Anthropogenic sinkholes of the city of Naples, Italy: an update

In recent years, the study of anthropogenic sinkholes in densely urbanized areas has attracted the attention of both researchers and land management entities. The city of Naples (Italy) has been frequently affected by processes generating such landforms in the last decades: for this reason, an update of the sinkhole inventory and a preliminary susceptibility estimation are proposed in this work. Starting from previous data, not modified since 2010, a total of 270 new events occurred in the period February 2010–June 2021 were collected through the examination of online newspapers, local daily reports, council chronicle news and field surveys. The final consistence of the updated inventory is of 458 events occurred between 1880 and 2021, distributed through time with an increasing trend in frequency. Spatial analysis of sinkholes indicates a concentration in the central sector of the city, corresponding to its ancient and historic centre, crossed by a dense network of underground tunnels and cavities. Cavity-roof collapse is confirmed as one of the potential genetic types, along with processes related to rainfall events and service lines damage. A clear correlation between monthly rainfall and the number of triggered sinkholes was identified. Finally, a preliminary sinkhole susceptibility assessment, carried out by Frequency Ratio method, confirms the central sector of city as that most susceptible to sinkholes and emphasizes the predisposing role of service lines, mostly in the outermost areas of the city

SINKHOLES OF THE FRIULI VENEZIA GIULIA REGION: CHARACTERIZATION, DATA COLLECTION AND HAZARD DEFINITION

Il dottorato di ricerca si è focalizzato sull’identificazione, la caratterizzazione e l’analisi dei fenomeni di sinkhole (subsidence sinkhole sensu Gutiérrez et al., 2014) al fine di calcolare le distanze di rispetto e di sviluppare un protocollo informatico in grado di assegnare automaticamente a ciascun fenomeno la sua pericolosità. La regione Friuli Venezia Giulia (FVG) è stata scelta come area studio in quanto assieme al Carso Classico rappresenta un’area ricca di fenomeni di sprofondamento verificatisi in diversi contesti geologici. Un vasto censimento dei fenomeni presenti sul territorio regionale è stato fatto negli anni grazie ai diversi Accordi di ricerca tra il Servizio Geologico della regione e il Dipartimento di Matematica e Geoscienze dell'Università di Trieste al fine di implementare, con i fenomeni naturali, il geodatabase già esistente a livello nazionale. Il primo lavoro svolto all’interno del dottorato è stato quello di revisionare la struttura della banca dati, aggiornare le informazioni al suo interno e censire nuovi fenomeni in diversi contesti geomorfologici e litologici (inizialmente il censimento riguardava solo l’ambiente evaporitico). Tutto questo è stato possibile grazie agli innumerevoli sopralluoghi che hanno contribuito alla riduzione dei fenomeni "non definiti" (da 446 nel 2020 a 262 nel 2023), alla compilazione e/o all’aggiornamento di alcuni campi come la classificazione e, quando possibile, lo stato di attività e i parametri morfometrici, e all’aggiunta di 159 nuovi fenomeni. Il censimento si è concentrato in particolare sui carbonati a partire dal Carso Classico, e successivamente l'analisi è stata estesa a tutto il territorio regionale. La presenza di numerose grotte i cui ingressi possono essere riconducibili a dei collassi ha determinato la scelta di analizzare il catasto speleologico della regione FVG (CSR), esaminando un totale di 8004 grotte e definendo un protocollo metodologico per l’identificazione dei sinkhole in questo contesto. Parallelamente a quanto descritto, sono stati effettuati degli studi approfonditi su diverse aree test (es. abitati di Quinis e Baus (UD)) che hanno permesso di definire la miglior metodologia per caratterizzare questi fenomeni in diversi contesti geologico/geomorfologici. L'applicazione di diverse metodologie, come la combinazione di analisi di dati interferometrici e di livellamento, indagini geofisiche ecc., si è dimostrata fondamentale, non solo per la caratterizzazione tridimensionale di alcune forme, ma anche per l’analisi della loro evoluzione nel tempo evidenziando l'importanza del monitoraggio in continuo al fine di evitare danni ad abitazioni ed infrastrutture. Nell'area di Quinis sono state inoltre effettuate indagini di dettaglio tramite lo scavo di una trincea attraversando un sinkhole attivo. Questo studio, effettuato per la prima volta in Italia, ha permesso di descrivere e caratterizzare tridimensionalmente il fenomeno e l’area circostante. Tutte le attività svolte hanno portato allo sviluppo di un approccio metodologico in grado di definire automaticamente le distanze di rispetto dai sinkhole. Nella letteratura non esiste un metodo specifico per calcolarne il valore. Nel caso della regione FVG, è stato deciso di applicare una metodologia quantitativa basata sui dati disponibili raccolti nel geodatabase. In base allo stato di attività, alla classificazione e alla litologia, criteri specifici basati sul calcolo trigonometrico e sulle caratteristiche intrinseche del materiale coinvolto, hanno portato al calcolo di un buffer e all'assegnazione di una pericolosità a ciascuna area individuata. La metodologia è stata successivamente importata in ambiente GIS sviluppando un tool ad hoc applicabile ai fenomeni legati all'ambiente evaporitico per creare una mappa di pericolosità

