Nappi, Rosa

More than forty years after the 23 November 1980 earthquake, which devastated the Campania and Basilicata regions, causing the destruction of a large number of towns and the death of around three thousand people, we have tried, through a large survey, to understand how and to what extent the urban fabric and the most affected communities have been rebuilt. Our main objective was to show, on one side, the commitment of the scientific community, and on the other the transitions that have led from the emergency to reconstruction. Of the Apenninic towns Conza della Campania, Laviano, Lioni, Santomenna, and others, where the devastation was almost total, we have tried to give an iconographic vision of the post-earthquake phase through the change in the urban layout. The partial or total reconstruction of the towns has taken place most of the time in situ, only in some cases by relocating buildings to neighboring areas, as happened in Conza della Campania, Bisaccia and Romagnano al Monte. Reconstruction was carried out mainly of anti-seismic buildings and only in some cases recovering preexisting buildings in historic centres; reconstruction was completed after a very long period, in some cases lasting over thirty years, inevitably passing through a dramatic experience of the population in temporary settlements of various kinds, from tents, caravans, railway carriages, to containers, and finally to thermo-igloos and to prefabricated wooden chalet-type. A very complex and detailed reconstruction was linked to factors not only territorial, economic and political but also conditioned unfortunately by the non-negligible intervention of organized crime.

Over the past two decades, the airborne Light Detection and Ranging (LiDAR) system has become a useful tool for acquiring high-resolution topographic data, especially in active tectonics studies. Analyzing Digital Terrain Models (DTMs) from LiDAR exposes morpho-structural elements, aiding in the understanding of fault zones, among other applications. Despite its effectiveness, challenges persist in regions with rapid deformation, dense vegetation, and human impact. We propose an adapted workflow transitioning from the conventional airborne LiDAR system to the usage of drone-based LiDAR technology for higher-resolution data acquisition. Additionally, drones offer a more cost-effective solution, both in an initial investment and ongoing operational expenses. Our goal is to demonstrate how drone-based LiDAR enhances the identification of active deformation features, particularly for earthquake-induced surface faulting. To evaluate the potential of our technique, we conducted a drone-based LiDAR survey in the Casamicciola Terme area, north of Ischia Island, Italy, known for the occurrence of destructive shallow earthquakes, including the 2017 Md = 4 event. We assessed the quality of our acquired DTM by comparing it with existing elevation datasets for the same area. We discuss the advantages and limitations of each DTM product in relation to our results, particularly when applied to fault mapping. By analyzing derivative DTM products, we identified the fault scarps within the Casamicciola Holocene Graben (CHG) and mapped its structural geometry in detail. The analysis of both linear and areal geomorphic features allowed us to identify the primary factors influencing the current morphological arrangement of the CHG area. Our detailed map depicts a nested graben formed by two main structures (the Maio and Sentinella faults) and minor internal faults (the Purgatorio and Nizzola faults). High-resolution DEMs acquired by drone-based LiDAR facilitated detailed studies of the geomorphology and fault activity. A similar approach can be applied in regions where the evidence of high slip-rate faults is difficult to identify due to vegetation cover and inaccessibility.

Lahars, landslides and debris flows are rapid natural phenomena that can heavily impact on and modify the environment, not only that from which they are triggered but also the one in which they propagate or leave deposits. In particular, lahars can reach significant runout distances from source areas (e.g., several km) and this can mainly depend, among other factors, on the morphology experienced by such propagation. There are cases in the recent history of natural occurrences in which lahars impacted catastrophically on rural and urban settings, such as for example at Nevado del Ruiz volcano (Colombia) in 1985 causing the death of thousands of people living around there. A more recent event occurred on November 26, 2022 at Ischia island (Italy), which is an active volcano particularly subjected to the recurrence of these phenomena. In this case, the emplacement of some lahars caused the death of a few tens of people and the damaging of tens of building, besides the direct impact on local agriculture and tourism. In the nearby Neapolitan volcanic area, several other lahar events occurred in the historical past, not only during but also after or well after explosive eruptions, as the evidence that these phenomena are still to be considered as complex and often unpredictable extreme natural events, also exacerbated by the climate changes, but also that they have some recurrence that cannot be neglected. Such kind of recurrence is mainly related to the local weather, which can even affect the intrinsic behavior of the flows that detach from the source areas and invade the territory. On the other hand, this is not a strictly statistical issue, as there are instrumental measurements that support the fact that heavy rains can exacerbate a landscape already prone to sliding, avalanching, and other catastrophic phenomena. For this, the November 26, 2022 Ischia case study was chosen with the goal of reconstructing the physical features that led to the lahar generation and invasion, which is something that might occur in the future but that should be experienced with a dedicated scientific and territorial consciousness. What was done is an integration of multidisciplinary approaches, corroborated by data from the INGV-OV monitoring network installed on the volcano, capable of detecting the otherwise lost flow timing and dynamical behavior. In particular, the seismic evidence that accompanied the Ischia lahar events, along with the consideration of some lithological features leading to an estimation of flow velocity and dynamic pressure, allow to discriminate multiple lahar pulses over the early morning of November 26, 2022. The main findings of this contribution are that the potential of the Ischia lahars had a sort of recharge timespan which depended on the local weather and lithological features, while the threshold of the lahar trigger depended on the hydrogeological conditions. The seismic reconstruction of the entire event allowed to quantify the first of these two critical issues at Ischia island.

