This study investigates the Rocca di Mezzo area in the central Apennines (Italy) to evaluate the presence of a hypothesized active and capable normal fault underneath a school edifice. A multimethod approach was applied, including geologic field data, borehole data analysis, paleoseismological trenching, stratigraphic analysis. Field observations indicate the absence of structural features affecting the Meso‑Cenozoic bedrock associated to extensional faulting in the sector where the supposed fault should be located. Only structural evidence of reverse faulting related to an inactive compressive tectonic phase was found. Stratigraphic data also indicate that the Meso‑Cenozoic bedrock dips gradually westward, buried by Quaternary sediments in the area where the fault was hypothesized, so that the lateral contact between the bedrock and the Quaternary sediments is just related to the stratigraphic setting. Trench excavations across the southern sector of the suspected fault trace revealed lacustrine sequences, with interbedded paleosols, undisturbed by any fault planes. Radiocarbon and archaeological dating confirm the Holocene age of these lake deposits, consistent with other nearby lacustrine sequences, indicating that multiple sectors of the plateau hosted small lakes during the Holocene whose oscillations have been controlled by karstic‑related processes. This oscillation has determined phases of deposition and erosion that have strongly conditioned the evolution of this part of the plateau. The present‑day geomorphic characteristics of the area, including ponds and numerous dolines, suggest that karstic drainage and local erosion controlled the apparent deepening of the bedrock. The deepening is not therefore caused by the activity of the presumed fault, but it is just caused by local erosion led by karstic processes. These results demonstrate that indirect data or few hints of supposed fault activity can lead to misinterpretation of the presence of active faults. Misinterpretation can be solely ruled out by integrating multiple lines of geological evidence framed in a comprehensive neotectonic analysis, which allows resembling the whole geological evolution of an area over long time spans.

Ancient Pompeii is known worldwide for having been destroyed by the Plinian eruption of Vesuvius in 79 CE. However, the city experienced a prolonged period of seismicity preceding the catastrophe, beginning with a major earthquake in 62 CE, the effects of which are identifiable in the archaeological structures. This study examines multiple lines of evidence for superimposed, ancient seismic damage in four contexts excavated between 2018 and 2025, through an integrated multidisciplinary approach. The archaeoseismological investigation includes the stratigraphic analysis of elevations, the identification of construction techniques, building materials, and decorative styles, geoarchaeological stratigraphy, geotechnical aspects, and the characterization of the potential site effects through ambient vibration (Horizontal-to-Vertical Spectral Ratio) measurements. The results reveal building damage attributable to up to three seismic episodes (designated as early, intermediate and final) separated by phases of repair/reconstruction/reinforcement. A seismic episode may be represented by a single event or, alternatively, by multiple undistinguishable events, collectively designated as a damaging phase. The final episode is consistently associated with the seismicity accompanying the eruption. Volcanological evidence further indicates that syn-eruptive seismic shaking caused significant damage during the Plinian phase, consistent with the earthquakes reported by Pliny the Younger. Overall, the recurrence of seismic events, in addition to the 79 CE eruption, played a fundamental role in shaping the archaeological heritage preserved within the Pompeii Archaeological Park.

The active Mt. Morrone Fault (MMF) and the related Sulmona intermountain basin constitute one of the most characteristic examples of the extensional tectonic landscape carving the central Apennines (Italy). Above the ∼ 22 km MMF, thousands of inhabitants concentrate on a thriving reality and a historical and cultural heritage of great significance. According to current knowledge, the last activation event of the whole MMF occurred ∼ 2000 years ago, and the maximum expected magnitude is M 6.6–7.0. Thus, the MMF today constitutes one of the most problematic structures in the central Apennines seismotectonic setting in terms of large-magnitude earthquake probability. Despite this, information on the activity of the MMF is presently relatively sparse, both for associated historical seismicity and paleoseismological data. To strengthen these knowledge weaknesses, we performed new extensive paleoseismological analyses (employing four trenches) in the central sector of the fault. Our goal was to supplement the limited existing dataset, constituted by a single paleoseismological study close to the northwestern tip of the fault. Additionally, we aimed to incorporate findings from a pair of studies focused on archaeoseismological and speleoseismological secondary evidence. Through these analyses, we unveiled four significant surface rupture events of the MMF, three of which occurred over the past 6000 years BP. Specifically, the youngest identified event occurred after 3.6–3.5 kyr BP, thus being chronologically consistent with the event in the second century CE, a penultimate event after 4.4 kyr BP, a previous event that occurred after 5.4–5.3 kyr BP, and the oldest event that took place after 9–8.9 kyr and (presumably) before 5.8–5.7 kyr BP. Considering that the estimated cumulative minimum vertical displacement encompassing the last three events is ∼ 140 cm, and based on the length of the fault at the surface, we can confirm that earthquakes with M 6.6–7.0 may be expected from the activation of the MMF with an inferred average recurrence interval not longer than 1800 years over the last ∼ 5.4 kyr.