Land use and land cover dynamics in Leiria City: relation between peri-urbanization processes and hydro-geomorphologic disasters

The objective of the present study is to evaluate the relation between the spatial and temporal dynamics of Land Use and Land Cover (LULC) and the hydro-geomorphological processes and their impacts. The study area is the city of Leiria, in central Portugal, within the period 1958–2018 based on the historical record of floods and landslides disasters. The LULC analysis shows an accentuated increase in the artificial areas and a continuous decrease in the agricultural areas. With regard to hydro-geomorphologic disaster occurrences, a total of 124 occurrences were identified, having caused a set of impacts. The obtained results allow one to characterize the artificialization process, its intensity and territorial dispersion, as a consequence of urban sprawl and peri-urbanization, along with its consequences in exposure to hydro-geomorphological processes. The analysis concludes that changing the risk drivers resulted in an increase in frequency and spatial dispersion of hydro-geomorphologic disasters over the analysed period.N/

Morphometry and evolution of sinkholes on the western shore of the Dead Sea. Implications for susceptibility assessment

Sinkhole development is a hazardous geomorphic process responsible for increasing economic losses worldwide. The highly dynamic eogenetic salt karst of the Dead Sea is one of the most striking examples of a human-enhanced sinkhole hazard. Since the 1980s, the shores of the Dead Sea have been affected by thousands of sinkholes while the lake level has been declining. Sinkholes pose a major threat, but their rapid development also offers an exceptional opportunity to study their evolution. Although the evolution of the morphometry and distribution of sinkholes provides essential data for hazard assessment, this kind of studies are almost lacking because of the typical slowness of the processes. Here we present multi-temporal cartographic sinkhole inventories of a sector in the western shore of the Dead Sea. The database was constructed using aerial and satellite imagery, high-resolution three-dimensional photogrammetric models, and fieldwork. Most of the depressions mapped were single, small, relatively shallow, subcircular, collapse sinkholes nested within large sagging basins. From 2005 to 2021, the 702 new sinkholes have been concentrated along a narrow N-S-oriented strip comprising tightly packed alignments and clusters. Sinkhole expansion by mass wasting and coalescence play an essential role in the evolution of the sinkhole landscape. An average subsidence rate of 45 cm/year has been calculated for the total area affected by sinkholes, providing an indirect estimate for the rate of subsurface salt dissolution. This research illustrates how multi-temporal geomorphic mapping and morphometric analyses provide an objective basis for the development of reliable spatial predictions for sinkhole evolution

