Earthquakes, fingerprint discovered

Thanks to satellites, the fingerprint of earthquakes is discovered and the areas with the greatest seismic intensity of an earthquake can also be recognized from the analysis of the images. Through the images obtained from satellite interferometry, a team of researchers from the Sapienza University of Rome and the National Institute of Geophysics and Volcanology (Ingv) analyzed the “fingerprint” of earthquakes through the recognition of the soil deformation that accompanies a seismic event. Scientists, in fact, have been able to accurately estimate the size and recognize the area where the most violent shaking accompanying earthquakes are concentrated. The study “The epicentral fingerprint of earthquakes marks the coseismically activated crustal volume” has just been published in ‘Earth Science Reviews’. The images obtained with the InSar technique (Interferometric Synthetic Aperture Radar) allow to detect the cosismic deformation – that is, the instantaneous and permanent deformation caused by the earthquake – delimiting the epicentral area where the greatest displacement is concentrated, through the analysis of the deformation of the ground around the fault activated during an earthquake. “In the research we analyzed 32 seismic events, with the aim of comparing the deformation fields in terms of shape, spatial extension and volumes of the earth’s crust involved both by the mobilization and by the simultaneous crossing by seismic waves, and the corresponding type and earthquake magnitude “explains Carlo Doglioni, president of Ingv and Professor of Sapienza. Doglioni reports that “the size of the deformed earth surface area detected by InSar for earthquakes with a magnitude of 6 or greater is always greater than 100 km2, while it is also over 550 km2 for earthquakes with a magnitude of about 6.5. Furthermore, the comparison between InSar and peak ground accelerations documents increased shaking within areas that experience greater vertical deformation. ” “Since 1993, a long list of seismic events has been analyzed with InSar data, ever increasing thanks to the increase in the number of satellites, the improvement of the quality of Sar sensors, and InSar techniques in continental areas” underlines Patrizio Petricca, researcher della Sapienza, and Christian Bignami of Eng. “With them – the researchers add – it is possible to detect the cosismic deformation, delimiting the epicentral area where the greatest displacement is concentrated. Outside this area, apart from local amplification phenomena, the displacement of the soil decreases, determining the attenuation of the seismic shaking “. “The knowledge of these earth manifestations – finally assures Doglioni – helps to focus more specifically the seismic prevention in the future epicentral areas, helping to calibrate the evaluation of the seismic hazard in which the vertical movement plays a relevant role in increasing a greater horizontal shaking. and therefore greater damage. Why earthquakes will return: on average in Italy about 20 destructive earthquakes are generated per century “.