Surface faulting and liquefaction are two earthquake-related effects to be considered in geological hazard assessment studies, particularly in application cases involving the construction or reconstruction of strategic buildings. The first effect is connected to the coseismic rupture on surface occurring along the active and capable fault, whereas the second relates to the ground seismic shaking and occurs mostly on sandy-silty grain sized deposits with shallow water table. Here, the results of investigations carried out in the Pagliare di Sassa village, nearby L’Aquila (central Italy), are presented, with the aim of shedding light on a potentially active and capable fault previously hypothesized at a site selected for the building of a school. The acquisition of paleoseismological, geophysical and geognostic data allowed to rule out the presence of the active and capable fault in the school area and to characterize several soft sediment deformation structures, interpreted as seismites related to two earthquake-induced paleoliquefaction events. Their occurrence has been linked through ceramic and radiocarbon dating. The seismites were used to determine the likely historical earthquakes (date, seismogenic source and magnitude), which in turn helped determine their occurrence contributing to the comprehension of the seismotectonic setting of central Italy. Lastly, the assessment of these local seismic instabilities, evidenced by the case study of Pagliare di Sassa, represents a key prerequisite for best practices in land and urban planning, devoted to the building of strategic edifice, such as a school. In such cases, the application of palaeoseismological technique proves to be invaluable for mitigating the seismic risk.

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.

The ancient city of Pompeii, destroyed by the 79 CE Plinian eruption of Vesuvius, is one of the most famous archaeological sites worldwide and an open-air laboratory for many disciplines. The destruction of Pompeii has so far been reconstructed in terms of a succession of volcanic phenomena and related effects, identified as the accumulation of pumice lapilli on roofs and dynamic pressure exerted by pyroclastic currents on buildings, and neglecting the potential effects of the syn-eruptive seismicity, the occurrence of which is beautifully described by an erudite eyewitness to the catastrophe, Pliny the Younger. During a recent excavation in the Insula dei Casti Amanti, in the central part of Pompeii, the peculiar evidence of building collapses, that overwhelmed two individuals, has been uncovered. The multidisciplinary investigation, involving archaeology, volcanology, and anthropology, gathered information on the construction technique of the masonry structures, the volcanological stratigraphy, the traumatic pattern of bone fractures of the skeletons, along with the detection of the wall displacements, that led to archaeoseismological considerations. The merging of the data has highlighted the need of an updated perspective in the assessment of the damage at Pompeii during the 79 CE eruption, by considering the syn-eruptive seismicity as a factor contributing to the destruction of the city and death of the inhabitants. By comparing the attitude and characteristics of different types of damage, and after ruling out any other possible damaging event, our conclusions point to the occurrence of syn-eruptive earthquake-induced failures of masonry structures. The structural collapses, based on our stratigraphic and volcanological data, are chronologically consistent with the beginning of the caldera-forming phase of the eruption which was accompanied by strong seismic shocks. The crush injuries of the skeletons of the two individuals are consistent with severe compression traumas and analogous to those shown by individuals involved in modern earthquakes testifying that, apart from other volcanic phenomena, the effects of syn-eruptive seismicity may be relevant. These outcomes lay the foundation for a more extensive study concerning the assessment of the contribution of the syn-eruptive seismic destruction at Pompeii and open new perspectives for volcanological, archaeoseismological and paleopathological studies.

