Today, the Greek island is a tourist paradise thanks to its historical and natural wonders, but few people know that there is an active undersea volcano in its immediate vicinity. The volcano called Kolumbo is just a few kilometers northeast of Santorini, and in September 1650 it had a violent underwater explosion. produced an eruption, during which a volcano that had just reached the surface of the sea collapsed, sending pyroclastics of hot gas and debris hurtling towards Santorini, where 70 people (and many hundreds of cattle) died. As a result of the eruption, a tsunami was generated with a wave height of 3-20 meters, which destroyed a distance of 150 km. Although this eruption cannot be compared to the ancient, history-shaping eruption of Thera, it begs the question: what would happen if such an eruption took place today in the tourist-filled Aegean Sea?
Sketch of the 1650 eruption of Columbo.
Source: Scientific Reports
In the undersea caldera of Kolumbo, as revealed by an investigation carried out a few years ago, there are hundreds of hot water vents from which gas-filled water of more than 220 degrees Celsius flows continuously, this heat also indicates that under Kolumbo even today magma can be found (a submersible survey found a weak small hydrothermal spring in the underwater caldera of Santorini).
The region is part of a volcanic arc connected to a subducting plate margin, and as such, it can provide dangerous surprises and large, explosive eruptions. In a recent, Geochemistry, Geophysics, Geosystems in a research published in a specialized journal, they measured what lies beneath the Columbo by means of a special version of seismic tomography.
The most commonly used method of seismic tomography is to measure the path of standard vibrations created using compressed air “cannons” mounted on a ship. With this method, the hidden secrets of the subsurface rock layers can be explored, whether it is a hydrocarbon treasure or the magma reservoir of volcanoes.
Source: Wikimedia commons
Seismic tomography is somewhat similar to medical ultrasound examinations: with the help of the propagation of earthquakes and vibrations, the deep area is mapped, including if there is at least partially molten magma under a volcano. In this way, for example, the magma reservoir under the volcano can be identified, and the rate at which it receives fresh supplies can be assessed – thus helping to predict a future eruption to a great extent.
Geological features of the Aegean Sea, from the subducting African plate margin to the active volcanic island arc (top, in green).
Source: Wikimedia Commons
In the case of Kolumbo, it was possible to identify the magma reservoir, and they were able to calculate the rate at which it was able to fill, which means that currently approx. 1.4 cubic kilometers of magma has accumulated in it since its eruption in 1650. If it continues to charge at the current rate, then approx. In 150 years, it can reach the 2 cubic kilometer amount of melt that left in the eruption at that time. Of course, this does not mean that we can sunbathe on the beaches of the surrounding islands for another 150 years, but rather that it is time to carry out continuous measurements on the underwater volcano as soon as possible, so that any changes can be noticed immediately by the experts. If Kolumbo were to erupt, it would be of a similar nature, albeit on a significantly smaller scale, than the one in Tonga a year ago, so it would be very important to monitor it in such a frequented region. Fortunately, they have already started building it an underwater volcanic observatorywhich will monitor the events of both Santorini and Columbus.
