The 1956 Amorgos Earthquake: The Day Santorini Literally Fell Apart

On July, 1956 the largest magnitude earthquake in Europe took place. It had a magnitude of 7.7 on the moment magnitude scale, and a maximum intensity of 9 (IX) on the mercalli intensity scale (1). The epicenter (The point on the earth’s surface where an earthquake originates from) was located to the south of the island of Amorgos, which is the easternmost island of the Cyclades in the Aegean Sea.

The 1956 Earthquake was the largest earthquake in Greece in the 20th century, and has not been matched since. The Earthquake left the island of Santorini completely devastated, and left the neighboring island of Amorgos with significant damage as well.

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Figure 1. This figure shows the 2 epicenters from the 1956 earthquake. The Island’s of Santorini, Eos, and Amorgos are also shown.

In Figure 1 the 1st epicenter (purple point) is the main shock and it had a surface magintude of 7.7. 13 mins later it was followed by an aftershock (blue point) earthquake with a magnitude of 7.2 (1). As you can see both epicenters were a good distance away from the island of Santorini, but it was the island that suffered the most damage. The first shock covered an area of 270,000 km and the second shock covered an area of 180,00 km.

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Figure 2. The direction of the Tsunami as it approaches the Island of Santorini from the east.

The Earthquake also triggered a tsunami. The tsunami affected most of the Aegean Sea. Because of the distribution of observed run ups, combined with the inconsistent timings of the wave arrivals at different locations, it was concluded that the tsunami was actually triggered by multiple underwater landslides due to the earthquake (1). The tsunami, with a maximum wave height of 30 m at the south coast of Amorgos caused damages within a region of 100 km. Amorgos is exactly 92.6 km away from Santorini (1). In Figure 2, you can see that the tsunami appproached Santorini from the east. A family of 7 was out on a boat that day when the wave hit Santorini, and completely capsizing the boat, killing both the parents (1).

The topography of Santorini plays a specific role in why the earthquake was able to cause so much damage. The cliff walls and soft sediment from the pumice and ash amplifies seismic waves at the surface.

The damage was severe, especially in Santorini. Oia was one of the cities mostly damaged by the earthquake, and that was because Oia was built on unconsolidated, fragmented pieces of scoria. The earthquake caused the stutters built on the scoria to fail and collapse. The earthquake completely demolished 529 houses and left many other houses damaged as well. 53 people were killed as a result of the earthquake, and two other people were killed as a result of the tsunami (1).

Many people were left homeless and traumatized because of the 1956 earthquake. The cost of repairing the buildings that were damaged were to great and so many people lot there homes and businesses. Thousands of people left the island of Santorini due to the earthquake.

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Figure 3. Oia, June 6th, 2018.

It has been 62 years since the 1956 Amorgos Eartquake that changed the lives of many Santorinians. The Earthquake left many of the buildings in ruins, especially Oia. But as you can see in Figure 3, Oia has not changed much. Most of Oia’s structures are built in exactly the same hazardess places that were completely demolished in the earthquake 62 years ago. If another earthquake of the same magnitude as the 1956 earthquake occurs, Oia would fall under the same devastating  events. Many of the building would collapse and some will even be subjected to major landslides. Santorini is a catastrophe waiting to happen.

Source:

1. “1956 Amorgos Earthquake” Wikipedia. Wikimedia Foundation, 08 June 2018. Web 27 December 2017.

4 thoughts on “The 1956 Amorgos Earthquake: The Day Santorini Literally Fell Apart

  1. Hi Tib,

    Gosh, everyone’s second posts have a level of disheartening facts. An earthquake at 7.7, followed 13 minutes later by an aftershock of 7.2, then a tsunami! I am familiar with earthquakes in North America and hadn’t heard of this earthquake. I like that you used the Greek for the name-place. You may as well since you’re living there and not solely learning from a book. I learned a lot from your post.

    What’s scoria?
    For future posts, you don’t need to take too much time away from your narrative to define or explain terminology. You can, for instance, provide a brief definition or analogy following the term in (parentheses) or with commas. “…Oia was built on unconsolidated, fragmented pieces of scoria (a X-material made of … therefore it crumbles).

    Then, the rest of us not only learn about but we can imagine what happens to scoria during an earthquake.

    These kinds of rhetorical skills in writing are often remembered best with Greek yogurt, cheese, and grilled items:
    https://www.tripadvisor.com/Restaurant_Review-g482941-d7068573-Reviews-Grill_House-Oia_Santorini_Cyclades_South_Aegean.html

    I look forward to your next post.

  2. Tib,

    This was an informative post about the 1956 earthquake and potential for more in the future that many tourist and even locals are unaware; however, I didn’t get to hear your voice in the post. I would challenge you to put your voice and experiences in your next post. An interest to you may be on boat day where you will have the opportunity to see the Church of the Seven Children, the church where the children on the boat got caught in the tsunamis and seeked refuge.

  3. For your next post be sure to include your thoughts, experiences, and impressions from the island. The blogs are a wonderful way to convey to readers, friends, and family about what you have both learned and experienced.

    There are some grammatical errors and spelling errors throughout (for example ‘earthquakes’ isn’t capitalized). For the third post, make sure to get a thorough edit from one or more students to check for those things.

  4. Saludos Tib!

    You did a good job of writing an entry for someone who might not know too much about this subject. The images you included help solidify information and your writing was straight to the point.

    Like the comments above were saying, don’t hesitate to have your voice seep into your posts. They can be informational, to the point, but also have another layer in order to keep your audiences interested. For example, isn’t it interesting that even after the 1956 earthquake, Oia was rebuilt in the same fashion? You and your class are studying these natural phenomena, but should the information you find through research such as this be used to rebuild cities or should we as humans know about the volcanos just for the sake of knowledge? Does this research justify investing money into infrastructure if it will save lives in the future?

    Don’t be afraid to ask questions in these posts even if they don’t have one solid answer! Otherwise, this was an interesting post and I look forward to your next one!
    -Nikki

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