaps the first description of a tsunami comes from Homer’s Iliad, written down in c700 BCE. Homer tells us that the Greeks had built a mighty wall to protect their ships, which were pulled up onto the beach. After 10 years of siege, the Trojan hero Hector was killed and Troy sacked. The victorious Greeks boarded their ships and left. Then Zeus, Apollo and Poseidon decided to erase all traces of the Greek wall – Apollo turned the rivers against it, Zeus brought constant rain, and Poseidon ‘the Shaker of Earth, bearing his trident in his hands, was himself the leader, and swept forth upon the waves all the foundations of beams and stones, that the Achaeans had laid with toil, and made all smooth along the strong stream of the Hellespont, and again covered the great beach with sand, when he had swept away the wall’. What prompted this divine cleansing of the landscape? According to the story, when the Greeks had built the wall, they had failed to make the proper sacrifices to the gods – and, while the wall lasted out the war intact, the gods eventually destroyed it.

Another ancient Greek myth, written down and preserved for us in a collection of stories called the Library of Greek Mythology, ascribed to the 2nd-century BCE scholar Apollodorus, also concerns a disaster from the sea. In the story of Perseus and Andromeda, Perseus, ‘arriving in Ethiopia, which was ruled by Cepheus … found the king’s daughter Andromeda exposed as prey to a sea monster; for Cassiopeia, the wife of Cepheus, had claimed to rival the Nereids in beauty … The Nereids were enraged by this, and Poseidon, who shared their anger, sent a sea-flood and a monster against the land …’ The story of Perseus and Andromeda was an ancient and popular one; the rescue is depicted on a painted Corinthian pot of the 6th century BCE and even on a Pompeian fresco centuries later.

These stories were not mere fantasy. The details have their origins in the observation of real natural processes – earthquakes and floods, as well as coastal inundation caused by waves or tsunamis. Even heroes, giants and monsters had at least some of their roots in the discovery, observation and display of unusual ancient animal bones, which could end up stored in temples. Such natural phenomena had to be accommodated and understood by people individually and within their shared culture and history. One way in which they could be viewed was through a religious lens.

The philosopher Democritus (c420 BCE) suggested, according to Sextus Empiricus, that gods had been created in ancient times because ‘men were frightened of celestial phenomena such as thunder and lightning … and imagined that the gods were responsible for these things’ – and for the Greeks generally ‘the whole … conception of the world was influenced by religious ideas’. So it is not surprising that earthquakes, floods and rogue waves were explained by divine action and references to the relationships between gods and mortals. The connection between earthquakes and the sea is made explicitly through the sea god Poseidon. Poseidon was worshipped from at least the Late Bronze Age (c1600-1200 BCE) until the later days of the Roman Empire – a span of more than 1,500 years.

The city was submerged so deeply that only the treetops in the sacred grove of Poseidon were visible

Reports on these natural phenomena are not restricted to myth. They are also found in the works of the earliest classical historians. Herodotus, writing in the later 5th century BCE, is remembered as the historian of the wars between the Greeks and Persians, but his work includes fascinating details of the habits and traditions of various peoples, and speculations on the natural world, including the source of the Nile. Herodotus tells us that after the Greek victories in 479 BCE, at the battles of Plataea and Mycale, the Persian general Artabazus escorted king Xerxes back through northern Greece to the Hellespont and across into Anatolia. The people of Potidaea, a city on the north coast of the Aegean, revolted against the Persians, and Artabazus decided to settle the matter and moved against them, putting the city under siege. After three months, Herodotus tells us, something unusual happened:

there was a great ebb-tide in the sea which lasted for a long while, and when the foreigners saw that the sea was turned to a marsh, they prepared to pass over it into Pallene. When they had made their way over two-fifths of it, however, and three yet remained to cross before they could be in Pallene, there came a great flood-tide, higher, as the people of the place say, than any one of the many that had been before. Some of them who did not know how to swim were drowned, and those who knew were slain by the Potidaeans, who came among them in boats. The Potidaeans say that the cause of the high sea and flood and the Persian disaster lay in the fact that those same Persians who now perished in the sea had profaned the temple and the image of Poseidon which was in the suburb of the city. I think that in saying that this was the cause they are correct.

