Anthropogenic Sinkhole

Soft highly porous carbonate rocks such, as calcarenites, and soluble sulphate rocks, as gypsum, are very common in the Mediterranean region and, due to their microstructure and chemical composition, are prone to water induced weathering mechanisms. Cliffs, underground cavities and other morphological features in such formations are hence affected by intense erosion phenomena and weathering processes responsible of unexpected collapses and sinkholes. Just considering the Apulian region (Italy), 150 sinkholes have been recorded since 1925, with increasing frequency since 2000 . The geosystem's failure is often the short or long-term result of a very complex hydro-chemo mechanical process taking place at the micro-scale which can be detected and analysed by means of field and laboratory experimental test campaigns. Therefore, stability problems are often related to changes of the mechanical properties of the rock forming the cave caused by environmental weathering processes, despite the external boundary conditions are not changing with time. The paper deals with the assessment of hazard associated to the stability of abandoned underground caves, which is nowadays frequently required for land and urban planning activities. A methodological approach for hazard assessment based on a step-by-step procedure is proposed. This includes in-situ surveys, laboratory experimental studies, theoretical analyses and finally numerical investigations. The approach derives from the experience developed from several case studies analysed by the authors. In this work, two of these are presented. The first one concerns the stability of an anthropic cavity in a calcarenite formation which is affected by a water induced short-term and long-term debonding processes. The second one regards the stability of a three-

Risk perception is judgment that people make about the characteristics and severity of risks, in last few years risk perception studies focused on provide cognitive elements to communication experts responsible in order to design citizenship information and awareness appropriate strategies. Several authors in order to determine natural hazards risk (Seismic, landslides, cyclones, flood, Volcanic) perception used questionnaires as tool for providing reliable quantitative data and permitting comparison the results with those of similar surveys. In Italy, risk perception studies based on surveys, were also carried out in order to investigate on national importance Natural risk, in particular on Somma-Vesuvio and Phlegrean Fields volcanic Risks, but lacked risk perception studies on local situation distributed on whole national territory. National importance natural hazard were frequently reported by national mass media and there were debate about emergencies civil protection plans, oth...

The extraction of ore and minerals by underground mining often causes ground subsidence phenomena and may result in severe damage to buildings. Risk analysis in subsidence regions requires the assessment of both the hazards to and vulnerability of nearby buildings. However, many uncertainties exist and this assessment and its representation as well are still a complex objective. For this purpose a damage simulation tool is developed to investigate hazard and vulnerability under several possible scenarios of mining subsidence in which a large number of buildings may be affected. Ground movements assessment is based on the influence function method, and building damage is estimated using vulnerability functions. A case study is presented to illustrate the different results given by the damage simulator. Uncertainties about the collapsed zone of the mine and influence angles lead to the definition of different possible scenarios. A relative occurrence probability is then defined to implement a probabilistic approach to the hazard and vulnerability assessments. Different results, more or less synthetics, can then be obtained to assess both hazard and vulnerability over the exposed city. These results are compared and the maximal horizontal ground strains and the mean damage appear to be the most effective and relevant way to address the question. A final ranking based on scoring is then provided.

In Campania (southern Italy), the widespread presence of anthropogenic cavities in the subsoil of the Neapolitan and Caserta provinces is well known. In these towns, the underground quarrying activities were performed for centuries to extract volcanic tuffs for buildings. The urban developments have sealed many signals of the presence of cavities and their real extent is almost unknown, thus representing a geological hazard and contributing to the subsoil instability of many places. This contribution will show the main cavity typologies recognized across an area north of Naples according to the geological characteristics of the subsoil. The main aim of the study is the cataloging of the cavities and the analysis of the city subsoil as their presence may easily trigger the collapse of the shallow or deeper soils. Moreover, the recognition and sustainable reuse of cavities contributes to enhancing the cultural and touristic promotion of a territory. In this study, a database framework...

