Over 11,700 earthquakes occurred in Santorini and nearby area between January 26 and February 7, an analysis by the Interdisciplinary Committee for Risk and Crisis Management of the National University of Athens (EKPA), published on Sunday, February 9, 2025. has shown.
At the same time, a small and gradual decrease in the number of earthquakes in the Cyclades islands has been observed in the last two days, while experts’ estimates on the evolution of the phenomenon differ.
According to what was announced, based on the daily analysis of seismic data (without the use of machine learning methods) of the Seismology Laboratory of the National University of Athens, on February 8, 95 earthquakes were recorded, of which 13 with magnitudes M≥4.0 and 3 with M≥4.5, while the largest earthquake had a magnitude M=4.8.
What the EKPA analysis shows
Since the start of the earthquake swarm in the Santorini-Amorgos zone on January 26th until February 7th, 2025, the Laboratory has detected and located a total of over 11,700 selected earthquakes with machine learning (artificial intelligence) methods, of which over 9,600 with magnitudes of M³1.0.
On February 6th, over 1,400 earthquakes were recorded, with ~400 having a magnitude of M³2.5, 18 earthquakes with M³4.0, and 5 earthquakes with M³4.5, with the largest earthquake having a magnitude of 4.7.
On February 7, over 1,300 earthquakes were recorded, with ~270 having a magnitude of M³2.5, 8 earthquakes with M³4.0, and 2 earthquakes with M³4.5, with the largest earthquake having a magnitude of M=4.8.
Below: Map of earthquakes in Cyclades (Santorini-Amorgos-Ios) recorded 6-7 February and 8th February.
Most of the earthquakes are located in a section ~12 km southwest of Anydros, which was already active in the previous days.
Despite the intensity of the earthquakes, a slight decrease has been observed in the last two days.
NKUA monitors the area in real time through a special page that offers an interactive map with seismic data and active faults.
The COLUMBO research program
Meanwhile, an international research team has been studying the activity of the submarine volcano Columbo, one of the most active submarine volcanoes in the Mediterranean, 7 km. northeast of Santorini, through the SANTORY research project.
The international SANTORY team includes scientists with many years of experience in the study of the Greek volcanic arc from the Department of Geology and Geo-environment and the Department of Physics of the National Kapodistrian University of Athens, the Institute of Marine Biology, Biotechnology and Aquaculture of the Hellenic Center for Marine Research, the Remote Sensing Laboratory of the National Technical University of Athens, the National Institute of Geophysics and Volcanology of Palermo, the University of Milan-Bicocca and the Spanish company Ploatech, coordinated by the professor of Geological Oceanography of the National University of Athens, Paraskevi Nomiko.
The research program, which is funded by the Hellenic Foundation for Research and Innovation (ELIDEK), according to a relevant update from the EKPA, has yielded significant scientific results, strengthening the knowledge available about the underwater volcano Columbo.
“With the recent seismic tremors in the sea area of Santorini, everyone’s attention is focused on the underwater volcano Columbo. Columbo, although invisible from the surface 7 km northeast of Santorini, is one of the most active underwater volcanoes in the Mediterranean. Its last eruption in 1650 caused the emission of toxic gases that cost the lives of over 70 residents of Santorini, while the tsunami that followed caused serious material damage to Santorini, Ios and Sikinos,” the announcement stated.
The Columbo volcano is a unique natural laboratory for SANTORY scientists, which they have been studying for twenty years. “The aim of our research team in the SANTORY program is to continuously monitor its activity with state-of-the-art instruments in order to assess how active its hydrothermal field is and to analyze how dangerous it is for the population of nearby islands,” the announcement notes.
In detail, special sensors have been placed inside the crater at a depth of 500 meters that measure physicochemical parameters (temperature, pH, gas concentrations, pressure, etc.), inclinometers to measure sea currents inside the crater and special thermometers to measure changes in the temperature of its chimneys. In addition, optical cameras have been placed in front of active vents to record the hydrothermal flow of fluids, as well as a special camera to record the texture of the seabed and a UV CHERI camera to detect Cherenkov radiation, something that is being done for the first time on a global scale. Finally, they have installed instruments for real-time gamma-ray measurements.
“As part of our research, water samples were taken inside the crater for microbiological analyses with the aim of identifying super-resistant bacteria. Gases and hydrothermal fluids were also collected from the very active chimneys,” the research team emphasizes and adds: “Through these efforts, we have for the first time a time series of data for two time periods from the Columbus crater, that is, not individual measurements but a pattern that reveals the daily life of the volcano. These data are valuable, as if we know its typical activity, any changes in the physical-chemical and acoustic parameters will show us changes in its active behavior.”
According to the relevant information from the National University of Athens, innovative results emerged from the programs, highlighting the uniqueness of the underwater volcano Columbo, including:
1. Recording changes in physical and geochemical parameters: These changes are associated with the volcanic activity of the active hydrothermal field of Columbo and its volcanic hazard was assessed.
2. Recording extremely high natural radiation: For the first time, data were recorded showing very high levels of natural radiation within the hydrothermal field of Columbo.
3. Isolation of microorganisms from the extreme environment of Columbo: These microorganisms are of particular interest for their utilization in areas of biotechnology, as they have unique mechanisms for adapting to extreme conditions.
4. Metagenomic analyses: These analyses revealed new information about the carbon and methane cycles, which directly affect our planet’s climate.
Continuous monitoring of Columbus is essential for assessing volcanic hazard, as is applied internationally in the surveillance of submarine volcanoes.
