I went around Santorini asking locals and tourists how much they really know about the geologic dangers on the island. A young local boy told me “The old people tell us [stories of the island] and we forget, so we make up our own stories.” He had a decent idea about the island but didn’t know a lot about the active volcano nor the active fault line on Santorini. His friend confessed to me that he knew nothing about the island and felt as if he didn’t need to know. He explained “I work and sleep here, nothing else.”
Santorini is one of the most explosive volcanic islands in the Aegean Sea. Though it is said to be dormant, a dormant volcano can be triggered at any time causing unforeseeable damage. The question is not “when will the volcano erupt?” but “what are the hazards associated with the island?”(1) Many people who visit Santorini, and even the people who live there, are not aware of all the hazards.
During the Crisis Period of 2011-2012 there were many events that raised concern among scientists monitoring the volcano. There were earthquake swarms along the Kameni fault line; all were less than or equal to a 3.5 magnitude at 2-4km deep. There were many earthquakes each day and some days even reached 50 earthquakes per day. There were changes in hydrothermal activity as the sea temperature increased by 4 degrees Celsius. The amount of carbon dioxide released increased from 12 tons/day to 36 tons/day along with the ground inflation of 20mm/yr. Everyone thought the volcano was about to erupt at any given moment; yet no one ever did anything about halting tour visits to the volcano.
My professor visited Santorini for the first time during the Crisis Period and was not aware that the volcano was predicted to erupt at any given time. She even visited the active volcano and was never warned by anyone of the hazards and risks associated at the time. It wasn’t until she arrived back home and started research that she discovered that Santorini was speculated to possibly have a small eruption.
The major hazards associated with Santorini are not only volcanic eruptions; but earthquakes, and landslides, (along with a few I will not cover such as tsunamis, flooding, subsidence, and ballistic projectiles). The goal of this post is to educate future explorers and locals of Santorini the risks and hazards of this island.
I asked Teuma, a tourist from Australia if she was aware that there is a highly-active major fault line that goes through Santorini. Her reply, “No! Where is it?”
There are two major fault lines that pass through Santorini. One by Oia, the Colombos line and one by Fira, the Kameni line (figure 1). One local, known as “The Architect” built a hotel (the Architects House, figure 2) on the colombos fault line without knowing there was a fault line on that location.
For the last 100 years earthquakes have been thought to cause greater damage on Santorini than volcanic eruptions. The last major earthquake was in 1956 on the island Amorgos, northeast of Santorini. The earthquake had a magnitude 7.5 and an aftershock 13 minutes later on another island, Ios, with a magnitude 7.2. This earthquake caused a tsunami that had a height of 20-25 meters at a Amorgos and hit Crete with a height of 1-2 meters. 326 buildings were destroyed on Santorini (1). (Read more on Tayler’s blog “The tragic events following the 1956 earthquake”)
I asked Teuma if she knew what to do if an earthquake were to occur here. Her reply, “You stay still and hide under a stable doorway”. Which is not wrong, but you would want to get away from the caldera rim first. And hopefully there would be a warning beforehand to give people time to flee.
During an earthquake on Santorini, you would not want to be close to the caldera rim due to its high and steep slopes. During an earthquake this part of the island is susceptible to landslides, making the locations around the rim extremely dangerous.
Most tourists I talked to knew that Santorini was highly subjected to landslides. Their reasoning was that there are landslides all over the world, so why wouldn’t Santorini have them as well. Likewise, the locals knew about landslides and told stories of people getting hit in the night and dying; “Huge blocks of lava that have been loosened from ash layers sometimes roll down, especially at night, and kill people or smash into houses” (Ross and Seebach 2) After talking to a few people I realized most locals and tourists believe geologic hazards happen at night; Landslides, and all other geologic disasters, happen at anytime of day.
Landslides are a collapse of land due to gravity, added weight, water, earthquakes, or volcanos. There is a higher risk for landslides on steep sided slopes, especially where there are buildings to add weight (see figures 4 and 5). Santorini has an extremely high occurrence of landslides due to all of these characteristics previously mentioned along with that this island is composed of loose, unstable pyroclastic rocks. Although, where most buildings are located there is a lava flow beneath to make the land a little more stable (figure 7).
Landslides typically occur where previous landslides have occurred as well. There are two types of landslides that occur on Santorini, rock fall and slump. Rock fall is exactly like its name; it occurs when loose rocks fall. Places that have this type of landslide are Oia, under Fira, Red Beach, and Cape Plaka. The second landslide is slump and is when loose material slides down a cliff just like when you “slump” in your chair. The architects house, caldera rim, port and Oia all have problems with this type of landslide.