This is a description of a tsunami: the sea retreated, exposing the land, and then flooded back in much higher than usual, drowning those exposed. In this case, Potidaea was saved by the sea from destruction by a human enemy, rather than destroyed in a disaster. The people of the city explained the event in terms of divine retribution for a sacrilegious act by the Persians, an explanation that Herodotus agreed with. Perhaps the story of the delivery of Potidaea by a great wave had become a popular one among Greeks in the period after the Persian wars. Recently, a team of researchers studying the landscape near ancient Potidaea have found plausible evidence of the tsunami in core samples taken from the region, which contain pottery and marine shells that could have been carried inland by the wave.

At the end of the 5th century, the Athenian historian Thucydides wrote of the Peloponnesian war, which he participated in as a general. In book three of his history, he tells us of a joint Peloponnesian army that set out to invade Attica in 426 BCE, but which retreated because of a spate of earthquakes. Years before, in 464 BCE, the Spartan slave class, the Helots, had seized the moment to rebel when a powerful earthquake struck Sparta. This time, the earthquakes were accompanied by tsunamis in at least two places in Greece, which Thucydides described:

About the same time that these earthquakes were so common, the sea at Orobiae, in Euboea, retiring from the then line of coast, returned in a huge wave and invaded a great part of the town, and retreated leaving some of it still under water; so that what was once land is now sea; such of the inhabitants perishing as could not run up to the higher ground in time. A similar inundation also occurred at Atalanta, the island off the Opuntian-Locrian coast, carrying away part of the Athenian fort and wrecking one of two ships which were drawn up on the beach.

Then, some 50 years after Orobiae and Atalanta, Helike was destroyed. Helike was an old and important city, situated in a fertile delta on the north coast of the Peloponnese between the Selinus and Cerynites rivers on the southern shore of the Gulf of Corinth, around 150 km west of Athens. It was the leading city in the Achaean League, a confederation of city-states, and was for centuries a major centre for the worship of Poseidon – Homer mentions ‘the offerings many and gracious’ brought to the ‘Earth-shaker’ at Helike, while archaeologists have found traces of a sanctuary dating back to c700 BCE. The only contemporary source surviving is Aristotle, who says very little except that there was an earthquake and a wave. The next source we have is another historian, Polybius (c200-118 BCE), who noted that Helike had been ‘engulfed by the sea’. But later sources tell the story in more detail.

The historian Diodorus Siculus (c80-20 BCE) described how an earthquake struck the Peloponnese at night and killed many people, especially at Helike and Bura. The survivors faced a still greater danger, when ‘the sea rose to a vast height, and a wave towering even higher washed away and drowned all the inhabitants and their native lands as well’. He emphasised the enormous scale of these twin natural disasters, writing that ‘never in the earlier periods had such disasters befallen Greek cities, nor had entire cities along with their inhabitants disappeared as a result of some divine force wreaking destruction and ruin upon mankind’. This was three centuries before his own time.

The Greek geographer Strabo (c64 BCE-c23 CE) preserved some snippets from two earlier sources on the disaster. He cited the contemporary Heracleides as saying that ‘the submersion took place by night in his time, and, although the city was 12 stadia distant from the sea, this whole district together with the city was hidden from sight.’ It was Heracleides who added that the 2,000 men sent by the other Achaeans to help were unable to recover any bodies from Helike. And Eratosthenes, he wrote, described how ‘he himself saw the place, and that the ferrymen say that there was a bronze Poseidon in the strait, standing erect, holding a hippo-campus [a mythical creature, half-horse and half-fish] in his hand, which was perilous for those who fished with nets.’

In the 2nd century CE, the travel writer Pausanias also told the story of Helike. According to him too, an earthquake and a giant wave swallowed up the city, its buildings and inhabitants. The city was submerged so deeply that only the treetops in the sacred grove of Poseidon were visible. He reported that in his time nothing remained to be seen of the city on land, but that some remains were still visible underwater. Later, Aelian (c175-235 CE) added a further detail, that five days before the earthquake ‘all the mice and martens and snakes and centipedes and beetles and every other creature of that kind in the town left in a body by the road that leads to Cerynea’. The people of Helike were amazed, but did not know why the animals left (Aelian believed that mice and martens would flee before the collapse of a building). He also tells us that 10 Spartan ships anchored at Helike were destroyed.