The occurrence of coseismic surface ruptures along fault traces in urbanised areas creates a serious hazard to the vulnerability of man-made manufactures. In order to mitigate such hazard, it is necessary to investigate the geometry, the activity and the capability of faults located close to urbanised areas. This paper presents a case study of the investigation of capable faults within a sensitive area in Italy that is characterized by a high density of population and industrial activities, high levels of seismicity and the presence of faults proven to be capable of rupturing the surface during medium-to-large earthquakes. We focused on the Luco fault (Fucino basin, Central Italy), which previous studies have suggested to cross the industrial district of the town of Avezzano. We present a multidisciplinary approach, consisting of Electrical Resistivity Tomography surveys, continuous-coring boreholes and paleoseismological trenches, aimed at accurately constraining the trace of the Luco fault and documenting the associated fault displacement. This allowed us to constrain the geometry of the Luco fault and to assess the associated fault displacement hazard. We suggest that the proposed methodology represents a pilot study for further investigations of capable faults in the Italian and other similar seismotectonic contexts.

Methods of Earth Sciences have been employed in archaeological sites of the Marsica region, central Italy, in two different perspectives: to enhance knowledge on past natural events which damaged/destroyed ancient settlements/monuments and to gather data useful/necessary for preservation of the local cultural heritage. Within this wide perspective, the paper deals with (i) recent archaeoseismological investigations at Alba Fucens and other sites of the Fucino Plain which add evidence of sudden building collapse to the already available (archaeoseismological and paleoseismological) data concerning seismicity of fifth-sixth century AD; (ii) archaeological investigations on remains of the Medieval church of San Bartolomeo showing that coseismic damage in 1349 caused the abandonment of part of the building and its (re)use for burials; (iii) evidence of slope instability which caused rapid mass deposition in the lowest sector of ancient Alba Fucens since around the half of the sixth century AD, inhibiting the occupation of the Roman town; (iv) capable faulting potentially affecting the westernmost sector of the huge hydraulic works made by Romans during the first-second century AD to drain former Lake Fucino.

Up to now, the complexity and the uncertainty in defining the extent down-dip and along-strike of active faults led to the elaboration of several methods to establish structure 3D geometry. Therefore, different approaches produce different scenarios of seismogenic rupture for the same active tectonic structure. Here we investigate two active fault systems of the central Apennines of Italy: the Roveto Valley Fault and the Laga Mts. Fault. We specifically aim to the understanding of along-strike segmentation of these tectonic structures to contribute to improve the knowledge of the seismotectonic setting of the central Apennines. Overall, our goal is to make a step forward toward the comprehension of the wide theme of seismogenic fault segmentation. The main uncertainties regarding the two fault systems are different. In the case of the Roveto Valley Fault, the uncertainty is twofold: 1) the current activity of the fault is debated; according to some authors, fault activity ended during the Middle Pleistocene, whereas others suggest the fault is still active and seismogenic; 2) the extent of the proposed active section of this tectonic structure is not clearly defined, and this is relevant in a seismotectonic perspective. The Laga Mts. fault system is a complex tectonic structure whose activity is well geologically documented for the southern section of the system; moreover, the fault system played a key role in the seismogenic process of the 2016-2017 central Italy earthquake sequence. Some authors interpret the fault as the surface expression of a single large seismogenic source, capable of generating seismic events of Mw ≈ 6.7. Other authors, instead, propose that this system consists in two structurally aligned but kinematically independent faults, the Amatrice and Campotosto faults. Following the 2016-2017 seismic sequence, an important debate is taking place within the scientific community about the definition of 1) the individual seismogenic sources that make up the Laga Mts. fault system and 2) the geometric and kinematic relationship between the fault(s) at surface and its (their) possible prolongation at depth as crustal major seismogenic sources. Through morphological, morphotectonic and structural analyses we propose segmentation criteria and possible segmentation scenarios for these two structures. These allow us to estimate the maximum coseismic rupture and the maximum magnitude expected from a single seismic event for the investigated fault, improving the seismotectonic knowledge of the central Apennines.

