The study of the major earthquakes and the analysis of their tectonic meaning are very important elements in the assessment of the seismic potential, the seismic hazard and the area hazard.
The analysis of the seismograms of the historical earthquakes plays an important role in understanding the means of deformation energy release, the characteristics of propagation of the seismic waves and their interaction with the inhabited areas, in the area characterised by these events.
Until a few years ago, this kind of study was especially complex and there was a scarcity of practical results owing to the great difficulty in finding the historical seismograms, obtaining quality copies and getting all the information needed to interpret the recordings (instrumental constants, time corrections, etc.).
Today the seismograms recovered, catalogues and scanned at high resolution and in a qualitatively homogenous way and their related vectorialisation, all operations carried out at the SISMOS laboratories, have paced the way to a new and fundamental phase in this kind of study, making possible scientific objectives until now deemed impossible or hard to achieve, above all for the earthquakes of the early decades of the 20th century.
The aim of the SISMOS research activity is to extrapolate as much information as possible contained in the instrumental historical data in order to better study the important earthquakes of the 20th century, with particular reference to those prior to the advent of the WWSSN.
The main parameters of the events are studied: localisation, magnitude (Ms and Mw) and the focal mechanism, besides also paying particular attention to the estimate of the size of the fracture, compatibly with the quality of the historical recordings available. This approach allows us to integrate and improve the knowledge of the seismogenesis of the areas considered, above all where the contemporary seismicity alone does not allows us to highlight tectonically active structures, and to study the style of deformation and the properties of seismic release of the study areas. This sector of SISMOS is inserted into important national and international projects.