Earthquakes, Italy’s seismic Tac completed

It is being disseminated by the National Institute of Geophysics and Volcanology

earthquakes, created the ‘Tac’ of the Italian peninsula, a seismic tomography of Italy which reveals new details on the deep structure and geodynamic evolution of the Alps and the Apennines, It is being disseminated by the National Institute of Geophysics and Volcanology which provided a homogeneous representation of the three-dimensional structure of the entire Italian region up to a depth of 80 km, so as to improve the understanding of the birth and evolution of the Alpine and Apennine mountain ranges. The results of the study “Lithosphere Structure, Processes, and Physical State of the Alpine-Apennine System” were recently published in the “Journal of Geophysical Research”.

Through the use of Seismic Tomography, a technique similar to Computerized Axial Tomography (Tac) which is used in the medical field, it was possible to determine how the seismic waves P (compressional waves) and S (transversal waves) propagate below the Italian peninsula, identifying the ‘fast’ zones, i.e. associated with dense and cold rocks, and the ‘slow’ ones, composed from less dense and ‘warmer’ rocks. Through the analysis of the P and S waves generated by an earthquake, seismic tomography therefore makes it possible to obtain three-dimensional images of the interior of the Earth, just as the medical CAT scan allows the reconstruction of the inside of the human body through the use of X-rays .

“The formation of mountain ranges is the result of the collision between the tectonic plates into which the lithosphere is divided, i.e. the most superficial, cold and rigid part of our planet”, explains Pasquale De Gori, a researcher at Ingv. “The spatial, lateral and in-depth definition of the limits of these structures, whose reciprocal movement gave birth to the current structure of the Italian peninsula, is therefore fundamental for defining its geodynamic evolution” he adds. The tectonic plates are in perennial and slow motion and the collision process to which they are subject determines the sinking of large portions of volumes of the lithosphere inside the earth’s mantle (subduction). “The phenomenon of subduction causes important variations in the chemical and physical state of rock volumes which respond differently to elastic stresses”, continues Pio Lucente, also a researcher at Ingv. “One way – he explains – to study these heterogeneities is to calculate how the speed of propagation of the seismic waves which pass through them varies following the genesis of an earthquake”.