I asked a local “Did you know that this island is composed of many different volcanoes?” He replied, surprised, “No! I just know the one in the middle [that] we can see.” Most locals I have run into give almost identical replies and believe that the one and only volcano on this island is the one in the middle that we can see, Nea Kameni. Yet, little know that this entire island is a big battle scar of many different volcanoes that once ruled the earth. Small, monogenetic (single occuring) volcanoes become inactive and claim territory on other parts of the island like little pimples on a much bigger volcano; the entire island is the caldera’s rim to a volcano that seeps down far beneath the ocean. The scary part?-It could have an eruption so big as to wipe out the entire island as well as affecting surrounding islands and countries.
In the last 400,000 years there have been 12 major eruptions, several minor eruptions, and 4 caldera collapses (2). Despite the fact that there is risk for volcanic eruptions, the probability of a major eruption happening is not likely. The max probability of a caldera collapse, like the Minoan eruption, is 1 in 20,000. The most probable is one like the 1924 eruption, a hydrovolcanic eruption, and the most destructible is a sub-plinian eruption. However, there is one major disclaimer; scientists cannot predict the next volcanic eruption until a few hours before an eruption.
The biggest volcano that could erupt here is a caldera forming eruption, which is the most explosive out of all eruption types. The last eruption, in 1613 B.C., was the event that caused the Minoan people to flee and sunk most of the island. (For more history about the geography of the island see Emily’s blog post “Field Trips Through Time: A Geographical History of Santorini”)
The most destructible eruption to likely occur would be a sub-plinian eruption. This type of event has a highly explosive eruption with gas-rich felsic rocks, large eruption columns and mushroom clouds, pyroclastic flows, surges, and extensive fallout. This eruption is extremely hazardous and would most likely kill anything in its path.
The most probable eruption to occur on Santorini anytime soon would like the eruption in 1924, a hydrovolcanic eruption (see figure 8). This kind of eruption happens with other hydrothermal activities and produce a great amount of steam to be thrown up into the air at a height of 3.2 km pushing other rocks from previous eruption up with it (2).
After talking to 8 locals and 8 tourists, along with many others not recorded, I found a pattern. Everyone knew of Nea Kameni and have either visited in the past or planned to visit soon. One tourist, Ilacqua, informed me that the tour guides told her and her family that the volcano is going to erupt within the next 5-10 years, which isn’t true. Scientists cannot predict when a volcano will erupt that far in advance.
I have learned the locals play a big game of telephone and spread false information. It’s like what the first local said that the elder tell stories, over time they forget, and later make up their own stories to tell their friends. False information is spread through the locals and the locals share this with the tourists.
Overall, I was surprised at how much certain tourists knew. Teuma knew a lot about volcanoes and explained that she is fascinated by them and has traveled to many others across the world. Though, I did run into a number of people who had absolutely no idea there was an active volcano on Santorini.
Almost everyone knew about the landslide hazards on Santorini. Each person I chatted with was happy to be reminded of this hazard; they were aware but didn’t really ever think about it. Personally, I have a hunch that there are many tourists here that are not aware of the landslide hazard; my theory is I have not run into them because they’re hiding in their landslide-prone hotels built into the side of steep slopes.
Most locals and tourists were not aware of the major fault line that passes through Santorini. in fact, most locals were very alarmed and surprised when I explained and showed them where the fault lines were on a map (figure 1). They knew earthquakes happened on Santorini but did not know why.
One of my classmates during class said “The longer we stay on this island the more we learn how dangerous it is to be here.” Santorini is a very dangerous and hazardous volcanic island. My advice to you; be careful and be aware of your surroundings. Do not stay in hotels that put you at risk during one of these geologic disasters; hotels with infinity pools, right on the rim, by the fault line, built on top of unstable material, built by landslide scars, etc. Before you come, make sure Santorini is not having another crisis period or changes in the activity at the active volcano. Keep in mind, it could potentially blast at any moment.
1. Bell, K, 2013, Tectonophysics: Submarine evidence of a debris avalanche deposit on the eastern slope of Santorini volcano, Greece
2. Friedrich, W, 2009, Santorini- Volcano, Natural History, Mythology: Denmark, Narayana
3. Figure 1&7 Geosphere http://m.geosphere.gsapubs.org/content/2/5/253.figures-only
4. Figure 3 The Tragic Events Following the 1956 Earthquake by Tayler Smith
5. Figure 8, unknown source