The Seismic Microzonation, as practiced in Italy, consists in defining microzones of the territory affected by homogeneous response to seismic ground shaking, defined as stable zones, vulnerable seismic amplification zones, and unstable zones. In detail, the unstable zones are affected by landslides, soil liquefaction, ground subsidence and surface faulting. In this framework, we conducted a study in the administrative district of L’Aquila (central Italy) aimed at the construction of a new school building, in an area indicated as prone to surface faulting (an active and capable fault was hypothesised in the area) and liquefaction. We dug two trenches (named as A and B) perpendicular to the presumed active fault trace. The excavation walls exposed several different continental units mainly characterized by colluvial, organic-rich and “cultural” sediments, as well as paleosols. In trench A, some units, made of sandy-gravelly colluvial deposits, contained abundant pottery fragments, being intensely reworked by very recent human activity. These units were mainly composed of silt and sand sparse with carbonate clasts and directly overlying Middle Pleistocene alluvial deposits. Trench B only exposed units containing pottery fragments and hence pertaining to historical times. Several radiocarbon dating made on charcoal found within these units confirmed the recent age of the deposits, spanning from 25000 to 1800 years before the present. The analysis of the trench walls, the analysis of two boreholes, and field geological investigations revealed the absence of any surface faulting events affecting the stratigraphic sequence of the area, at least since the Middle Pleistocene, likely since the Early Pleistocene. Furthermore, trench B exposed several sedimentary dikes reaching up close to the ground surface, crossing the historical colluvial units, as well as other deformation features typical of liquefaction phenomena. The radiocarbon age determination and the sedimentological characteristics of the units indicate that the most recent liquefaction event occurred after 180 A.D. Ultimately, this work represents a “best-practice” case study to investigate the occurrence of geological surface criticalities (such as surface faulting and liquefaction) at specific sites of interest.

We investigated the Late Quaternary activity of a major, crustal fault affecting the southern sector of Central Apennines, i.e., the Roveto Valley Fault (also known as Liri Valley fault). This sector of the chain was hit by numerous M>5 historical seismic events. For some of these, e.g., the 1654 one (M w 6.33), the causative seismogenic source has never been conclusively defined. Within this seismotectonic framework, the recent activity of the Roveto Valley Fault is still a matter of debate. Some authors defined its activity as ended in the Middle Pleistocene; others considered it as currently active and seismogenic at least in its southern portion. We collected new geologic and geomorphologic data along the eastern (left) flank of the Roveto Valley, where the fault crops out, and we identified evidence of displacement of alluvial fans that we attributed to the Early, Middle, and Late Pleistocene. Moreover, the analysis of the relationship between colluvial/detrital deposits, chronologically constrained by means of radiocarbon dating, allowed us to define the activation of the Roveto Valley fault also during historical times, that is, over the past few centuries. Evidence of this has been collected along a large sector of the fault trace for a length of some tens of kilometres. The results of our studies contribute to improve the knowledge of the seismotectonic setting of a large sector of the Central Apennines. Indeed, proving the current activity of the Roveto Valley fault casts new light on possible seismogenic sources of major seismicity of central Italy, potentially responsible for severe damage over a wide area and to relevant cities, Rome being among them.

Surface faulting is, together with strong ground shaking, a hazard associated with major earthquake faults. Assessing surface faulting potential of a given active tectonic structure is a fundamental prerequisite to adequately plan the use of territories and to perform new constructions, in order to act practices aimed to mitigate the associated risk. Assessing the surface faulting potential represents also ground for correctly performing re-construction and retrofitting of buildings and infrastructures during post-earthquake activities. We investigated a branch of a major seismogenic normal fault in the central Apennines of Italy, the Campi-Preci fault, along which the monumental Sant’Eutizio Abbey is located. The medieval Abbey is one of the most important cultural/religious edifices of the central Apennines, heavily damaged by the MW 6.5 October 30, 2016, earthquake, focused a few km to the south. Our study, based on field geological, geomorphological and structural survey and trenching investigations revealed that I) the trace of the Campi-Preci active fault branch is not actually located where presently reported in the available literature, II) the supposed morpho-tectonic features (basically, some km-long scarp carved on the Meso-Cenozoic carbonate bedrock), that suggested the presence of the fault segment in the area of the Sant’Eutizio Abbey, are not related to the active fault but are probably associated to a presently inactive reverse fault and III) the Sant’Eutizio Abbey is likely not potentially affected by primary surface faulting. Our work highlights that only a comprehensive multidisciplinary approach allows to correctly assess surface faulting potential in both seismotectonic and engineering perspectives.

