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F - 165 : More Powerful than 45'000 Nukes

This summer we are going to see many abandoned and destroyed ancient cities. Our sailing route through the Aegean is full of them. As we see again in the Ukraine, it is man who wipes out towns. Nobody can live in peace if the bad neighbor does not let you. Reminds me of an old Roman saying, “Si vis pacem, para bellum”. If you want peace, prepare for war. I wish we had helped the brave Ukrainian people more in the past.

Circular Santorini or Thera lies just south of the Cyclades before the open Sea to Crete

On our route, there is one exception though. Occasionally, there are natural disasters which exceed our capacity for destruction. Right in the middle of the Aegean, there is the Greek Island of Santorini or Thera. Here, 3’650 years ago, around the year 1’646 BC, a mighty volcano blew up with the power of 45’000 Hiroshima bombs and completely destroyed the island. Entire sections were blown away. The sky filled with more 80 - 90 cubic kilometers of gas, ash and debris and erased the summer the following year. A 40-meter-high Tsunami devastated anything that stood in its way.

The Bronze Age Town of Akrotiri was berried under 40 meters of pumice and ash

The explosive eruption blew the island of Thera to pieces. What remained was a rim – even some of the rim evaporated. In 1867, miners in the island’s pumice quarry, the stone lighter than water, found ancient artefacts and walls 40 meters below the surface and alerted the authorities. First excavations were arranged soon thereafter which led to the discovery of Akrotiri, the “Greek Pompeii”. The earliest buildings date back to the 5th millennium BC. Due to lack of funds, proper excavations only started in 1967. They continue to this day and are likely to continue for a considerable time.

Minoan Style Fresco from Akrotiri showing a Port Town and Trading Ships

Turns out that Akrotiri was an important bronze age trading center involved in the ancient copper trade. Copper smelting and casting devices were found - so were many objects from Cyprus and Crete. Akrotiri was a much larger settlement than originally thought. It had many multi-floor houses, proper street, a drainage system and walls decorated with lively frescos showing everyday life. Unfortunately, I could not find out how many people lived in Akrotiri. Surprisingly also, there were no human remains found like in Pompeii nor any gold, silver or precious stones. It seems that Akrotiri's citizens had just enough time to abandoned town. The enormous number of filed pottery containers and complete sets of house hold furniture indicate that there was no time for packing. People only grabed their most valuable items. What happened to the citizens of Akrotiri is unknown.

Computer Simulation of the Tsunami triggered by the Thera Eruption

Whilst Akrotiri’s citizens may have escaped, people living on the shores of neighboring island and Crete were less lucky. The eruption triggered large pyroclastic flows into the sea which causes a Tsunami with a wave height of up to 40 meters. Most of the pyroclastic flows occurred on Thera’s south side. The Cyclades islands in the north were “only” hit by a 4-meter-wave. Tried to figure out how far a 40-meter wave would penetrate inland but my maps of Crete are not detailed enough to provide an answer. but I guess a far distance. This means that not only all Minoan port and fisher villages were destroyed but also a significant portion of the agricultural land on Crete’s north coast. It is estimated that 20’000 people were killed. Most of them by the Tsunami wave.

Crete's North Coast is rather flat - most Minoan Urban Centres were close to the Sea

The ash and volcanic debris spewed out into the atmosphere had an even bigger impact. Mount Tambora in Indonesia erupted in 1815 and ejected about 100 cubic kilometers of ash. and smoke and 100 tons of sulphate aerosols into the atmosphere. A summer without a sun and catastrophic harvest failures followed the year after. 1816 was the first time in human history that the fall-out from a huge volcanic eruption was measured and recorded. There are reports of snowfall in June from New England, massive harvest failures in Germany and England. Not only harvests failed. People also lost their livestock in the cold weather and the Mediterranean suffered from a Typhus epidemic in 1816 and 1817.

Distribution of Ash in Centimeters after the Eruption

The consequences of the Thera eruption must have been similar. There are no written records from 1646 BC but ice cores in Greenland and much tighter tree rings indicate very cold summers and much heavier snowfall all over the northern hemisphere. We know that the Minoan civilization collapsed around this time. Whilst there is no consensus yet as to whether the Thera eruption was the root cause, it becomes more and more likely as more research results come available. A government and an economy based on division of labor need agricultural surpluses to function. Without it, the edifice of civilization implodes.

On the Vulcanic Explosion Index (VEI), Thera was a 7 just

A bit smaller than the Tambora Eruption from 1815

The bronze age town of Akrotiri can be visited today. Despite the fact that excavation is still ongoing, the site is now protected by a large roof and an elaborate path leads through the site. Have not been there yet but friends tell me that the visit is an absolute must.

Volcanic eruptions on the level of VEI 7 or higher do not occur frequently. But every 100 or 200 years there is one. Site like Thera, Krakatoa, Mt St Helens or Mt Tambora need to be monitored carefully. Santorini is thus full of sensors which keep an eye on the new caldera in the centre that has formed since the explosion 3'650 years ago. The Thera volcano is in a state of low activity but that can change. When we visit Tholos Navtilos, the island in the centre, we will smell the sulphur and see the hot steam rising still today.

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