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Within the PanGeo project (financed by the European Commission under the 7th Framework Program), the Geological Survey of Italy (ISPRA) and the Urban Planning Department of the City of Roma developed a geodatabase and map of the geological hazards for the territory of Roma, integrating remotely sensed data (PSInSAR-Permanent Scatterer Interferometry Synthetic Aperture Radar) and in situ geological information. Numerous thematic layers, maps and inventories of hazards (e.g., landslides, sinkholes, cavities), geological and hydrogeological data added to historical and recent urbanization information were compared to the permanent scatterer (PS) data from the European Remote Sensing satellites (ERS-1/2, 1992-2000) and ENVISAT (2002-2005) descending scenes, in order to produce a ground stability layer (GSL). Based on the PS data, most of the territory appears stable (almost 70 % of PS velocities are within ±1 mm/year). About 14 % of the PSs show positive line-of-sight (LOS) velocities (measured along the LOS of the satellite) between 1 and 3 mm/year and more than 2 % exceed 3 mm/year; more than 11 % of PSs show negative LOS velocities between-1 and-3 mm/year, while about 3 % exceed-3 mm/ year (with tens of the PSs showing velocities over-20 mm/year). The GSL is comprised of polygons or multi-polygons (multipart polygons grouping individual polygons under a single identifier geohazard) enclosing areas where geohazards have been pointed out by PS data and/or in situ surveys (observed instabilities), and by polygons enclosing areas potentially affected by geohazards, based on the available knowledge of the territory (potential instabilities). In Roma's GSL, 18 multi-polygons (covering ca. 600 km 2) related to observed instabilities have been outlined, where ground movements could be detected through InSAR data or where landslides and sinkholes are known to have occurred. Other 13 multi-polygons (covering nearly 900 km 2) concern areas where the potential occurrence of geohazards was inferred by combining geological and/or geothematic data (potential instabilities). The geohazards mapped in Roma have been: landslides, collapsible grounds, compressible grounds, groundwater abstraction, mining, man-made ground, tectonic movements, and volcanic inflation/deflation. The lattermost is the likely cause of the significant uplift observed in the Alban Hills area. However, this paper focuses on two more currently impending hazards: subsidence and sinkholes. In general, sinkhole-prone areas (areas of dense underground cavities) are hard to discern from satellite data, but can be revealed by ruling out other potential causes of observed ground movement based on in situ data. Subsiding zones are effectively detected by the available PSInSAR dataset over a total extent of about 60 km 2 , mostly overlapping the recent alluvial areas of the Tiber and its tributaries. PSs show a very different behaviour inside and outside the historical centre. Inside, loading by anthropogenic construction and man-made ground since ancient times has led to an almost complete consolidation of the recent river deposits, marked by modest to absent subsidence. In contrast, outside, subsidence clearly stands out, with negative LOS velocities that, although generally within several mm/year, can locally exceed-25 mm/ year. PS data have provided motion information at both a regional and local scale (up to the scale of a single building). Closer to the sea, in the Tiber delta area, velocities increase, especially above recently reclaimed marsh areas, rich in peat and organic clays. Velocities can change significantly over short distances, as in the international airport area, reflecting the local stratigraphic setting. The same occurs in the two subsiding areas located within the Alban Hills volcanic complex, which is generally affected by ground uplift. As a whole, PSInSAR ground motion velocities offer a significant contribution to susceptibility and hazard recognition studies. In particular, such a method provides a fast and effective tool available to local authorities to monitor ground and building behaviour, possibly allowing for timely prevention activities, especially when coupled with appropriate in situ knowledge.

Geological phenomena vary in space and time, a trait that makes geology a very suitable application field for Geographical Information Systems and science (GIS). A GIS is a computer-based tool for the mapping, display and analysis of entities and events on Earth, which has transformed the working lives of geoscientists, especially over the last 10-15 years. Here the basic concepts and functionality of GIS which are most relevant to the work of a geologist are briefly described and some examples are given, as well the scope and limitations of some of the software tools currently available. GIS touches on everyone's lives in some way today and there are myriad other applications fields. From grass roots field mapping and spatial modeling to data management and market predictions, GIS has important roles in the everyday lives of geologists, geophysicists and geographer.

Ancient mining and quarrying activities left anthropogenic geomorphologies that have shaped the natural landscape and affected environmental equilibria. The artificial structures and their related effects on the surrounding environment are analyzed here to characterize the quarrying landscape in the southeast area of Rome in terms of its dimensions, typology, state of preservation and interface with the urban environment. The increased occurrence of sinkhole events in urban areas has already been scientifically correlated to ancient cavities under increasing urban pressure. In this scenario, additional interacting anthropogenic factors, such as the aerial bombardments perpetrated during the Second World War, are considered here. These three factors have been investigated by employing a combined geomatic methodology. Information on air raids has been organized in vector archives. A dataset of historical aerial photographs has been processed into Digital Surface Models and orthomosaic...

