Santorini is an immensely popular tourist destination, and for good reasons. One of the most powerful volcanic eruptions in recorded history created the dramatic landscapes that make this island one of the most beautiful in the world. Around 3600 years ago, during the Bronze Age (~1600 BCE) at the height of Minoan civilization, a massive eruption emitted vast quantities of magma and rock, causing collapse of the island’s central region and forming Santorini’s vast caldera. The distinctive layers on the caldera walls reveal the island’s nearly 2-million-year eruptive history.
A southward view of the caldera wall showing layers of volcanic rocks erupted during the past 400,000 years. The white buildings cascading down the top of the slope are in the main town of Fira. The hill in the background (Mesa Vouno) is made of ancient metamorphic rocks (schist and marble) that were the base the volcanoes built upon. We hiked to the top of Mesa Vouno to see ruins of the ancient Hellenistic/Roman/Byzantine-era city of Thira. I took this photo from our last-night hotel in Imerovigli. Although the previous three nights we stayed in a B+B on the back side of Fira, we splurged on the last night and stayed in a caldera-edge B+B. See map below for locations.
Santorini’s tectonic setting
This map shows the tectonic setting of Santorini, which is part of the South Aegean (or Hellenic) Volcanic Arc (red dots) that extends almost 500 km (300 miles) from mainland Greece to Turkey. The Hellenic trench is where the African plate subducts beneath the Aegean subplate of the Eurasian plate. [See my last post for more information about this region and the geology of Crete: https://landscapes-revealed.net/crete-is-rising-during-earthquakes-and-rivers-are-cutting-down/.]
The subducting African plate causes melting. This magma rises through the Aegean subplate and creates the volcanoes (red triangles). Santorini is the next volcano east of Milos; it is the most active volcano in the arc. The red lines crossing the arc are fault lines associated with volcanic activity—they act as conduits for magma to rise to Earth’s surface. Grey arrows indicate directions of movement of the Aegean subplate (north of the trench) and the African plate (south of the trench). Figure from http://www.photovolcanica.com/VolcanoInfo/Milos/Milos.html.
Trip details
Our trip to Santorini was part of the self-guided excursion we organized through Cretan Adventures: https://www.cretanadventures.gr/en/our-tours/self-guided-hiking-crete-santorini/. The first part ended in Heraklion on the northern coast of Crete. From there, we took a two-hour fast ferry to Athinios Port in Santorini. The trip included three nights in a B+B in Fira; we added a fourth night at a B+B in Imerovigli, on the edge of the caldera (see map below).
We choose the following activities: (1) visited Akrotiri town that was buried during the 1600 BCE eruption and walked to Red Beach; (2) took a wooden boat to Nea Kaimeni island and hiked to the island’s craters; (3) visited Perissa (with black sand beach) and hiked up Mesa Vouno mountain to ancient city Thira ruins and down to Kamari town; (4) did a wine/food pairing at Anhydrous winery in Fira; (5) walked the caldera edge from Fira to Oia; (6) ate lots of delicious Greek food. The public bus system transported us to most parts of the island. Although cruise ship passengers travel in large groups, we mostly managed to avoid them.
Cretan Adventures provided us with an excellent geo-tourism map of Santorini (see reference below). I derived most of the information about Santorini’s volcanic history from this publication.
Views of the caldera and smaller islands
Santorini is not a single volcano but an amalgamation of many volcanoes that have erupted during the past 1.6 million years. While traveling around the island, visitors can see volcanic rocks of many different ages. The Minoan eruption is only the most recent caldera-forming event. Geoscientists have found evidence for at least three older calderas that formed 180,000–21,000 years ago.
This view of the caldera is westward from our hotel in Imerovigli. The most prominent island is Nea Kaimeni, the currently-active volcano that has built up since the caldera formed around 1600 BCE. Barely visible behind Nea Kameni is the somewhat older Palea Kaimeni. A smaller island behind Palea Kaimeni is Aspronisi Island that is part of the Santorini caldera. The thin strip on the upper left side of the photo is the southernmost part of Santorini around Akrotiri. The island on the upper right side of the photo is Thirasia, another piece of the Santorini caldera.I also took this close-up view of Nea Kaimeni from our lodging in Imerovigli. Note the harbor with several wooden boats. The boat trip we took from Athinios Port anchored in this cove. From there we hiked to the island’s summit to see fresh black lava and craters. This volcanic island has formed since the powerful caldera-forming eruption, beginning in 1570. The most recent eruption was from the central crater in 1950. The long island on the right is Palea Kaimeni, where boats are docked to allow passengers to swim in a hot spring. It is an older volcano that erupted in 46–47 and 726 CE. The island on the upper left is Aspronisi, part of the caldera wall. In the distance are the Christianes Islands where eruptions began in this region a little over 2 million years ago. The Santorini complex of volcanoes began about 1.6 million years ago, in what is now the southern part of the island near Akrotiri.We are standing next to one of the craters on Nea Kaimeni, where we had a great view of the surrounding caldera walls, with their “icing” of white buildings. The winding path up the caldera wall goes to Fira, the main town. See the next photo for closeup of this area. A closer view of the caldera walls below Fira taken from our boat on the way back to Athinios Port. Most of volcanic layers beneath Fira were erupted during the past 360,000 years. The path up the caldera is the route between the Old Port and Fira. I visited Santorini once before in 1989, 36 years ago. At that time, I arrived via ferry at the Old Port where visitors had to either walk up the 500+ steps with their luggage or hire a donkey. Today, ferries arrive at the new port (Athinios) where buses and taxis wait to carry visitors to their hotels or excursions. Our ferry from Crete carried hundreds of people, most without luggage, so they were just visiting the island for a short excursion before returning to Crete.