The sources, from the contemporary Aristotle and Heracleides to the much later Pausanias and Aelian, agree that Helike was struck by both a devastating earthquake in which many died, and that the city was ruined and submerged. The city remained partly visible underwater for some centuries, but eventually vanished. Since the general location of Helike was never lost, it has seemed obvious that it lay somewhere under the sea between the mouths of the Selinus and Cerynites rivers. In the 1950s, the Greek archaeologist Spyridon Marinatos began a search for the city, both on land, scanning aerial photographs, talking to locals about the landscape, and setting up a project to sonar-scan the seabed where Helike was thought to be. The lure of finding an ‘intact’ classical city, a time-capsule potentially still containing many of its treasures – possibly even the great statue of Poseidon – was strong. Despite a valiant attempt, Marinatos was unsuccessful. But he left the suggestion in his 1960 article in Archaeology that the city might actually turn out to be buried under the land rather than the sea. In 1861, a coin minted in Helike had been found in the area, which offered possible support to this theory.

In 1988, the members of a new Helike Project, having found nothing under the sea, began to drill boreholes on shore in the plain between the Selinus and Cerynites. Between 1991 and 2002, they drilled 99 to an average depth of 16 metres. At nine locations, they followed up with excavation. This time, the team found material of the classical period – pottery, walls, roof tiles and coins. They found traces of marine microfauna and a gravelly soil that could have been laid down by a giant wave. Helike had been found – or at least some tiny parts of it.

One local told about a vineyard that was originally next to the sea but only a few years later was 90 metres inland

But the team leaders Dora Katsonopoulou and Steven Soter were still not certain that their evidence was sufficient to prove that an earthquake and tsunami really did destroy the city. In a 2011 article in the international journal Geoarchaeology, they stated: ‘while the historical evidence for the earthquake and tsunami in 373 BCE is strong, evidence based on stratigraphy and archaeological excavation is merely suggestive’.

The region where Helike was situated is prone to landscape change of various kinds. The Helike fault separates mountains on one geological block to the south from the delta in the north on another. Earthquakes result in the rising of the mountains and the subsidence of the delta. One local told Marinatos about a vineyard that was originally next to the sea but only a few years later was 90 metres inland. It is possible that the southern part of the block was being forced down and the northern part, the coastline, was being forced up. At the same time, the rivers Selinus and Cerynites have occasionally changed their courses – sometimes because of uplift, causing flooding, and they are also constantly laying down sediment. Earthquakes can also cause soil liquefaction, in which areas of land in the region have been known to disappear. It is possible that a combination of earthquakes and tsunami, uplift and subsidence, and soil liquefaction ruined and then ‘swallowed up’ the city. Subsequent changes to the landscape have since buried it further. However, secure evidence on the ground for a great tsunami still remains elusive.

An alternative theory was proposed in 2020 in an article in The Holocene by Ioannis Koukouvelas of the University of Patras and colleagues, including Katsonopoulou. They suggest that, rather than being submerged by a wave from the sea, Helike might have been flooded from the landward side. This might sound bizarre at first, but the idea is based on real examples of rain and flood events in the region. In the early 20th century, for example, a natural dam had formed on the Krathis river, creating a lake 3 km long. Then, in January 1914, the dam burst, causing a metre-deep flood some 13 km in length. Studying the topography and hydrology of the region, and the evidence for past landslides, they propose that the 373 BCE earthquake caused dams to form in the Katourlas Valley and the Selinus River, which then gave way in flood events. Perhaps the killer wave was not a tsunami after all. Could contemporaries or later sources have misunderstood what happened? Was the story elaborated and then passed on? Or have we misunderstood something?

Plato’s philosophical works the Timaeus and Critias could help. These are the dialogues that recount the Atlantis myth, which is part-utopian fantasy and part-political allegory. The story of the fictional Atlanteans’ fall from grace was intended as a lesson: the Athenians should remember their past virtue and successes and beware of becoming too arrogant and bellicose. Plato wrote that:

There was an island … larger than Libya and Asia combined; from it travellers could … reach the other islands and from them the whole opposite continent … on this island of Atlantis had arisen a powerful and remarkable dynasty of kings, who ruled the whole island and many other islands as well and parts of the continent … At a later time there was earthquakes and floods of extraordinary violence, and in a single dreadful day and night … the island of Atlantis was … swallowed up by the sea and vanished.