In Campania (southern Italy), the widespread presence of anthropogenic cavities in the subsoil of the Neapolitan and Caserta provinces is well known. In these towns, the underground quarrying activities were performed for centuries to extract volcanic tuffs for buildings. The urban developments have sealed many signals of the presence of cavities and their real extent is almost unknown, thus representing a geological hazard and contributing to the subsoil instability of many places. This contribution will show the main cavity typologies recognized across an area north of Naples according to the geological characteristics of the subsoil. The main aim of the study is the cataloging of the cavities and the analysis of the city subsoil as their presence may easily trigger the collapse of the shallow or deeper soils. Moreover, the recognition and sustainable reuse of cavities contributes to enhancing the cultural and touristic promotion of a territory. In this study, a database framework...

This study aims to investigate an unpublished case of a large complex of quarries in Polignano a Mare (southern Italy), a few metres from the coast of the Adriatic Sea, which was in use until the middle of the 20th century and is now abandoned. Due to the extensive mining activities, the gradual transformation of the calcarenite and limestone bedrock, not only affected the rock faces of the nearby lama, but also resulted in the creation of an
extensive network of hypogeal spaces, which have pierced the rocky vein for hundreds of metres, creating suggestive underground environments. Through the study of the data obtained from the metrological analysis of the quarry stepped faces and their comparison with the standard sizes of ashlars used in local architecture as well as information contained in historical documents and in ancient maps, this investigation aims also to
understand the reasons behind the choice of this site, the identification of its chronological framework and the quarrying techniques involved. On the surface, the study of the marks left on the ground by the passage of carts for the transport of extracted material shed light on the entire production cycle, from extraction to transport.
In addition to providing construction material, the quarry shows traces of settlement that would suggest that some areas of the site were inhabited, probably by the quarrymen themselves or later by local shepherds, as evidenced by the presence of Christian crosses and troughs carved into the rock which also could help to reconstruct the social history of this area.

Many built-up areas of Sicily (southern Italy) are affected by such type of risk. In particular, Marsala (western end of Sicily, Figure 1) was affected in the past decades by several collapse phenomena which caused extensive damage to infrastructures and population. These phenomena are related to the presence of underground quarries for the extraction of calcarenites used as building materials. These cavities are carved at depth varying from several meters to roughly 25 m on a single or superimposed layer, following the excavation techniques of chambers and passages separated by rock pillars. However, excavation typically occurred without any planning. With time, the underground quarries were progressively abandoned for several reasons (i.e., interaction with the percolating waters, decay of the physical-mechanical properties of the rock, high costs, difficulties and risk excavation work). Nowadays in many cavities signs of instability can be clearly recognized along ceilings, walls and pillars. These instabilities easily propagate upwards causing sinkhole and subsidence phenomena according to the mechanisms described in Parise & Lollino (2011), thus creating consistent damages to buildings and infrastructures. A sinkhole, occurred in June 2011 and related to an underground quarry in the eastern sector of Marsala, is described in this paper as a case study (Figure 2). The site was selected for the availability of topographic data of the underground quarry, prior to the formation of the

Sinkhole development occurs in many areas of the world where soluble rocks crop out. Sinkholes are generally the surface expression of the presence of caves and other groundwater flow conduits in carbonate rocks, which are solutionally enlarged secondary permeability features. Their formation may be either natural or caused by man's activities. In both cases, heavy consequences have to be registered on the anthropogenic environment and related infrastructures. Knowledge of the mechanism of formation of this subtle geohazard is therefore necessary to planners and decision makers for performing the most appropriate and suitable programs of land use and development. The Apulia region of southern Italy is characterized for most of its extension by carbonate rocks, which makes it one of the most remarkable example of karst in the Mediterranean Basin. Based on analysis of literature and in situ surveys, including caving explorations, we have identified in Apulia three main types of possible mechanisms for sinkhole formation: 1) collapse of a chamber in a natural cave or in man-made cavities; 2) slow and gradual enlargement of doline through dissolution; 3) settlement and internal erosion of filling deposits of pre-existing dolines. Since sinkhole formation very often affects directly the human settlements in Apulia, and have recently produced severe damage, some considerations are eventually presented as regards the interrelationships between sinkholes and the anthropogenic environment.

The UK is perhaps unique globally in that it presents the full spectrum of geological time, stratigraphy and associated lithologies within its boundaries. With this wide range of geological assemblages comes a wide range of geological hazards, whether geophysical (earthquakes, effects of volcanic eruptions, tsunami, landslides), geotechnical (collapsible, compressible, liquefiable, shearing, swelling and shrinking soils), geochemical (dissolution, radon and methane gas hazards) or related to georesources (coal, chalk and other mineral extraction). An awareness of these hazards and the risks that they pose is a key requirement of the engineering geologist. This volume sets out to define and explain these geohazards, to detail their detection, monitoring and management, and to provide a basis for further research and understanding, all within a UK context.