The Minoan eruption
The volcanic eruption in ~1600 BCE is the main creator of Santorini’s present-day landscape. It buried the town of Akrotiri in ash and created the breath-taking caldera. I’ll write a separate post about this exceptional event.
I took this photo as we were returning from Nea Kaimeni to Athinios Port where the wooden boats dropped us off to be carried by coach back to Fira. Notice the two coaches on the road descending to the port. This photo shows a good exposure of the volcanic layers deposited during the Minoan eruption. It’s the thick, whitish section at the top of the caldera, immediately below the white-colored buildings.Here is a closeup of the Minoan tuff, which can be found throughout the island at the top of the volcanic sequence of layers. Lava is coherent magma that flows down a volcanic slope. In contrast, tuff is a type of pyroclastic rock made of mostly volcanic ash. Pyroclasts are hot particles that get ejected from vents during explosive volcanic eruptions. They are deposited via air falls or from turbulent flows. The Minoan tuff contains ash-sized particles and larger pumice fragments (the dark pieces). The clasts at the top of this exposure may have been reworked by flowing water. This exposure is near the ruins of Akrotiri.
Red Beach and Oia
The oldest part of Santorini is located at the southern end of Santorini. This “Akrotiri Volcanic Complex” was active from about 1.6–0.5 million years ago. Most people go to the south end of the island to visit Akrotiri town that was buried in ash during the Minoan eruption. Popular Red Beach is just a short walk from the ruins.
Red beach is a good place to see one of the older volcanoes. The beach is below one side of the Mavrorachidi Cinder Cone that formed around 500,000 years ago.Here is a closeup of cinders at Red Beach. The cinders are pieces of pumice, another type of pyroclast.
One of the most significant volcanic complexes is the stratovolcano of Thera, which erupted in four distinct periods: 360,000–180,000 years ago, 60,000–40,500 years ago, 40,000 years ago, and around 1625 BCE—the famous Minoan eruption. Volcanic products emitted from the Thera volcano are the rock layers visible on the main caldera walls near Fira town (see photos above).
Another significant volcanic complex is Therasia/Oia, which was active at the same time as Thera. The last activity in that complex was 21,000 years ago. I took this photo of the caldera walls at the north end of Santorini while we were walking on the trail between Fira and Oia. Oia is the town with white buildings on the left side of the photo. See the Santorini map above for the location of Therasia island. It is disconnected from Oia but is part of the caldera wall.
Fira at night
Astonishing views of the caldera walls and Santorini buildings are not limited to the daylight hours. Here are a few night shots.
Left-side photo. From our B+B on the backside of Fira we walked upward through narrow pedestrian alleyways to the caldera edge for dinner. Along the way were attractive buildings and flowers, at this time with a full moon above. Right-side photo. Our favorite Santorini wine is Assyrtiko, an indigenous white wine that ages well. This 2019 Grande Reserva by Santo Wines was luscious and a great accompaniment to our fish dinner at Santorinia Tavern on the caldera’s edge.Watching sunsets is a favorite Santorini activity. This view is from our table at Santorinia Tavern on the caldera edge in Fira.
Epilogue
I’ll do one more post about Santorini that focuses on Minoan culture, the Minoan eruption, and the ruins that remain. Meanwhile, here are two other photos from Santorini that I like.
Left-side: Georgia O’Keefe-esk photo of a small church at Oia. Right side: interior of Roka Restaurant in Oia.
Reference
Geo Tourism in Greece, A journey to our exceptional geoheritage, 2013, GEO-01 Santorini: Geotourism, volcanological and excursional map of Santorini and of the contemporary volcano, by Staridas Geography.
What an absolute delight to read this. Thank you, Karen, for your ever-interesting posts. I visited Santorini (and Crete) in 2011, and marveled at the multiple colors and textures of rock, but of course understood very little about how/when they were created. What a joy it must be to “read” them as you do.
Many thanks, Karen. I am now at an age (93) whan travel is more limited – therefore your posts make me feel as though I am still traveling and the geological information is pricelesss.!!
I would love to repeat all the excursions you listed. I visited Santorini April ’89 and walked up! That photo of you and Jay with the caldera walls (incredibly interesting) and ‘icing of white buildings’ is fantastic. Truly amazing what occurs over time!
So funny that we were both there in 1989 — me in July, you in April, when it must have been quite tourist-free in those years. A good month to return! Thanks for comment.
What an absolute delight to read this. Thank you, Karen, for your ever-interesting posts. I visited Santorini (and Crete) in 2011, and marveled at the multiple colors and textures of rock, but of course understood very little about how/when they were created. What a joy it must be to “read” them as you do.
Thanks Diana! It is a joy to “read the rocks” — and a joy to have people like you enjoying the posts.
Many thanks, Karen. I am now at an age (93) whan travel is more limited – therefore your posts make me feel as though I am still traveling and the geological information is pricelesss.!!
Thanks Mary! I appreciate your comment very much.
I would love to repeat all the excursions you listed. I visited Santorini April ’89 and walked up! That photo of you and Jay with the caldera walls (incredibly interesting) and ‘icing of white buildings’ is fantastic. Truly amazing what occurs over time!
So funny that we were both there in 1989 — me in July, you in April, when it must have been quite tourist-free in those years. A good month to return! Thanks for comment.