Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Tuesday, October 31, 2023

A dangerous beauty

The Greek island of Thera -- often known by its Italianized name of Santorini -- is the southernmost of the Cyclades, an island chain in the Aegean Sea southeast of mainland Greece.  Like much of the region, it's a stunningly beautiful place.  In fact, one of Thera's names in antiquity was Καλλίστη -- "the most beautiful one."

[Image licensed under the Creative Commons Pedro Szekely from Los Angeles, USA, Santorini, Greece (38051518795), CC BY-SA 2.0]

The steep, rugged, rocky terrain, though, didn't happen by accident.  Thera and the other Cyclades formed because they sit near the margin of the Hellenic Subduction Zone, where the northern edge of the enormous African Plate is being shoved underneath the much smaller Aegean Sea Plate.  The result is the formation of an island arc, where the material in the subducted plate is pushed downward to a depth were it melts, and the blobs of magma rise toward the surface to create a chain of volcanoes.  (Most of the islands in the Caribbean, the Aleutians, and pretty much the entirety of the nations of Japan and Indonesia were formed this way.)

This makes it a dangerous place to live.  It was the site of the Minoan-era city Akrotiri, which became prosperous because of being a central port for the copper trade out of Cyprus (the Latin word for copper, cuprum, actually means "metal from Cyprus").  It was second only to Crete as a center of civilization for the Minoan Empire, and was famed for its art, especially elaborate and beautiful frescoes, pottery, and sculpture.  Many of the houses there had running water carried by bronze pipes, and geothermal heat.

The geothermal heat might have clued its residents in that something was going on underground.  All of the high times came to an end with a colossal eruption of the volcano just offshore in around 1600 B.C.E. 

[Nota bene: this is not what inspired the myth of Atlantis, despite the claims you see all over the place on the interwebz.  Plato made it clear that the legend said Atlantis was "west of the Pillars of Hercules" (the Straits of Gibraltar), somewhere out in the Atlantic (thus the name).  But... allow me to stress this point... Atlantis never existed.  Because it's a myth.]

Anyhow, the eruption of Thera not only destroyed pretty much the entire island, but blew an estimated forty cubic kilometers of dust and ash into the air, triggering atmospheric and climatic effects that were recorded by contemporaneous scholars in Egypt and China and draw comparisons from modern geologists to the Mount Tambora eruption of 1815 that caused "The Year Without A Summer."  The eruption generated a tsunami that devastated coastal cities all over the Mediterranean, including the Minoan city of Knossos on the north shore of Crete.  (The Minoan civilization limped along for another couple of hundred years after this calamity, but was finally finished off by a massive earthquake in 1350 B.C.E. that destroyed Knossos completely.)

Here's the thing, though.

The volcano off the coast of Thera is still active.

A paper last week in Nature Communications looked not at the enormous 1600 B.C.E. eruption, but a much smaller eruption in 1650 C.E.  The leadup to this eruption, however, was about as ominous as you could get.  People noticed the water in the seas off the north coast of Thera boiling and changing color -- and dead fish rising to the surface as well, cooked in situ.  Sulfurous gases wafted over the island.  This was followed by a cinder cone emerging from the sea, which proceeded to fling around molten rocks and ash plumes.

Then... boom.

The new research suggests that what triggered the eruption was a landslide, similar to what kicked off the famous Mount Saint Helens eruption of 1980.  In this case, though, the landslide was underwater, off the northwest flank of the volcano.  This landslide did two things -- it displaced huge amounts of water, generating a twenty-meter-high tsunami, and it took the pressure off the top of the magma chamber, causing it to explode.

The combination killed seventy people and hundreds of domestic animals -- horrible, but nowhere near what the island proved itself capable of 3,600 years ago.  The study found that the magma chamber is refilling at a rate of four million cubic meters per year, meaning with regards to subsequent eruptions -- to invoke the old cliché so often used in connection to active volcanoes and tectonic faults, it's not a matter of "if," it's a matter of "when."

Unsurprisingly, the people in the region seem unaware of the time bomb they're sitting on.  "Local populations, decision-makers, and scientists are currently unprepared for the threats posed by submarine eruptions and slope failures, as has been demonstrated by the recent 2018 sector collapse of Anak Krakatau and the 2022 [Hunga Tonga] eruption," the authors write.  "Therefore, new shore-line crossing monitoring strategies... are required that are capable of being deployed as part of rapid response initiatives during volcanic unrest and which enable real-time observation of slope movement."

It remains to be seen how this could help the almost two thousand people who currently live on the slopes of the island, many of them living in houses sitting on layers of fused ash deposited there during the 1600 B.C.E. eruption.  It's something we've seen here before; people like living in tectonically active regions because (1) the terrain is often dramatic and beautiful, (2) volcanic soils are good for agriculture, and (3) people have short memories.  If the last time things went kablooie was almost three hundred years ago, it's easy for folks to say, "What, me worry?"  (Witness the millions of people living near the terrifying Cascadia Subduction Zone, about which I wrote three years ago.  As well as all the people in the aforementioned countries of Japan and Indonesia.)

Anyhow, that's our rather ominous scientific study of the day.  The Earth is a beautiful and dangerous place, and nowhere does that combination come into sharper focus than the Greek islands.  Makes me glad I live where I do -- despite the cold winters, at least I don't have to worry about the place blowing up.


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