In his Commentary on Plato’s Timaeus (1928), the classicist Alfred Taylor thought that the description of the destruction of Atlantis was ‘pretty certainly suggested to Plato by the occurrence of the same thing on a lesser scale in his lifetime. The tidal wave which destroyed the Achaean cities of Helike and Bura in 373 BCE … accompanied by a violent earthquake’. Later both Phyllis Forsyth in her Atlantis: The Making of Myth (1980) and Richard Ellis in his Imagining Atlantis (1999) also raised Helike as a possible source of inspiration for Plato, though Forsyth thought that a link to the prehistoric Thera eruption and Minoan Crete might be part of the story too.

But what is often left out when the Timaeus is quoted is that it also says the virtuous Athenian soldiers, who had just defeated the imperialistic Atlanteans, were ‘swallowed up by the earth’ at the same time as the island sank, which seems harder to explain. This fate could be related to the idea that a good death is a divine reward. It is also possible that Plato’s combination of a city and soldiers being swallowed up both by sea and earth recalls the story of Helike, though we should expect poetic licence and not a witness statement. The name Atlantis could have been inspired by the island of Atalanta, which, as mentioned above, was also struck by a great wave. These contemporary events are a much more likely inspiration for Plato than any distant memory of the eruption of the Thera volcano and its possible effects on Late Bronze Age Crete more than a millennium earlier.

‘The disaster was occasioned by the anger of the gods at those who had committed sacrilege’

The Atlanteans were punished for their desire to conquer foreign lands and enslave people excessively, and were defeated by the virtuous Athenians. A similar theme of divine retribution – or justice – permeates the ancient explanations for earthquakes and tsunamis. As mentioned, the Potidaeans and Herodotus thought Poseidon responsible for the deaths of the sacrilegious Persians. Poseidon had caused the tsunami in judgment for Persian actions. We should not dismiss Herodotus or the Potidaeans as particularly credulous, since even today many people understand, explain and make sense of disasters through the lens of religion, including many victims of the Indian Ocean tsunami of 2004.

Several sources record the idea that Helike’s citizens brought about their own destruction when they prevented a group of allied Greeks from Ionia from worshipping Poseidon at their sanctuary. Pausanias explained how ‘the wrath of Poseidon visited them without delay’. Two proofs that Poseidon was responsible, Diodorus noted, were that ‘first, it is distinctly conceived that authority over earthquakes and floods belongs to this god, and also it is the ancient belief that the Peloponnese was a habitation of Poseidon’. Such attributions of cause made sense in the general worldview of the time.

Strabo combined the idea of divine intervention with what we would see as a more scientific explanation, that the sea was raised up by an earthquake. Thucydides had given a similar reason for the great waves of 426 BCE, perhaps in a conscious contrast to Herodotus. He stated that:

The cause, in my opinion, of this phenomenon must be sought in the earthquake. At the point where its shock has been the most violent the sea is driven back, and suddenly recoiling with redoubled force, causes the inundation. Without an earthquake I do not see how such an accident could happen.

By his time, some three centuries after the event, Diodorus tells us that the destructions of Helike and Bura had ‘been the subject of much discussion’ and that:

Natural scientists make it their endeavour to attribute responsibility in such cases not to divine providence, but to certain natural circumstances determined by necessary causes, whereas those who are disposed to venerate the divine power assign certain plausible reasons for the occurrence, alleging that the disaster was occasioned by the anger of the gods at those who had committed sacrilege.

Given the frequency of earthquakes in Greece, it is hardly surprising that they had attracted the attention of thinkers stretching back to the beginnings of the Greek philosophical tradition – and in a sense they can be understood as part of the development of this more ‘scientific’ approach to the world. The Roman poet Ovid (43 BCE-17 CE) incorporated Pythagoras’ (c570-495 BCE) theories of change into his poem the Metamorphoses – putting a long speech into his mouth; everything changes, he says:

I’ve seen the ocean turn to dry land; and sea shells often lie far from the shore; and on a mountain top is found a rusty anchor centuries old … In deep quakings of the earth rivers burst out or, drying, sink from sight [or shift to flow a different way] … The sea encompassed once Antissa and Tyre and gleaming Pharos: none are islands now. Leucas, the early settlers used to tell, was once a promontory; now the waves surround it. Zancle too, they say, was joined to Italy until the ocean tore their boundary apart and straits between severed the land. And should you ask for Buris and Helice, once cities of Achaea, they lie beneath the waves; sailors still show the tilted towns and sunken battlements.