Many large collapses have occurred during or after underground quarry operations. The collapse of the Clamart underground quarry (in 1961, South of Paris-France) is well known as one of the most catastrophic. This paper presents a back-analysis of the case study using an empirical approach. Based on a set of assumptions, the empirical approach has indicated a reliable scenario that may explain the collapse: the large collapse may have been caused by a lack of bearing capacity of the pillars and the sudden failure of a hard limestone bed in the roof, the load on which would have been concentrated until overload occurred. The bed weakness between the two quarrying levels may also have had an influence on the general lack of stability of the quarry. Moreover, under the given hypothesis, the study shows a very low influence of the water table due to flooding of the underground quarry. RÉSUMÉ Les effondrements peuvent affecter les cavités souterraines pendant et après le creusement. L'effondrement historique en 1961 de la carrière de Clamart (sud de Paris-France) est connu comme le plus catastrophique. Cet article présente une rétro-analyse basée sur une approche analytique-empirique. Les résultats ont montré que la cause principale de l'effondrement est l'insuffisance de la résistance des piliers et la rupture brutale du banc de calcaire du haut toit. Les piliers ont été stables grâce à la présence du banc de calcaire dans le toit. D'autres facteurs comme l'ennoyage et la rupture de l'intercalaire ont également contribué à l'effondrement, avec un rôle moins important.

This work presents a sinkhole susceptibility and risk assessment mapping in Guidonia-Bagni di Tivoli plain (Italy), a travertine sinkhole-prone area where sudden occurrences of sinkholes have happened in past and recent times. We collected a point-like sinkhole inventory and we considered a series of different sinkholecontrolling and precursory factors over the study area, related to its geo-litho-hydrological setting and to its terrain deformational scenario, i.e. ground motion rates derived from InSAR COSMO-SkyMed imagery. A sinkhole susceptibility map was produced through a machine learning model, namely Maximum Entropy algorithm (MaxEnt). Results highlight that the most determining factors for sinkhole formation are the lithology, the travertine thickness, groundwater and the land use. The sinkhole susceptibility map was then combined with data on vulnerability and elements-at-risk economic exposure in order to provide a sinkhole risk map of the area. The outcomes show that areas at higher risk covers about 2% of the total study area and primarily relies on the zoning of the main urban fabric. In particular, it is worth to highlight that 5% of the whole road-network pavement and 27% of all the residential buildings fall into High and Very High risk classes. Overall, results of this work demonstrate capabilities of machine learning models to assess sinkhole susceptibility for predicting potential sinkhole areas, and provide a sinkhole risk map, along with information on urban environment, as a useful tool for urban planning and geohazard risk management.

All activities used to identify the underground quarries, recognize the corresponding sinkhole-prone areas at the surface, survey the cavities, produce detailed maps, and reclaim the sites in order to allow future development, are described in this paper, as an example of how to properly manage a territory characterized by sinkhole problems.

Sinkhole development occurs in many areas of the world where soluble rocks crop out. Sinkholes are generally the surface expression of the presence of caves and other groundwater flow conduits in carbonate rocks, which are solutionally enlarged secondary permeability features. Their formation may be either natural or caused by man's activities. In both cases, heavy consequences have to be registered on the anthropogenic environment and related infrastructures. Knowledge of the mechanism of formation of this subtle geohazard is therefore necessary to planners and decision makers for performing the most appropriate and suitable programs of land use and development. The Apulia region of southern Italy is characterized for most of its extension by carbonate rocks, which makes it one of the most remarkable example of karst in the Mediterranean Basin. Based on analysis of literature and in situ surveys, including caving explorations, we have identified in Apulia three main types of possible mechanisms for sinkhole formation: 1) collapse of a chamber in a natural cave or in man-made cavities; 2) slow and gradual enlargement of doline through dissolution; 3) settlement and internal erosion of filling deposits of pre-existing dolines. Since sinkhole formation very often affects directly the human settlements in Apulia, and have recently produced severe damage, some considerations are eventually presented as regards the interrelationships between sinkholes and the anthropogenic environment.

