The year was 1956 when a family of seven children and their two parents were sailing on a boat in the Aegean Sea. The boat capsized in the caldera under Oia, Santorini. The seven children some how survived, but the parents unfortunately did not. There is now a church in the spot where this tragedy happened (Figure 1). The capsizing is thought to be from a tsunami that was triggered after an earthquake.
The July 9th 1956 earthquake was the strongest shallow earthquake to take place in this region during the 20th century (1). The main shock had a surface magnitude of 7.5, and the strongest aftershock took place 13 minutes later, with a magnitude of 7.2 (1). The epicenter (the point on the Earth’s surface where the earthquake begins) of the main shock was located 20 km south of the island of Amorgos, while the main aftershock was centered on the island of Ios (1) (Figure 3).
The first shock was felt over an area of 270,000 square kilometers. The second shock was a little weaker covering 180,000 square kilometers.
“Its impact was especially severe in the towns of Oia and Fira on Thera, Santorini. In Santorini almost all the buildings were damaged. Altogether 529 buildings were destroyed, and of those 326 were on Santorini” (2). Along with buildings being destroyed the Skaros rock/castle had been shaken repeatedly by earthquakes and the 1956 one is what destroyed it completely. Before and after images of the rock are shown (Figure 4, 5, and 6).
“This rock was inhabited during medieval times and offered protection from pirates. It is now totally uninhabited, since it’s so strongly fractured and can drop into the sea at any moment” (2).
I can see this rock from every angle when I look out onto the caldera. It has been an iconic scene to look at everyday. Now that I know the story behind it’s fractured presence I’m even more intrigued by it.
Other tragic events that happened from the earthquake included 53 people losing their lives between Santorini and the neighboring islands (2).
“In Oia the public water cistern was destroyed. Because of the lack of water the village of Agrilia on Therasia had to be evacuated as well” (2).
There is a lot to learn from tragic events that happen. What should be taken away from these types of events is to be prepared for the unexpected. An example of that could be having to sacrifice one thing for another depending on the situation that is giving to you. The children on the boat survived but their parents didn’t and I would like to think the parents helped save their children over themselves.
What this little but mighty island could keep in mind to better prepare for earthquakes like the 1956 one is to always build with reinforcing iron to make stronger structures. Also to avoid building on overhanging cliffs and major fault zones in the area.
Sources:
1) Bell et. al. Submarine evidence of a debris avalanche deposit on the eastern slope of Santorini volcano, Greece. Tectonphysics. 597-598, (2013), 147-160.
2) Friedrich, W. L. (2009). Santorini, Volcano, Natural Histroy, Mythology. 235-240.
The addition of the maps help strengthen this blog. I really enjoyed the intro…it captivated me to read more. I think it could have been strengthened by an explanation of why the earthquake occurred. In this case, the earthquake originated along the Anafi Fault Zone (and not from the subduction zone as some might expect). In your next post, try to strengthen your conclusion. A general rule to follow is to write one sentence that summarizes every paragraph in your post.
Thanks and well hopefully my last blog has a better conclusion
Hi Tayrena,
It was a great idea to begin the entry with an interesting background story about the location you were discussing in the rest of your post. It made me much more interested in the rest of your entry. Your two maps showing the epicenters of the earthquake and aftershock helped visualize the occurrence and magnitude of the earthquake when it happened. You set the stage for information and interesting facts very well. The information on Skaros Rock was also quite engaging. With that information you provided about the rocky structure I’ve learned both geological and Greek history in one blog. The pictures leave room for imagination of what it must have been like when it was first constructed.
Thank you for your thoughtful response!
I like this post, though aspects regarding the geologic causes of the activity would have been useful to frame. Have building codes been updated and enforced in the last 60 years? Figure 4 is really nice.
Thank you for your response, and I think they have been updated to iron with in the concrete for better structural support. At least that’s based on what I’ve seen around the island so far when they are building new structures.