It may surprise you to hear that some of the most popular vacation spots across the world were once the most dangerous places man could ever set foot on. Keep reading to learn more about how this country we are staying in holds more secrets than it lets on…
On our way to Santorini we took a huge ferry the size of a cruise ship across the deep blue, island-scattered waters of the Aegean Sea! The Aegean Sea hosts many extraordinary features drawing millions of tourists each year: unique beaches, vibrant sunsets and elaborate churches, some of which we have gotten to visit so far…but the true mystery of the Mediterranean lies “Under the Sea.”
Beneath the royal blue Aegean Sea lies a hard rock layer called the “crust” of the earth. But unlike pizza crust, this crust stretches all across the entire earth and is cut up into irregular shapes that hover over the mantle—a layer of molten rock. What most people don’t know is that these pieces of crust, also called tectonic plates, (someone was hungry when naming these features), are constantly moving at about the rate that your fingernail grows.
However, not all of these plates are moving in the same direction. They can actually collide and shove underneath each other, which is exactly what happened—and is still happening—to the Aegean Plate. This process is called subduction, and the places where this happens are called subduction zones. The African Plate has thrust underneath The Aegean Plate, causing massive cracks in the crust allowing for magma from the mantle to flow up to the surface…the beginnings of a volcano. This diagram shows something called a cross-section, a view that is like cutting a piece of cake and looking at of the layers from the inside (okay maybe I’m the hungry one). It’s great at helping you understand what’s going on under the surface.
Out of the 150+ islands in the Aegean Sea, only five are volcanic. Why is that? Well, it turns out that all five of these islands sit on these enormous cracks, or faults, and are made up of the magma from below. Due to the curved shape of the African Plate, it first started subducting under The Aegean Plate in the west forming the volcanic center of Methana, then Milos, then Santorini (where I am right now!), then Nysiros, and finally, Kos. The pink teethed line is where the African plate is being subducted underneath the Aegean Plate, and the arrows are pointing in their direction of motion.
This is a map of the Santorini Volcanic Group, created by our very own assistant professor, Alex Huff. It is comprised of three different major volcanoes: Christiana, Santorini, and Kolumbo, which have all been created due to magma squeezing through the colossal fault.
Can you spot the two islands in the distance? This photo was taken by our TA, Jenna Chaffeur, on week one when we drove to a beach called Kabia where we both learned and enjoyed the sun! Christiana is the oldest in the Santorini Volcanic Group, clocking in at around 650,000 years old. It was the first volcano to form along this fault. Even though it looks like two separate islands in this picture, it is actually one large one mostly submerged underwater with only these two small peaks sticking out.
Welcome to Santorini! Santorini is the second volcanic complex to form along this fault line. However, Santorini is unique in that it is home to not just one, but over ten different volcanoes scattered across the five islands making up the Santorini complex: Therasia, Aspronisi, Nea Kameni, Palea Kameni and Thera, where we are staying. The first volcano formed around 645,000 years ago. The most catastrophic eruption we are aware of occurred during The Late Bronze Age in 1530 BC. This explosion was so powerful that a huge chunk of the island collapsed into a cavity in the earth that is now plugged and covered with water. This huge bay is actually the cavity, or caldera, where it fell in.
Sea anything? This next volcano, Kolumbo, is the most dangerous since it erupted most recently in 1650 AD and is still classified as an active volcano. But as you can see, it’s actually entirely underwater! Volcanologists are monitoring this seamount closely to remain aware and prepared if it does erupt again.
The earth has not always looked the way it does today. It has a magnificent, catastrophic past that has literally shaped the land into what it is today. Without the plate tectonics and volcanism in the Aegean Sea, Santorini would not be here today!
This is a cross section of this underwater volcano, Kolumbo. It shows just how much is going on under the ocean that we don’t know about! Did you know that we know less about our oceans than the planet Mars? Crazy!
Andrei, Mihai, 2015, The Thinnest Layer of the Earth:
http://www.zmescience.com/other/science-abc/thinnest-layer-earth/ (Accessed June 2019).
Huff A.E., Nomikou P., Skinner L.A., and Hooft E.E.E., 2019, Preliminary Geologic Mapping of the Santorini Volcanic Group Submarine Geomorphology Using Planetary Geologic Mapping Methods, The University of Athens, 1:25,000 Scale.