GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.1 GNGTS 2023 It is quite clear that a system based on the propensity and capability of local administrators had not been sufficient to cover the national territory in a homogeneous and effective way. Furthermore, once the mayors were no longer elected by their own citizens, but were chosen directly by the central government, it is probable that they were conditioned, like the periodical press, towards a manly reduction and resizing of the entity of the problems or of the critical moments that could arise: in this case earthquakes. Not even the journalistic correspondence collected by the Seismic Service could be sufficient to cover the seismic activity that was taking place in the Italian territory, considering that most of the news clippings found among the postcards of the 1930s came only from the Roman newspaper La Tribuna . These are some of the difficulties that the Seismic Service found in gathering information. Of a different nature are the problems posed when interpreting the data received. At this point we can consider the third “layer” of the postcards, the traces left by the staff of the Seismic Service. Perhaps the main problem that they found in evaluating the contents of the postcards was the extreme synthesis of the answers. Among the diagnostics indicated in the postcards, in the answers there were a couple, sometimes only one: "the quake woke up a large number of people" or “It's been felt by quite a few people”. It is a problem when the description of the effects and the intensity value assigned by the same local observer do not coincide and must be corrected by the Seismic Service. Worse is the case when the postcards have only the indication of the degree in the macroseismic scale, without the possibility by the Seismic Service to verify the data. During the Thirties, there are at the top of the postcards an inscription in pencil, in which the staff in Rome indicates the estimated intensity. This may or may not coincide with the one indicated by the local observer, but almost always coincides with the one published in the supplement “ Macrosismi ” of the Bollettino Sismico . It should be noted that sometimes an uncertainty sign (“?”) accompanies the intensity value (Fig. 2).