GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 in the completeness of the listed localites' seismic histories. This operaton could allow to systematze a considerable amount of data that so far has remained under-used or even unused. We called "superstudy" this approach of integratng, in a single dataset, data derived from several diferent studies of the same event. However, to carry out this task is not a straightorward procedure, and some critcal issues exist, mainly due to the inhomogeneity of the diferent intensity dataset. This inhomogeneity is due to diferent methods of collectng informaton and assigning intensity, adopted by diferent research groups, in diferent "historical" periods, also sometmes using diferent intensity scales or diferent kinds of geolocalizaton (e.g. municipal area or hamlets). The purpose of this work is to understand whether it is possible to integrate such diferent datasets into a coherent whole, quickly and efciently (I.e. without performing a deep revision of each event), without lessening the quality of the resultng intensity assignments. To check this, we made an experiment that started with the selecton of a number of earthquakes, occurred in the period from 1985 to 2006, for which several diferent studies are available. The selected earthquakes are provided with studies of diferent kinds, from reports of macroseismic feld surveys, to questonnaire data collectons and to preliminary reviews. Fig.1 – Example of the superstudy of the September 9, 2003 earthquake. From the lef to the right, CPTI15 preferred study (Bernardini et al., 2003) 134 Mdps, the other available source (BMING11, Gasparini et al., 2011) 613 MDPs and the fnal superstudy, MDPs 693 MDPs. Integratng macroseismic studies of diferent nature does not simply mean combining intensity values as they are. On the contrary, it requires frst to individuate some homogenizaton criteria that allow to optmize the quality and quantty of informaton. As mentoned above, dissimilarites in macroseismic data mostly result from the diferent practces of data collecton followed at diferent tmes, according to the methodologies used, and from the kinds of intensity scale used and how they were used. The studies associated with the selected earthquakes provide data sets that difer both in the number of points and in the assessed intensity values. In some cases we fnd that a given locality is included in all studies, with coincident intensites or sometmes with diferent intensites. It can also happen that several MDPs are present in one only of the studies of the same earthquake. To bring our appointed task to completon both efciently and systematcally, it is necessary to establish some criteria and accept some approximatons about the nature of data, as for example, considering MCS and EMS intensites <5 to be equivalent. This project, at the moment, involves more than 40 earthquakes with a total of about 4,000 MDPs, which will increase to around 10,000