The tin trade may have had Bronze age man discover the Americas and it was kept secret (by the Phoenicians kept their valuable tin ore mines a secret. So when the tin trade collapsed so did this globe spanning culture. So maybe “Atlantis” was the memory of tis bronze age era that collapsed?
You just don't miss a blowout of that size in the relatively small confines of the eastern Mediterranean. Ash deposits have been found as far away as Egypt and Turkey, and most Aegean islands have a charred layer of soil.
My parents were in the area (on my dad's WWII "victory tour") and visited Thera (modern Santorini). The island is just the surviving rim of an enormous volcanic crater (6-8 miles across), and they have a museum there with all sorts of neat stuff.