Natural and Technological Hazards in Urban Areas

Natural hazard events and technological accidents are separate causes of environmental impacts. Natural hazards are physical phenomena active in geological times, whereas technological hazards result from actions or facilities created by humans. In our time, combined natural and man-made hazards have been induced. Overpopulation and urban development in areas prone to natural hazards increase the impact of natural disasters worldwide. Additionally, urban areas are frequently characterized by intense industrial activity and rapid, poorly planned growth that threatens the environment and degrades the quality of life. Therefore, proper urban planning is crucial to minimize fatalities and reduce the environmental and economic impacts that accompany both natural and technological hazardous events

Establishing a tracer-based sediment budget to preserve wetlands in Mediterranean mountain agroecosystems (NE Spain)

Pags.- 5 Figs.- 2 Tabls.- Suppl. Materials. The definitive version is available at: http://www.sciencedirect.com/science/journal/00489697Mountain wetlands in Mediterranean regions are particularly threatened in agricultural environments due to anthropogenic activity. An integrated study of source-to-sink sediment fluxes was carried out in an agricultural catchment that holds a small permanent lake included in the European NATURA 2000 Network. More than 1000 yrs of human intervention and the variety of land uses pose a substantial challenge when attempting to estimate sediment fluxes which is the first requirement to protect fragile wetlands. To date, there have been few similar studies and those that have been carried out have not addressed such complex terrain. Geostatistical interpolation and GIS tools were used to derive the soil spatial redistribution from point 137Cs inventories, and to establish the sediment budget in a catchment located in the Southern Pyrenees. The soil redistribution was intense and soil erosion predominated over soil deposition. On the areas that maintained natural vegetation the median soil erosion and deposition rates were moderate, ranging from 2.6 to 6 Mg ha yr− 1 and 1.5 to 2.1 Mg ha yr− 1, respectively. However, in cultivated fields both erosion and deposition were significantly higher (ca. 20 Mg ha yr− 1), and the maximum rates were always associated with tillage practices. Farming activities in the last part of the 20th century intensified soil erosion, as evidenced by the 1963 137Cs peaks in the lake cores and estimates from the sediment budget indicated a net deposition of 671 Mg yr− 1. Results confirm a siltation risk for the lake and provide a foundation for designing management plans to preserve this threatened wetland. This comprehensive approach provides information useful for understanding processes that influence the patterns and rates of soil transfer and deposition within fragile Mediterranean mountain wetlands subjected to climate and anthropogenic stresses.We thank the CICYT project EROMED (CGL2011-25486) for the financial support.Peer reviewe

Deformed archaeological remains at Lilybaeum in Western Sicily (southern Italy): possible ground signatures of a missed large earthquake

Archaeoseismic analysis performed in Western Sicily points to deformed archeological remains at Lilybaeum, a Punic coastal city founded in 397 B.C. at the Island’s westernmost edge. Starting from the direct observation of deformed ruins, an interdisciplinary work strategy, which included field-structural analysis, drone-shot high-resolution aerial photogrammetry, and geophysical prospecting, was employed to investigate whether the identified deformations may represent the ground effects of a previously unknown large earthquake in the area. Among the unearthed remains, some mosaics and a stone-paved monumental avenue show evidence of tectonic deformation, being fractured, folded, and uplifted. The trend of folding and fracturing is consistent with the NNW–SSE oriented tectonic max stress axis to which Western Sicily is currently subjected. Displacement along a fracture deforming the Decumanus Maximus together with the finding of a domino-type directional collapse, enable us to interpret the observed deformation as the ground signature of a coseismic slip. The seismic rupture occurred along a previously unmapped deformation front that fits well within the seismotectonic context of Western Sicily. Measured offset, geophysical prospecting, and age-constraints all suggest the possibility that a highly-energetic earthquake nucleated in the area following a coseismic rupture along a NE–SW trending back-verging reverse fault towards the end of the fourth century CE. Since seismic catalogs do not provide evidence of such a large earthquake, this event might represent a missed entry in the historical seismic record. This finding provides constraints to redefine the seismic hazard of Western Sicily, a region where recurrence-time intervals for large earthquakes are still unknown