This reprint "The November 23rd, 1980 Irpinia-Lucania, Southern Italy Earthquake: Insights and Reviews 40 Years Later” presents a collection of 13 scientific contributions proposed by 44 researchers with different expertise and multidisciplinary approach highlighting the most important aspects of the Irpinia-Lucania earthquake (Ms 6.9, Io X MCS) from a seismological and geological point of view, without neglecting the reconstruction of cultural heritage, the resilience of the population, and the socioeconomic development of the internal areas of the Southern Apennines after the earthquake. The 1980 earthquake struck Irpinia-Lucania region (Southern Italy) and it is remembered in Italy not only for being the strongest earthquake recorded in the last 100 years causing devastation of entire regions and severe loss of human life, but also for the destruction of the cultural heritage in the epicentral area. This volume, far from being exhaustive, nevertheless wants to be an important point of reference for the new generations of researchers who will have both a historical and multidisciplinary approach to the knowledge of this earthquake.

Evaluating and predicting the occurrence and spatial remarks of climate and rainfall-related destructive hazards is a big challenge. Periodically, Sinai Peninsula is suffering from natural risks that enthuse researchers to provide the area more attention and scientific investigation. Extracted information from the morpho-metric indices aids in understanding the flood potentiality over various sizes of drainage catchments. In this work, the morpho-metric analysis has been used in order to model the relative signals of flood vulnerability of 16 catchments in northern Sinai. The geospatial technique has been applied to process the digital elevation models (DEMs) in order to produce different analysis maps. Basic geometries, in addition to several morpho-metric indices, were extracted and analyzed by investigating the digital elevation models. Three different effective methods were applied separately to build up three models of flood susceptibility behaviors. Finally, two flood susceptibility signals were defined: the integration method and accurate pixel level conditions models. The integrated method analysis indicates that the western half of the study landscape, including catchments (12, 13, and 14), presents high levels of flood susceptibility in addition to catchment 9 in the eastern half, whereas the other catchments were found to provide moderate levels. The integrated flood susceptibility final map overlaid one of the most effective topographic indices (topographic position index, TPI). The integrated results aided in understanding the link of the general catchments morphometry to the in situ topography for mapping the different flood susceptibility locations over the entire study landscape. Therefore, this can be used for investigating the surface-specific reduction strategy against the impacts of flood hazards in the proposed landscape.

In this work several change detection techniques based on satellite SAR data acquired by Cosmo-SkyMed Second Generation missions have been evaluated aiming at detecting the landslide-mudflow phenomenon triggered by the strong flooding event that hit Ischia Island in November 2022. It severely impacted on Casamicciola Terme area causing damages and collapses of many buildings and unfortunately also casualties. Experimental results show how both Single- (SP) and Dual- (DP) Polarimetric techniques are able to detect the main landslide occurring along the northern flank of Mt. Epomeo and in some cases also connected phenomena such as mud accumulation. Additional analyses have been performed to quantitatively evaluate the performance of all of them showing as in this case DP techniques outperform the SP ones. The outcomes are then discussed taking into account both the features of each technique and the investigated scenario. Detecting and mapping this kind of phenomena is important for the evaluation of the affected area, especially for complex scenarios such as Ischia island, and can be very useful to support both the stakeholders for the first aid and the Civil Protection for the post-crisis management.

