You Sea, I Sea, We All Sea Tsunamis

When first entering this course, I had no clue what to expect. When Lisa told me my hazard was Tsunami, I thought to myself “we are here to study volcanoes, why the heck do I have to know anything about tsunamis?” Little did I know that this class was a whole lot more than just volcanoes. Tsunamis form at tectonic plate boundaries; however, there affects can span out in every direction and cause destruction wherever they hit. For us students currently staying in the Aegean Sea, a tsunami could be extremely deadly for us if one were to hit while we were here. Tsunamis may be cool, but if you see one coming you better get running somewhere high before it hits.

The Aegean Sea touches Europe, Africa and The Middle East. The two tectonic plates that sit beneath the Aegean Sea are the African Plate and the Eurasian Plate, these plates meet and create a subduction zone that in this map is highlighted in red as the Hellenic Trench.

A subduction zone is an area where two plates meet and begin to press into each other. The thinner oceanic crust slides, or subducts, under the thicker continental crust. The two plates you see labeled in this diagram are the plates that could cause the tsunamis we would potentially experience here in Santorini.

Tsunamis form at subduction zones due to the stress of subduction that strains the rock. Once the strain reaches a point where it can no longer be help the rock experiences an elastic rebound to its original shape. This causes a large amount of water to displace, creating the tsunami swell that is sent out in all directions.

In the deep ocean, tsunami waves are not as noticeable. As the tsunami approaches land it begins to swell. The wave cannot do its normal cycle when reaching shallow water so instead of continuing as normal it turns into a more oblique shape. It pulls water from in front of it, retreating it from the shore, and then it begins to build upwards.

Once the tsunami reaches land, it will run up onto the land into any area that is low enough in elevation that its wave height can reach. On Santorini, there are cities that are at sea level as well as cities that are higher up on the caldera rim. Any area in the red zone, or run up zone, is likely to experience the affects of run up from the tsunami. In this case, it would be smart for the people of this city to hike up onto this mountain the same way we did the other day to escape the flow of water.

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