In this work the results of historical-macroseismic studies concerning the 1930 events are shown. Due to the availability of new sources (from archives and newspapers) and a renewed methodological approach, which it has led to a new interpretation of the known documents, the data regarding events already included in CPTI15 have been updated and expanded. Many new events have been added enriching the available data, both quantitatively and qualitatively. The quantitative aspect concerns the number of events as well as the increased number of macroseismic data (Mdp). The qualitative aspect concerns the description of the earthquake effects for most of the Mdp. Furthermore, other events have been included that for various reasons contribute to the seismic characterization of the Italian peninsula and others, finally, that have not been recorded by the contemporary seismic service and should not be lost. The data set is in the appendix and is collected in eighty cards corresponding to 118 events.
The Parametric Catalogue of Italian Earthquakes CPTI15 v 4.0 [Rovida et al., 2022] does still include 226 earthquakes whose epicentral parameters are based on preliminary studies carried out in the first half of the 1990s and identified by the acronym AMGNDT95 [Archivio Macrosismico GNDT, 1995]. These studies are 'preliminary' in the sense that generally they limited themselves to analyse the bibliographic references of the PFG catalogue [Postpischl, 1985a] - i.e. in the case of pre-1900 earthquakes mostly the Baratta [1901] compilation-and to derive epicentral parameters from these references or, at best, from the sources they quoted (when available), that is, usually, other seismological compilations or local historiography. For some years now, an operation has been underway to update AMGNDT95 studies and improving their quality as far as possible. Many of the results of this operation have been published in the INGV series "Quaderni di Geofisica", under the collective title "Materiali per un catalogo dei terremoti italiani" (Materials for a catalogue of Italian earthquakes), a title inspired to a work by Baratta [1897]. Some of these initiatives concerned particular areas of North-Eastern Italy, such as the Treviso area [Baranello, 2023; Baranello et al., 2024] and the Carnia-Friulian Preals area, which is the subject of the present work, aimed at reviewing and updating knowledge on a group of strong earthquakes of the 1700s and carried out within the framework of the PRIN 2020 project Caputo et al. (eds) [2025].
In 1904, professor Francesco Cavani, commissioned by the Municipality of Bologna, was tasked with evaluating the stability of the Garisenda Tower. To this end, he developed an innovative monitoring system, based on a plumb line fixed about 40 meters high on the south wall and specialized telescopes, equipped with a double system of lenses and focuses, capable of detecting displacements with precision up to one- twentieth of a millimeter. The tables attached to his report present in detail the monitoring data, including time series of the eastward and northward displacements, represented at a 20:1 enlarged scale. In this study, the original series were digitized, scaled, and exported for analysis using modern methods. The goal is to extract information on the dynamic characteristics of the tower's motion, both in the time domain and in the frequencydomain. The results highlight the oscillations and their corresponding amplitudes, providing a modern and updated interpretation of the dynamic behavior of the structure over a century later. This work aims to disseminate basic information on the tower's behavior in the past, to assess potential significant changes in the kinematic characterization of its movements in future studies. Additionally, future developments are announced to enhance the understanding of the spatial and temporal limits of the results, considering the imperfections of the historical graphs.
For almost twenty years, the Italian community of historical seismologists has been developing a wide and articulated research programme for updating and improving the macroseismic database used by compilers of the national earthquake catalogue to calculate increasingly accurate and reliable epicentral parameters. The initiatives carried out include: indepth studies of single earthquakes, detailed reconstructions of the 'seismic histories'of single localities/areas, and large scale study campaigns. These aimed at i) conducting preliminary (or 'expeditious') studies for historical earthquakes above the damage threshold that currently lack them, ii) updating or improving outdated or preliminary data, and iii) identifying and studying as many earthquakes as possible that exceeded the damage threshold but still 'unknown' to historical seismology and hence to the national seismic catalogue. The present work gathers the results of research on eight earthquakes located in the present Provinces of Treviso and Belluno between 1709 and 1949. Seven of these are included in the current version of the CPTI15 catalogue based on preliminary reference studies. The eighth and most recent one, instead, falls into the category of 'neglected' earthquakes, that is, those that were mistakenly excluded from the parametric reference catalogue in the 1980s [Postpischl, 1985] and that, to date, remain absent from the current version of the parametric catalogue. The work is in continuity with a previous study of 'minor' seismicity in the Asolo area and, together with it, makes a significant contribution to advancing the knowledge of the historical seismicity of the Veneto and Friuli Pre Alps.