The entanglement between active tectonics and karst systems is well-known in the literature. Karst systems are sound recorders of continental deformation in terms of brittle structures and seismic features and have been successfully used as markers for reconstructing tectonic stresses and assessing preferential directions of increased permeability in oil and gas fields. Karst systems could also be exploited to evaluate the past activity of faults bounding karst hydrostructures, thus providing useful data for the assessment of the seismic hazard of a specific area. In this work, we look into the complex relationship among karst development, recent tectonics and groundwater flow, which appear to be strongly interconnected with each other, to assess the activity of faults bounding karst hydrostructures. We focused our attention on an active karst area located in the Mesozoic and Cenozoic carbonate reliefs of the Italian central Apennines. In this context, the morphological and morphometric features of the karst landforms (dolines, dry valleys, and cave entrances), identified with geomorphological surveys, and their mutual relationship with fractures and fault segments, identified employing geostructural analysis, document stasis and deepening events in karst evolution. Such events are related to changes in the groundwater table and the consequent variation of the paleokarst base level associated with the Quaternary fault activity. A comprehensive evaluation of the evolution of karst systems at local and regional scales, considering the hydrogeological influence on base levels, allows us to use karst landforms as a proxy to unravel fault activity and evolution in Italy and in other similar karst environments.

The resettlement of villages strongly damaged by catastrophes during the 20th century played a key role in the modification of the Apennine landscape in Italy. Following their abandonment, the remains of the medieval settlements progressively deteriorated in their ruined condition, becoming ghost villages often made of sparse portions of buildings, traces of outer walls, and isolated vestiges of ancient monuments colonized by vegetation. Five cases of central Apennine abandoned villages in the Abruzzi region (Frattura, Sperone, Albe, Salle, and Gessopalena) were investigated, combining information on the local adverse geological conditions with the historical reconstruction of their abandonment and resettlement, based on archive documents from the 19th and 20th centuries. The history of these localities was conditioned by two strong earthquakes that struck the Abruzzi region in 1915 (magnitude 7.1) and 1933 (magnitude 5.9), and by slope instability. In all cases, abandonment and resettlement produced new villages against the background of ancient ruins and remains. In conclusion, the paper discusses the potential use of the material traces of local histories with educational aims. Geological evidence of natural hazards, remains of the abandoned settlements and resettled villages could be arranged in museums aimed at increasing the awareness of natural hazards and risks.

The Fucino lacustrine basin in central Italy is a large flat area mostly devoted to agriculture, with urbanization along the perimeter of the ancient lake. In 1915 a strong earthquake struck the area (Mw 7.0), producing large damages and geological effects, including surface faulting, ground failures and liquefaction. A channel excavated in the lacustrine sediments exposed ground failure, with dykes of fine-grained sediment that we interpret as the result of earthquake-induced liquefaction. We present the results of a multidisciplinary work aimed at characterizing in detail the geology of the buried stratigraphic succession, its susceptibility to liquefaction and the likely source of the fine-grained liquefied material. The succession down to 20 m deep is formed by fine-grained sediments younger than similar to 170-180 kyrs (mostly Late Pleistocene-Holocene), prevailingly silt or silt-clay mixtures. The geological field analysis indicates that the dykes are filled by prevailing silt, liquefied and transported by upward-directed flow of short duration, as for earthquake-induced liquefaction. Tilting and lateral spreading accompanied the process. The overall liquefaction potential derived from the "simplified methods" is high. Correlations of X-Ray Powder Diffraction mineralogy of samples from drilling cores with those from dykes allowed us to identify the most likely source layer filling dykes, corresponding to a silt layer at 7-8 m depths. This layer and the dykes lack illite and montmorillonite clay particles. These results contribute to improve studies of liquefactions in sediments that differ from typical liquefiable loose sands. They have also implications for microzonation studies. Most samples show grain-size curves that do not fit within the field of potentially liquefiable soils, suggesting that criteria based on grain-size can be poorly significant in seismic microzonation studies of recent (Late Pleistocene-Holocene) lacustrine, fine-grained successions.

