Possible Tsunami Waves which could reach the Coast within 15 - 20 min after a landslide
When writing the blog about our visit to the Aeolian Islands and researching how to climb Mount Vulcano. I found a piece on the internet warning about the danger of a future Tsunami in the Tyrrhenian Sea. Not having time to investigate, I put it aside to look at it a bit later. I vividly remember the pictures of a Japanese Coast Guard vessel in 2011 encountering a Tsunami a few dozen miles off the coast. It was a big, rolling wave but felt like a gentle swell – it lifted the vessel up and once it had passed returned it back to the normal sea level. It was a non-event for the Coast Guard crew. A few minutes later the same wave would wreak havoc on Japan’s eastern coast and destroy the nuclear power-plant of Fukushima.
The Marsili Ridge in the Tyrrhenian Sea - it was discovered in the 1920s
The article I found drew attention to the submerged volcano of Marsili locate halfway between Sicily and Naples. Marsili is young, only 200’000 years old and sits on the last remainder of the Tethys Plate which is slowly subducted under the European Plate – if I understood the Italian article correctly. The Marsili volcano is more than 3’000 meters high and its peak reaches as high as 450 meters below sea level. Apparently, its flanks are built from structurally weak volcanic material that could collapse almost any day. The internet piece has been published in 2019 and is probably alarmistic to attract attention. But am sure there is some truth to it. Marsili would not be the first volcano to collapse. Volcanic rocks like pumice can be very light and collapse under their own weight.
Shape of the Marsili Volcano on the bottom of the Tyrrhenian Sea
Provided Marsili collapsed and large parts of it came crashing down to the Tyrrhenian sea floor – dropping 2’500 meters – what would happen? The underwater land slide would displace water at very high speed and create a giant wave. The internet report estimated the size of the wave being catastrophic High enough to devastate the northern coastline of Calabria and Sicily. But I could not find any detailed research on this subject. The volume of the landslide would have to be modelled to get an idea of the amount of water displaced. It would then form a Tsunami wave which grows as it gets closer to shore. Sadly, I have not found any good research yet. Does anyone know more? I thus can’t say whether the risk is real or just fear mongering.
The flooded Santorini Caldera - in Antiquity the Island was called Thera
But we should take these risks serious and not forget that similar events eclipsed entire civilizations. When the volcano of Santorini blew up, it did not only destroy the island and kill its people. It also triggered a giant Tsunami which wreaked the ports of the Minoans and spew so much ash into the sky that it ruined several harvests. The already weakened Minoan civilization on Crete did not survive and faded from human memory. It was rediscovered in the 19th century only. Thanks to our global connectivity, today’s society is far more resilient and could survive such a shock. Tsushima is the best proof. But the death toll would still be considerable
Earthquakes in Italy since 1900 to today
Be it as it may, the Marsili volcano reminds us that plate tectonics in Europe are in full swing. One look at a map with earthquakes in Italy says it all. There is no single town on the peninsula which has not suffered at least once in its history from a tremendous earthquake. We all remember the destruction of the small Italian town of Amatrice in Central Italy in 2016.
The Amatrice Earthquake in Central Italy in 2016
Being on the AFAET is actually very safe. She would be the safest place to be if we were to hit a Tsunami. As the Japanese Coast Guard vessel we would experience a big and quiet swell – not more – provided we were at sea and not staying in a bay or a harbor.
The AFAET with her sturdy steel hull
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