The earthquake occurred in the NWsectorof the Marsica region (AbruzziApennines, central Italy) on 24 February 1904 has been parametrized in the modern Italian seismic catalogues with magnitude Me 5.6 (CFTI5Med [B1: Guidoboni et al., 2018]) and Mw 5.68 (CPTI15 [B1: Rovida et al., 2022]). This event damaged a region which, differently from the adjacent LA'quila sector of the Apennines, was not characterized by a significant seismic history. The scientific and popular view of a territory seismically negligible was still further contradicted eleven years later, on 13 January 1915, when the same area was struck by a catastrophic event (Mw 7.08 [B1: Rovida et al., 2022]), responsible for new damage (in some cases complete destruction) of the settlements already damaged in (and repaired after) 1904. Later on, the geological investigations since the 1970s showed that the above mentioned earthquakes had occurred in a sector of the Apennines affected by recent and current fault activity [B1: Bosi, 1975; Bertini e Bosi, 1976; Giraudi, 1986; 1988; Serva et al., 1986; Galadini e Messina, 1994; Michetti et al., 1996; Galadini e Galli, 1999; Cavinato etal., 2002; Galli et al., 2012; Gori et al., 2017a; Patruno e Scisciani, 2021]. Some of the cited works deal with the 30-Km-long fault emerging along the western and northern borders of the Fucino basin, considered as the causative source of the 1915 earthquake (Figure 1). In short, the modern geological and geomorphological knowledge indicates that the occurrence of strong seismic events would not be unexpected in this part of the central Apennines. The characteristics of the 1904 earthquake summarized in the above-mentioned parametric catalogues are based on a study published in the 1990s (i.e., the catalogue CFTI1 fB1: Boschi et al., 1995]), giving a distribution of the intensities according to the MCS macroseismic scale. Intensity data from that analysis indicate that the mainshock caused significant damage to several villages (Rosciolo dei Marsi, I 9 MCS; Magliano de' Marsi, I 8-9 MCS; Cappelle, Gallo, Poggio Filippo, San Donato, SantA'natolia, I 8 MCS). This estimation was mainly based on reports of the effects published at the beginning of the 20(th) century fB1: Monti, 1906; Cavasino, 1914], the critical reading of some newspapers of that time and of the telegrams sent from authorities of the damaged region to the Ministry of the Interior. However, information published at the beginning of the 20(th) century was not based on surveys made by seismologists or geologists and the recent and current research has not uncovered technical reports by scientists among the sparse documents regarding the 1904 seismic event. The first estimations on the earthquake effects benefited of short communications sent by people living in the region struck by the shocks (sometimes mayors of the damaged small towns) to Ufficio Centrale di Meteorologia e Geodinamica at Rome and of the descriptions of the effects by special correspondents of newspapers. A picture of almost complete destruction can be derived from many journalistic passages, due to the literary emphasis used by newsagents to describe the consequences of the earthquake. These newspaper views were almost uncritically included in the old scientific publications above mentioned, favoring the estimation with high MCS intensity values also in the modern contributions which considered the old literature to quantify the earthquake effects. These aspects made a new study of the 1904 earthquake necessary, and the opportunity was given by recent considerations, discussions and activities on the 120(th) anniversary of the seismic event, commemorated in two of the villages damaged at that time (Rosciolo dei Marsi and Scurcola Marsicana). Our investigation was based on: i) the critical review of the available literature, especially of the contributions published more than one century ago; ii) the reading of a greater number of newspapers compared to those used in previous studies (i.e., 18 newspapers for the period February-July 1904 and 4 newspapers for the period February 1904-January 1905); iii) the analysis of historical documents from archives at Rome and in the Abruzzi region (Archivio di Stato dell'Aquila, Archivio Storico Diocesano dei Marsi atAvezzano, Archivio Storico del Comune