The Quaternary Fucino basin in the central Apennines of Italy was struck by one of the strongest Italian earthquakes of the last millennium (1915, Mw 7.0). The Avezzano town, similar to 9.0 km away from the epicentre, was completely destroyed. In the surrounding area sizable coseismic surface deformation were catalogued, attesting the severity of earthquake, the proximity to the causative fault and the geological and geomorphological complexity of a basin filled by thick lacustrine sediments. The Avezzano area provides a case study to understand how shallow subsurface geology influences site effects in a deep Quaternary continental basin environment, thus being of potential interest for similar geologic contexts worldwide. Within the investigated area, different possible earthquake-induced effects can occur, such as a) stratigraphic amplifications in a wide range of resonance frequencies (from 0.4 to 15-20 Hz); b) liquefaction; c) coseismic surface faulting; d) basin-edge effects; and e) slope instability. We present and discuss results of basic seismic microzonation study (SM) of the Avezzano area, focusing on geologic constraints aimed at the reconstruction of the shallow subsurface geology, and associated potential for local seismic hazard. We adopted an interdisciplinary approach based on detailed geological-structural, geophysical and seismic analyses to investigate the seismic response of high-seismic risk area, such as the Avezzano town, given the urban and industrial expansion since the last century. We discuss methodological approaches and their uncertainties.

The term active and capable fault (ACF) defines an active tectonic structure able to rupture permanently the ground surface. When an ACF represents the expression at surface of a seismogenic source, the study of an ACF involves a twofold aspect: one concerns surface faulting hazard, with engineering implications regarding infrastructures crossing the trace of a ACF, the other concerns the definition of geometric and kinematic characteristics of seismogenic sources, with implications regarding the definition of the seismogenic potential of a given active tectonic structure. Here, we show the results of geological investigations regarding two case studies in the central Apennines. The first site is located near the village of Venere dei Marsi (AQ), where the detailed characterization of geometry and kinematics of a fault splay connected to "San Benedetto dei Marsi - Gioia dei Marsi" active fault segment, allowed us to verify the effectiveness of the ACF territory zonation proposed in "Guidelines for the management of territories affected by Active and Capable Faults" promulgated by the Dipartimento della Protezione Civile Nazionale of Italy in 2015. The second case study is located close to Preci (PG), where field geological investigations were aimed to verify the presence of an ACF in the area of the Sant'Eutizio Abbey severely damaged by the 30 October 2016 Mw 6.5 seismic event, for retrofitting activities, and to characterize the Campi fault segment in terms of recent activity. This allowed to better define the geometric and kinematic characteristics of seismogenic source, responsible for the 2 February 1703 (Mw = 6.8), nucleated by the Norcia active faults system.

We investigated the eastern corner of northeastern Italy, where a system of NW–SE-trending dextral strike-slip faults of western Slovenia intersects the south-verging fold and thrust belt of the eastern Southern Alps. The area suffered the largest earthquakes of the region, among which are the 1511 (Mw 6.3) event and the two major shocks of the 1976 seismic sequence, with Mw = 6.4 and 6.1. The Colle Villano thrust and the Borgo Faris–Cividale strike-slip fault have been here first analyzed by interpreting industrial seismic lines and then by performing morphotectonic and paleoseismological analyses. These different datasets indicate that the two structures define an active, coherent transpressive fault system that was activated twice in the past two millennia, with the last event occurring around the 15th–17th century. The chronological information and the location of the investigated fault system suggest its activation during the 1511 earthquake.