A Period of Unrest? About What?

“Is it safe for me to live on this island? Do I have time to sell my house?” Irini, a local worker in a shop of handmade goods, inquired to me and a classmate of mine after we told her our purpose for being on this island for three weeks. We assured her that she was fine for a long while, but there is no denying that Santorini is an island of unrest. Volcanic unrest, that is. There is so much volcanic activity within the caldera that there was a period of crisis that occurred between for fourteen months from the years 2011 to 2012. Here is the interesting part: a majority of inhabitants on Santorini don’t even know why this period was considered a crisis.

Between January 2011 February 2012, Santorini was experiencing what geologists called the 2011-2012 Crisis, or “Period of Unrest.” This crisis involved what many geologists identified as volcanic activity, and the rates of activity were alarming. The types of volcanic activity identified during this crisis was overactive thermal activity, ground floor inflation, land deformation, increased sea temperature, and seismic activity.

A graph depicting the increased number of volcanic-related events between 2011 and 2012.
A graph depicting the increased number of volcanic-related events between 2011 and 2012.

The excessive thermal activity was caused by Nea Kameni, the newest and still-active volcano of Santorini, emitting unusual amounts of volcanic gases from its fumaroles, which are vents in a volcano that solely evacuate gases from the magma as a result from the overactive hydrothermal activity. The fumaroles are degassing magmatic or hydrothermal gases that are being boiled, and are released from the ground. The kinds of volcanic gases that were emitted from the fumaroles were carbon dioxide, hydrogen, hydrogen fluoride, hydrogen chloride, and other gases that originated from deep within the magma chamber (1).

Another sign of volcanic activity observed was ground inflation, in which the crust above the magma chamber is expanding vertically due to the pushing of magma and volcanic rock. Just north of Nea Kameni on the ocean floor (which my classmates and I got the opportunity to pass over on our private boat tour of the inner caldera rim), the ground inflation at its highest point was 150 millimeters, which is accompanied by ground deformation.
To know more information about the ground inflation near Nea Kameni from the 2011-2012 Crisis, please visit Samantha Snyder’s most recent blog post, “Speaking with the Sea Floor.”

An additional characteristic of volcanic activity from the “Period of Unrest” was an increased temperature of sea water near Nea Kameni. According to Georges Vougioukalakis, “There have…been changes in the compositions and circulation patterns of fluids within the Kameni edifice. Fluctuations of sea temperature around the Kameni islands since September 2010 are attributed to increased discharge of hot fluids into the sea” (1).
This means that an increase in the secretion of hot volcanic fluids from Nea Kameni are getting mixed into the ocean water surrounding it, thus increasing the water temperature.

The seismic activity that was taking place on Santorini was probably the most notable volcanic activity that was recorded throughout the crisis.
Along the Kameni and Kolumbos Fault lines that cut through Santorini in a NE-SW striking direction and within and around the magma chamber, there were around fifty earthquakes a day of magnitude 3.5 or lower. These continuous tremors that occurred multiple times a day are called seismic swarms. These seismic swarms were caused by magmatic activity that took place under the Kameni islands (1). This magmatic activity is also the same reason for the ground inflation, in which the magma and volcanic rock in the magma chamber was being pushed against the crust, cracking the rock surrounding it and creating volcanic tremors.

Pinpoints of where volcanic tremors had been occurring under the Kameni islands during the 2011-2012 Crisis.
Pinpoints of where volcanic tremors had been occurring under the Kameni islands during the 2011-2012 Crisis.

Even though Santorini inhabits so many incredible geologic treasures–like gazing upon the ruins of Ancient Akroteri, hiking up the active Nea Kameni, and being surrounded by the Ancient Minoan eruption layers (all of which our class partook in)–many of the locals do not even know where all of these came from, or why they are here. The same goes for when the 2011-2012 Crisis occurred; when all of the volcanic activity was taking place, most Santorini locals had, and still don’t have, any idea what that crisis meant. What they also do not know is what could potentially happen in the short-term from when this time of unrest happened.

One of the possible, and most dangerous, short-term events that could result from the 2011-2012 Crisis could be a sub-Plinian eruption (1). The sub-Plinian eruption would generate small eruption columns that could range from a few meters to a few kilometers high. The eruption column would eject volcanic material, such as ballistic projectiles and ash and gases (1). The ash fall would generate severe respiratory problems, and the ash and ballistic projectiles would also cause cancellations in flights that would go to and from Santorini.

Also, additional seismic activity could take place, which could lead to weak caldera cliff stability (1). This cliff stability could cause the caldera walls to collapse, which would proceed to landslides and mass wasting. For more information on landslides and mass wasting from the 2011-2012 Crisis, please refer to Jonathan Mills’s most recent blog, “Life on the Edge of a Caldera Rim.”

A landslides on Skaros.
A landslide on Skaros.

A final hazard that could possibly take place from the 2011-2012 Crisis would be tsunamis (1). If more seismic activity happens, as a result, there would be a potential for tsunamis to be formed, especially if the earthquakes take place under the Kameni islands, which would be within the ocean floor, or if a large landslide falls into the ocean, displacing large amounts of seawater on the way.

Based on what occurred during the “Period of Unrest” and what could potentially happen to Santorini in the far future, it should be considered extremely crucial for Santorinians to know what is happening on the island geologically, and what the island is “trying to say” to them, which is that it is still alive and kicking. As an island that relies on tourism, the inhabitants should know how Nea Kameni would affect its tourism. It wouldn’t necessarily destroy Santorini, but it would bring life and the tourism industry to a halt. Maybe the Santorinians should read our class blog to know what the deal is…

Vougioukalakis, Georges, 2014, “Santorini Volcano Hazard Assessment: The 2011-2012 volcanic unrest,” (PowerPoint Presentation).

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One thought on “A Period of Unrest? About What?”

  1. I’m so proud of this blog! You once again did an excellent job of summarizing a large amount of material in terms that most non-geologists can understand. Your thoughts are well organized, and I have a clear idea of the potential hazards and results of this period of unrest. Wonderful job! I see another teaching lesson in the future??

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