The Fucino Pliocene-Quaternary extensional basin represents a puzzling tectonic structure in the central part of the Apennine chain (Italy). Bordered by seismogenetic faults responsible for strong earthquakes in the last millennium (Mw = 6–7), differently from other elongated intermontane basins in this area, it has a rounded shape and extends for 15–20 km both in the E-W and N-S directions. This structural peculiarity is also demonstrated by the very intense gravity low, with amplitude >30 mGal (e.g., Cella et al., 2021), associated with this basin. Available reflection seismic data in this area are often considered of low quality (e.g., Compagnia Mediterranea Idrocarburi, 1999), and no deep well (i.e., >200 m depth) is present in this basin, so that its structure at depth results poorly constrained. In a recent paper, Mancinelli et al. (2021; hereafter this paper will be referred to as MSPM), by forward modelling residual gravity data try to confirm a recent 2D seismic stratigraphic interpretation (Patruno and Scisciani, 2021) and the relative model of the Fucino basin structure. In this interpretation of seismic data, the Pliocene-Quaternary units infilling the basin overlies an older (Messinian) siliciclastic flysch, instead of a carbonate substrate as hypothesized in previous studies (e. g., Cavinato et al., 2002; Cella et al., 2021). The forward gravity modelling attempted in MSPM would confirm the presence of huge volumes of Miocene sediments, with a thickness up to 1000 m, and would support the hypothesis of the presence of a, rapidly filled, transient Messinian foredeep basin. However, we have concerns about the quality of the gravity modelling proposed in MSPM, and consequently we are doubtful about the geological conclusions that are drawn from it.

After more than forty years since the 1980 Irpinia-Lucania earthquake, with this Special Issue “The November 23rd, 1980 Irpinia-Lucania, Southern Italy Earthquake: Insights and Reviews 40 Years Later” we revisit this milestone geological and seismological event, bringing together the latest views and news on this earthquake, with the aim of improving the dissemination of wide-ranging information on this remarkable case history.

On 29 December 2020, a shallow earthquake of magnitude Mw 6.4 struck northern Croatia, near the town of Petrinja, more than 24 hours after a strong foreshock (Ml 5). We formed a reconnaissance team of European geologists and engineers, from Croatia, Slovenia, France, Italy and Greece, rapidly deployed in the field to map the evidence of coseismic environmental effects. In the epicentral area, we recognized surface deformation, such as tectonic breaks along the earthquake source at the surface, liquefaction features (scattered in the fluvial plains of Kupa, Glina and Sava rivers), and slope failures, both caused by strong motion. Thanks to this concerted, collective and meticulous work, we were able to document and map a clear and unambiguous coseismic surface rupture associated with the main shock. The surface rupture appears discontinuous, consisting of multi-kilometer en échelon right stepping sections, along a NW-SE striking fault that we call the Petrinja-Pokupsko Fault (PPKF). The observed deformation features, in terms of kinematics and trace alignments, are consistent with slip on a right lateral fault, in agreement with the focal solution of the main shock. We found mole tracks, displacement on faults affecting natural features (e. g. drainage channels), scarplets, and more frequently breaks of anthropogenic markers (roads, fences). The surface rupture is observed over a length of ∼13 km from end-to-end, with a maximum displacement of 38 cm, and an average displacement of ∼10 cm. Moreover, the liquefaction extends over an area of nearly 600 km² around the epicenter. Typology of liquefaction features include sand blows, lateral spreading phenomenon along the road and river embankments, as well as sand ejecta of different grain size and matrix. Development of large and long fissures along the fluvial landforms, current or ancient, with massive ejections of sediments is pervasive. These features are sometimes accompanied by small horizontal displacements. Finally, the environmental effects of the earthquake appear to be reasonably consistent with the usual scaling relationships, in particular the surface faulting. This rupture of the ground occurred on or near traces of a fault that shows clear evidence of Quaternary activity. Further and detailed studies will be carried out to characterize this source and related faults in terms of future large earthquakes potential, for their integration into seismic hazard models.

In this paper, we investigated ground motion directional amplification and horizontal polarization using ambient noise measurements performed in the northern sector of Ischia Island which suffered damage (VIII EMS) during the 21 August 2017, Md 4.0 earthquake. Over 70 temporary seismic stations were installed by the INGV EMERSITO task force, whose aim is to monitor site effects after damaging earthquakes in Italy. To investigate ground motion directional amplification effects, we have applied three different techniques, testing their performance: the HVSR calculation by rotating the two horizontal components, the covariance matrix analysis, and time–frequency domain polarization analysis. These techniques resulted in coherent outcomes, highlighting the occurrence of directional amplification and polarization effects in two main sectors of the investigated area. Our results suggest an interesting pattern for ground motion polarization, that is mainly controlled by recent fault activity and hydrothermal fluid circulation characterizing the northern sector of the Ischia Island.