Aristotle’s section in the Meteorologica on earthquakes and their cause begins by summarising the views of three men, Anaximenes (c586-528 BCE), Anaxagoras (c500-428 BCE), and Democritus. Anaximenes thought that earthquakes happened during droughts or heavy rains, and associated them with the drying or wetting of the earth. Anaxagoras suggested that earthquakes happened when air tried to rise from below the earth but was prevented by moisture – rain-soaked ground. Democritus, on the other hand, thought the earth filled with water not air and argued that the escape of excess rain from underground caused earthquakes, as did the influx of water when a space dried out.

For Aristotle, wind was the underlying cause of the destruction of Helike

Aristotle disagreed with all of these theories, suggesting that Anaximenes’ ideas did not fit with what was observable about where and when earthquakes happened. Aristotle ventured his own explanation for earthquakes and tsunamis: wind. He drew on several strands of observational evidence, for example the locations of the most violent earthquakes, the existence of subterranean noises and the swelling up and bursting of land and eruption of winds to prove his theory. Tsunamis, he argued, were caused by:

an opposition of winds … when the wind which is causing the earthquake is unable quite to drive out the sea which is being driven in by another wind, but pushes it back and piles it together till a large mass has collected. Then, if the first wind gives way the whole mass is driven in by the opposing wind and breaks on land and causes a flood.

For Aristotle, wind was the underlying cause of the destruction of Helike, and this conclusion was based on his observation and knowledge of previous events and phenomena. Earthquakes and tsunamis could be seen as evidence of natural processes and not caused (at least directly) by gods. His explanation was followed by the Roman philosopher-poet Lucretius (c100-50 BCE) in his The Nature of Things.

Diodorus and Strabo hint at a lively interest among people of antiquity in understanding earthquakes and tsunamis, and we could add other sources to our discussion, such as Pliny the Elder and Seneca, in Roman imperial times. Some scholars even composed catalogues of earthquakes in ancient Greece, such as the one by Demetrius of Callatis (3rd century BCE), mentioned by Strabo. Sadly, these have not survived, but they would have been important repositories of earthquake observations and information in ancient times. Besides speculating on their causes, we know also that ancient Greeks and Romans sometimes dreamed of earthquakes and tsunamis. The dream-interpreter Artemidorus (c200 CE) tells us that the rocking of the earth signified the rocking of a person’s life: the more severe the trembling, the worse the diagnosis, although for debtors or émigrés they could be positive signs of release from difficult circumstances.

The ancient world was not so different from today in that its people experienced and sought to understand natural disasters brought on by earthquakes and tsunamis. They did so in ways that were influenced by their milieu – by their traditions and education, and by their conversation and curiosity. These natural disasters were part of the story of the developments of religion, cultural norms and social behaviour, and also of the development of what we see as rational or scientific thinking.

Helike and Bura stand out in the sources because of the apparent severity of their destruction. However, the archaeological research carried out in the Helike region shows that it was not completely abandoned in 373 BCE. There are later destruction layers and coins minted shortly after 373 BCE, the remains of a Hellenistic temple, as well as Roman remains, including a major road. It could be, as some of Helike’s researchers think, that the calamity was not as great as the texts suggest and that people continued to live in the fertile delta. Perhaps the destruction of the two towns became a popular story and a literary trope symbolic of a terrible natural disaster, much as Pompeii is for us today. Perhaps it even became something like an exemplar or case study for the educated to think about particular Earth processes, part of an intellectual exercise, like explaining the source of the Nile.

What exactly happened to ancient Helike and Bura is not clear, despite more than 50 years of scrutiny by archaeologists and geologists. But we can be sure that there was a catastrophe of some kind that destroyed the city and killed many inhabitants, which was sufficiently powerful to make Helike a byword for disaster; we know enough about the region to believe that it is plausible. Contemporary calamities such as the Indian Ocean tsunami can show us the real human experience – the terror, the cost in lives, and the aftermath – of these ancient disasters, as well as pointing to the way people respond to such events, and even how they might eventually recover from them.