A group of scientists headed by Greek professor Ioannis Baziotis have used a modern geochemical technique to draw conclusions on how tectonic slabs melt underneath the Santorini volcano, causing eruptions.
The international team applied the pioneering geochemical method of research in the rocks of Santorini.
“The purpose of this study,” as Professor Baziotis told the Athens – Macedonian News Agency, “was to bring together two great, yet different, disciplines of geology science, petrology and geochemistry. Through the study of stone chemistry we were able to answer questions that concern the field of geophysics and seismology.”
Greece, a highly seismogenic country, owes its high seismicity mainly to the convergence of two tectonic plates, namely the subduction of the African tectonic slab under the Eurasian equivalent.
“It is extremely important that there was an agreement between the estimated conditions calculated from the petrological-geochemical models of the new work, with the existing geophysical data already generated by local seismic recordings,” Baziotis said.
The most recent major eruption of the Santorini volcano occurred in the 16th or 17th century BC. According to the professor: “The concern of scientists has always been the decipherment of the ‘heart’ of the volcano of Santorini, this heart which, like in the human body, feeds all the vital organs with blood.
“In the case of the volcano, it feeds with magma the surface of the earth. But where is the magmatic chamber of Santorini in which magma is stored? And what procedures predate the magma concentration in the chamber?”
Scientists took samples from the volcanic rocks on the surface of Santorini and analyzed them with a number of techniques regarding their basic minerals and geochemistry (main elements and trace elements). Then, using – for the first time in Greece – a special geochemical model developed by the Japanese professor Jun-Ichi Kimura, they proceeded to simulate the behavior of the main elements and the trace elements.
Using the method, scientists estimated that the tectonic plate of Africa releases fluids from a depth of about 145 km. This depth is the same as the one resulting from the study of seismic data (intermediate depth earthquakes), thus outlining the upper surface of the underlying tectonic slab of Africa under the Eurasian one.
Thereafter, the fluids released from the depth of 145 km follow an almost vertical course upwards, reaching a depth of approximately 56-69 km. This depth, resulting from the geochemical models, is in harmony with the seismicity observed at 70 km (the lower limit of the deep earthquakes) and is attributed to the lithosphere-oscilloscope boundary.
According to the study, from the depth of 56-69 km, the Earth’s mantle melts, creating melts concentrated in a temporary magmatic chamber. Sometimes they begin to climb to a lesser depth and concentrate in the magma chamber beneath the volcano of Santorini, which is at an estimated depth of 0.7 kilometers, before they eventually reach the surface during a volcanic eruption.
Professor Baziotis stressed that “with our study, using petrological and geochemical data, we contribute to a deeper understanding of the operation of the submerged zone in the Greek space.
“In addition, the methodology followed may be applied more generally to any equivalent subsoil and convergence zone of Earth’s tectonic plates, with the ultimate goal of an in-depth understanding of the structure of a submersion system.”