No matter how small or hidden, off the beaten path or disregarded due to a seemingly greater phenomenon, everything has a secret. The Santorini caldera may be dominantly significant enough to most our area of study, however, it is only one of the many volcanic sites that make up the Santorini Volcanic Field in the Aegean Sea.
What has recently caught my interest has been the submarine volcano named Kolumbo. It has been built up from under the sea just 8 km north east of Thira and is part of the Santorini Volcanic Field. The crater is 1.5 km wide, 505 meters deep in the centre and has a south west rim only 10 meters in depth. There was not much of a will nor way for mankind to explore the depths of the Mediterranean Sea 365 years ago, and so the first time volcano revealed its underwater hiding spot was in 1650 AD after its sub-plinian eruption. The eruption caused pyroclastic surges that flew across the sea. Pyroclastic surges are explosions that are created when water turns to gas as it comes in contact with magma, causing it to shoot laterally out of the vent. The Kolumbo surges reached the north east shores of Thira on Santorini killing 70 people. Erosion has kept the volcano under the waves ever since.
The studies of earthquakes near Kolumbo has lead scientists to believe that magma has been moving around under ground trying to seep through the cracks of the Kolumbo fault . The Kolumbo fault is one of the two main faults in Santorini. It cuts through north east Thira and stretches up to the Kolumbo volcano. From our day at sea touring the inter cliffs of the Santorini caldera, I took a picture of where the fault line cuts through Thira (fig.3)
Very little had been known about the volcano since its debut until 2006 when a group of oceanographers from University of Rhode Island collaborated with the Hellenic Centre for Marine Research in Greece to investigate the Minoan eruption deposits near and on Kolumbo. When they sent their remotely operated vehicle (ROV) down in the Kolumbo crater, they discovered much more than ash deposited. Reddish-orange bacteria started to appear. This bacteria that was found 300 meters deep in the Kolumbo crater reminds me of the bacteria from the hydrothermal hot springs that we all swam in on the west shore of Nea Kameni (fig.4). The crater, being so deep and sheltered by the ring of the rim, has created a sustainable environment for these bacteria to grow in mass quantities without getting disturbed by Mediterranean Sea currents.
The researchers later discovered that the reddish-orange bacteria were thriving off hundreds of hydrothermal vents scattered along the north interior of the crater. Most of the vents were chimney and seeps. A chimney is the structural product of hot intense hydrothermal gas flow, where as, a seep is much less intense in heat and pressure which created a less significant structural complex. Some chimneys, having accumulated minerals since the 1650 eruption, have reached up to 4 meters in height. One of the researchers from University of Rhode Island explains, “Most of the known vents around the world have been found on the mid-ocean ridges in very deep water and in areas where there are geologic plate separations,”… “The Koloumbo and Santorini volcanoes are in shallow water at plate convergences, the only place besides Japan where high-temperature vents have been found in these conditions” . The crater, being so deep, acts as a nest for the microorganisms to flourish in their construction process. Samples of the structures were analyzed and found to have a lot of metals mixed with an array of minerals. The vents had been a mystery us humans until the 2006 expedition. In the comments, I will post a link to the 2006 expedition summary which gives great basic Information of the discovery.
The exploration to the Kolumbo volcano lead to the discovery of these magnificent submarine structures. After the 2006 expedition, the neglected underwater volcano reached headline news. The underdog of the Santorini volcanic field revealed its secret of unique topography and hydrothermal structures. Yes, the Santorini caldera is a famous volcano and it is what brought our group over seas, however, like in my first blog post, “Santorini isn’t Alone”, there is much more to be recognized about the volcanism of the Aegean Sea.
 NOAA, Sigurdsson, Haraldur, 2010, Thera 2006 Expedition Summary, http://oceanexplorer.noaa.gov/explorations/06blacksea/logs/summary_thera/summary_thera.html (June 2015)
 Santonet.gr, 2015, Exploration of the Submarine Crater of the Kolumbo Volcano, http://www.santonet.gr/santorinivolcano/eruption_newevidence.htm, (June 2015)
 D. Sakellariou, H. Sigurdsson, M. Alexandri, May 2010, The Kolumbo Submarine Volcanic Zone, Bulletin of the Geologic Society of Greece, N2, pg 1056-1057