Atlantis - Third Part - Santorini eruptions

It was the eruptions of AD 19, 46–47 and 60 that created the island of Theia, ‘Divine’, now called Palea Kameini. The eruption of AD 60 was reported by Philostratus, together with the peculiar detail that the sea receded about one kilometre from the south coast of the island. This may have been associated with a tsunami, commonly produced by earthquakes focused on the seabed, and likely to occur during a submarine eruption.

In AD 726, Santorini experienced another major eruption. This was adjacent to Theia (Palea Kameini), produced a third island and threw ash as far as Macedonia and Anatolia.

In 1573 an eruption created the islet of Mikra Kameini to the east of Palea Kameini. In 1650 a series of earthquakes led up to a major submarine eruption off the north-east coast of Thera, forming a temporary island called Kouloumbos. Poisonous gases released during the eruption blinded or killed many Therans and their livestock.

Reconstruction of bronze age Thera

In the eighteenth century, Leychester reported that the new island had disappeared (eroded by wave action), forming a reef. According to other sources, the flames of the 1650 eruption were visible from Heraklion, and tsunamis swept among the Turkish ships beached on the island of Dia, close to the north coast of Crete.

For four years beginning in 1707 there were explosive eruptions of lava back in the caldera between Theia, now called Palea Kameini, and Mikra Kameini. The build up of lava created a new island called Nea Kameini: the eruptions of 1866–70 trebled its size. The King George I crater, formed at this time, is now 131 metres high. But for our story the main importance of this eruption sequence is that it attracted geologists and archaeologists to Santorini, where for the first time they recognized traces of a forgotten bronze age civilization.

There was a major explosion on Nea Kameini in August 1925 and the eruption that followed lasted nine months. 100 million cubic metres of lava poured out, joining Nea Kameini and Mikra Kameini and producing a lava dome. A further eruption in 1928 formed the Tholos and Nautilus craters. In 1939–41, the Nea Kameini craters were active again. In 1950 another explosion on the top of Nea Kameini led to the formation of the newest dome, Liatsikas, beside the King George I crater.

For the last two millennia a long series of volcanic eruptions in the Santorini island group is well documented. Cone after cone has been added to the centre of the bay, the rim of which is the outer edge of a much bigger crater than any that has been active in the last 2,000 years. Unless the process is interrupted by another caldera eruption, the bay will eventually be refilled with lava and Santorini will be one island.

The geology shows that before the caldera eruption of 1520 BC Thera had already been disembowelled by more than one earlier eruption and the bronze age island had a substantial South Bay occupying the southernmost third of the modern caldera.

This south west basin may have been formed during a caldera eruption before 54,000 BC. Another caldera eruption near Cape Riva in 18,300 BC created the north west basin, so there may have been a bay, or at least low ground, between northern Therasia and Thera during the Minoan period.

The volcanic peaks visible on Santorini in the Minoan period had developed over a million years, from several vents within a preexisting island group of non-volcanic origin. Mesa Vouno and Profitis Elias, for instance, stood above the waves of the ancient Mediterranean much as they do now, long before the volcanic cone complex was built. Monolithos and Platinamos too stood up from this ancient sea, as peaked islets of schist and marble.

In the bronze age, Monolithos was still a separate islet, but Mesa Vouno and Profitis Elias were already engulfed in the volcano which made a single ‘Greater Thera’, an island shaped like a huge fish head with its mouth gaping towards the south west.