An innovative approach has made it possible to highlight the proportion expected in the future between the number of mild and strong seismic events in two macro-areas of the Italian territory
Determine the relationship between the quantity of small and large earthquakes observed in the past and, therefore, expected in the future in our country (scientifically “b-value”) was the object of the study just published by researchers atNational Institute of Geophysics and Volcanology (INGV) in the Nature journal 'Communications of Earth and Environment'.
The Gutenberg-Richter law underlying the determination of this work establishes that the number of earthquakes observed decreases as the magnitude increases: in other words, a much greater number of small earthquakes than large ones.
The INGV researchers who conducted the study used geodetic data and a statistical approach to understand, starting from the measurement of very small deformations of the Earth's surface, the intensity of the tectonic forces that govern our Planet and the reaction that these generate on the earth's crust.
“Satellite geodesy is a fundamental tool for us as it allows us to establish whether, over the decades, the distance between two points on the earth's surface in areas subject to seismic events is increasing or decreasing”, explains Michele Carafa, researcher at INGV and co-author of the study. “Depending on the case, in fact, we can expect compressional earthquakes in the future, if the distance between points on the earth's surface is decreasing, or extensional ones, if the distance is instead increasing”.
Since the b-value is not spatially uniform but can vary depending on the geographical area of reference, the INGV study analyzed the extension and compression zones of our country in parallel, with the aim of obtaining more information on the number of strong earthquakes expected in the two areas.
“The b-values that emerged from our work are actually different for the two areas (the areas in extension have a higher b-value than those in compression), but much closer to each other than one might have thought”, he adds Matteo Taroni, researcher at INGV and co-author of the study. “This means that the behavior of earthquake magnitudes in geologically different areas is actually quite similar”.
Statistical calculations then confirmed how the geodetic approach with the division of the national territory into just two analysis areas gave more effective results compared to previous subdivisions into smaller areas, paving the way for possible future collaborations between the world of geodetic modeling and that of statistical seismology.
“Since the b-value is one of the fundamental parameters used to estimate the seismic hazard of a territory, we hope that other works will confirm the results of our study, so that this new approach can be used to improve the Italian seismic hazard model, that is, the document at the basis of all seismic risk mitigation and prevention actions in our country", they conclude Taroni e Carafe.
Determine the relationship between the quantity of small and large earthquakes observed in the past and, therefore, expected in the future in our country (scientifically “b-value”) was the object of the study just published by researchers atNational Institute of Geophysics and Volcanology (INGV) in the Nature journal 'Communications of Earth and Environment'.
The Gutenberg-Richter law underlying the determination of this work establishes that the number of earthquakes observed decreases as the magnitude increases: in other words, a much greater number of small earthquakes than large ones.
The INGV researchers who conducted the study used geodetic data and a statistical approach to understand, starting from the measurement of very small deformations of the Earth's surface, the intensity of the tectonic forces that govern our Planet and the reaction that these generate on the earth's crust.
“Satellite geodesy is a fundamental tool for us as it allows us to establish whether, over the decades, the distance between two points on the earth's surface in areas subject to seismic events is increasing or decreasing”, explains Michele Carafa, researcher at INGV and co-author of the study. “Depending on the case, in fact, we can expect compressional earthquakes in the future, if the distance between points on the earth's surface is decreasing, or extensional ones, if the distance is instead increasing”.
Since the b-value is not spatially uniform but can vary depending on the geographical area of reference, the INGV study analyzed the extension and compression zones of our country in parallel, with the aim of obtaining more information on the number of strong earthquakes expected in the two areas.
“The b-values that emerged from our work are actually different for the two areas (the areas in extension have a higher b-value than those in compression), but much closer to each other than one might have thought”, he adds Matteo Taroni, researcher at INGV and co-author of the study. “This means that the behavior of earthquake magnitudes in geologically different areas is actually quite similar”.
Statistical calculations then confirmed how the geodetic approach with the division of the national territory into just two analysis areas gave more effective results compared to previous subdivisions into smaller areas, paving the way for possible future collaborations between the world of geodetic modeling and that of statistical seismology.
“Since the b-value is one of the fundamental parameters used to estimate the seismic hazard of a territory, we hope that other works will confirm the results of our study, so that this new approach can be used to improve the Italian seismic hazard model, that is, the document at the basis of all seismic risk mitigation and prevention actions in our country", they conclude Taroni e Carafe.
Figure: The black curves enclose the compression zones (left) and extension zones (right) of the Italian peninsula; the color scale indicates the horizontal strain rate.