di Magliano de'Marsi, Archivio Centrale dello Stato at Rome, Archivio Macrosismico dell'Istituto Nazionale di Geofisica e Vulcanologia at Rome). The already available and the uncovered documentary materials permitted to interpret some journalistic views as excessive and, therefore, to consider estimations in the old publications as not fully reliable. Presently, we believe that intensities (EMS-98 and MCS scales) should be attributed to the most damaged localities as follows: Rosciolo dei Marsi, I 8 EMS and MCS; Magliano de' Marsi, I 7.5 EMS and MCS; Cappelle, Gallo, Poggio Filippo, San Donato, SantA'natolia, I 7 EMS and MCS; Scanzano I 6.5 EMS and MCS; Scurcola Marsicana, I 6 EMS and 6.5 MCS; Marano, Massa dA'lbe,I6 EMS and MCS (Table 1; Figure 10). The intensities reported in Table 1 defined new parameters summarizing the characteristics of the earthquake, I-o 7.5, I-x 8, Mw 5.18 (Table 2), significantly lower than those available in the catalogues mentioned above. The collected information also permitted to define a list of aftershocks made of 77 events (Table 3), occurred between 25 February and 31 December 1904. Though representing a partial view of the whole seismic sequence, this new list defines a significant increase of the number of aftershocks (59) already reported in the publication by Molin et al. fB1: 1999]. Fourteen minor events (six of which were already included in the above-mentioned catalogue CPTI15, basing on the previous study by Molin et al. fB1: 1999]) have been considered as strong enough to have been responsible for further damage (i.e., I-x >= 5 EMS-98), as indicated by the studied journalistic sources or by archive documents. We refer to the shocks occurred on: 25 February (00:29), 26 February (00:45), 28 February (00:30), 1 March (01:52), 3 March (18:55), 10 March (04:21), 11 March (13:25), 15 March (01:15), 20 March (05:50; 07:50), 29 March (08:30), 6 April (19:25), 7 April (19:00), 13 April (05:57). The Intensity datapoints of the strong aftershock occurred on 25 February (Mw 4.4) are plotted in Figure 11. As for the seismogenic aspects, the 1904 earthquake has been attributed to the northernmost section of the Fucino fault, corresponding to that defined as Magnola Mts.-Mt. Velino fault (Figure 15) [B1: Galadini et al., 1998; Valentini et al., 2019]. This attribution was based on the consistency of the intensity datapoints distribution with the attitude of the fault. This purely geometric relationship has not changed after the revision of the earthquake, since net of the different intensity values, the geometry of the distribution is comparable to that available until now. However, the attempt to link the 1904 earthquake to the mentioned fault must consider the decrease of the magnitude proposed in our study. The association of a moderate magnitude earthquake to a specific fault potentially responsible for M 7 seismic events is not without pitfalls. Considering the less significant area of the seismogenic rupture, we cannot exclude that the studied earthquake was originated by a secondary fault not emerging at surface. Another aspect discussed in this study is represented by the repairs following the 1904 earthquake. This concerns the vulnerability of the buildings at Rosciolo dei Marsi, i.e., the most damaged village (I 8 EMS-98 and MCS). After the seismic event, many iron tie rods (and some buttresses) were placed on buildings damaged by the shocks of the seismic sequence and affected by precarious stability conditions (Figure 12). Contemporary eyewitnesses considered (and current residents still consider) these interventions as the main reason fora damage in 1915 significantly lower than that observed in the nearby villages. Paradoxically, the highest damage in 1904 was the reason for the necessary repairs at Rosciolo which decreased the vulnerability of the buildings and contributed to mitigate the impact of the 1915 earthquake. Still today, Rosciolo maintains original buildings of the past centuries with interesting, though partly abandoned, architectural emergences. By contrast, less widespread distribution of repairs, or no intervention at all, characterized other less damaged villages, with the consequence that buildings with very high vulnerability faced the test of the strong 1915 shaking with a catastrophic outcome.
