GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.1 GNGTS 2023 It is interesting to point out that, unlike the path undertaken in these years by seismology, the collection of data by Scarabelli and Tassinari on the Imola earthquake appears extraneous to meteorological observations. In fact, a few years later the Barnabite Francesco Denza founded the Moncalieri Meteorological Observatory (1859), which will be the first of an extensive network of meteorological observatories that also served to record seismic activity (not only that detected by the first instruments), whose results were published in the “ Corrispondenza meteorologica italiana delle Alpi e degli Appennini”. Also in those years the Vesuvian Observatory was born for meteorological and physical research. The widespread network of seismic observatories that has grown in the wake of meteorology would be of little use without a conceptual tool that could somehow measure and compare events. At this point are relevant the activities of Michele S. De Rossi. He deserves credit for having drawn up and published a seismic scale in 1874, as well as having organized a dense network of correspondents since 1873, whose observations were collected and published in the “ Bullettino del vulcanismo italiano ”, founded and financed by De Rossi himself. This network was made up of gentlemen naturalists, with a passion for observing phenomena and often equipped with measuring instruments installed inside the house (Molin et al., 2008; Tertulliani, 2019). Unfortunately, the disastrous earthquakes in Casamicciola (1881, 1883) and in Liguria (1887) spurred the way for a national seismic service, and at the name of the Royal Central Meteorological Office, located in the historic headquarters of the Roman College, was added “and of Geodynamics”. At this point, the social composition of the observers changed. From the noblemen who sent cards with a manuscript concise account of instrumental or observable effects of the quake, it moved on to public observers, not necessarily particularly trained technicians. It is estimated that in 1888 the network headed by the national seismic service had 492 observation points, most of them in telegraph offices (170), port authorities (155), thermo-pluviometric stations (117), private (35), agricultural schools (8) and meteorological observatories (7) (Ferrari, 1990). At the same time, the way of collecting information changes and the story of “macroseismic postcards” begins. Note that for a single earthquake there are as many postcards as there are places from which the corresponding report was sent. When we are faced with macroseismic postcards, we can observe two or three different “levels”, which can be analyzed separately, although they are closely intertwined with each other. The first level is the printed text, the form to fill out. The second is the text compiled by the local observer. The third is not often present in the postcards but it is almost always found during the 1930s: they are the annotations - usually in pencil - by some member of the Seismic Service’s staff. It should be remembered that from 1889 postcards containing a pre-printed form that standardized and directed the observer's operation began to be used. The first postcards contained both instrument and macroseismic information. The first main concern of the printed text was the need to specify the time of the earthquake as much as