Internal degradation induced in the metropolitan areas by leakage of sewers. As the resistance to erosion depends on the distribution of soil particles and the water pressure in sewer pipes, it is worthwhile to research the impact of water pressure on the soil erosion resistance of embedded pipes. This study aims to find physical model tests which simulating erosion and sinkhole development due to cyclic leakage in an experimental ground model through defect sewers. Proposed parameters like cyclic leaks through pipe crashes, eroded soil properties, initiation cavity, and evolution up until sinkhole failure were studied. During this process, the ground settlement monitored with Paricle:Image Velocimetry (PIV). Also, soils with various classification were utilized to identify the total subsidence for the different soil types. Five various water pressures were used:i.e., 0.8,1.1,1.4,1.7, and 2.0 meter,(7.85, 10.79, 13.73, 16.76, and 19.61 Kpa), respectively, and local sandy soil, local...

This work presents a sinkhole susceptibility and risk assessment mapping in Guidonia-Bagni di Tivoli plain (Italy), a travertine sinkhole-prone area where sudden occurrences of sinkholes have happened in past and recent times. We collected a point-like sinkhole inventory and we considered a series of different sinkholecontrolling and precursory factors over the study area, related to its geo-litho-hydrological setting and to its terrain deformational scenario, i.e. ground motion rates derived from InSAR COSMO-SkyMed imagery. A sinkhole susceptibility map was produced through a machine learning model, namely Maximum Entropy algorithm (MaxEnt). Results highlight that the most determining factors for sinkhole formation are the lithology, the travertine thickness, groundwater and the land use. The sinkhole susceptibility map was then combined with data on vulnerability and elements-at-risk economic exposure in order to provide a sinkhole risk map of the area. The outcomes show that areas at higher risk covers about 2% of the total study area and primarily relies on the zoning of the main urban fabric. In particular, it is worth to highlight that 5% of the whole road-network pavement and 27% of all the residential buildings fall into High and Very High risk classes. Overall, results of this work demonstrate capabilities of machine learning models to assess sinkhole susceptibility for predicting potential sinkhole areas, and provide a sinkhole risk map, along with information on urban environment, as a useful tool for urban planning and geohazard risk management.

The underground exploitation of calcarenitic rocks, it's not uncommon especially in cases where the calcarenites doesn't outcrop. This activity caused evident phenomena of subsidence in surface with damages to the belongings and people too. In the present note, some Italian cases are outlined, over all for as concerns the geometric characteristics of the mining that strongly influence the stability of single structural elements (pillar, roofs) and of the mine in its whole. Particularly, as regards the shape of the pillars and the excavated tunnels, it is noted that their irregularity facilitates instability, which also increases with the age of the quarry. It's of fundamental importance, an unfavourable orientation of exavation with respect to the structural characteristics of the area, like in Mottola (Italy), where there have also been problems of the decay of the physical and mechanical rock characteristics because of the metoric water drainage in the quarry.

The extraction of ore and minerals by underground mining often causes ground subsidence phenomena and may result in severe damage to buildings. Risk analysis in subsidence regions requires the assessment of both the hazards to and vulnerability of nearby buildings. However, many uncertainties exist and this assessment and its representation as well are still a complex objective. For this purpose a damage simulation tool is developed to investigate hazard and vulnerability under several possible scenarios of mining subsidence in which a large number of buildings may be affected. Ground movements assessment is based on the influence function method, and building damage is estimated using vulnerability functions. A case study is presented to illustrate the different results given by the damage simulator. Uncertainties about the collapsed zone of the mine and influence angles lead to the definition of different possible scenarios. A relative occurrence probability is then defined to implement a probabilistic approach to the hazard and vulnerability assessments. Different results, more or less synthetics, can then be obtained to assess both hazard and vulnerability over the exposed city. These results are compared and the maximal horizontal ground strains and the mean damage appear to be the most effective and relevant way to address the question. A final ranking based on scoring is then provided.

A reply essay is presented on the rebuttal article by Parise (Environ Earth Sci 75(23):1476, 2016) suggesting that qanat is not a hazard. It is presented as a refutation on the paper by Abbasnejad et al. (Environ Earth Sci 75:1306, 2016) in which the authors have explained the etiology, the impacts and remedies of a qanat hazard in Iranian urban areas. Since the majority of qanats in Iranian urban areas are abandoned, useless and threatening, according to definition and in comparison with similar features introduced as a hazard, they are considered as a hazard too. However, this does not mean, and Abbasnejad et al. (in Environ Earth Sci 75:1306, 2016) have not claimed, that all qanats are hazardous. In addition, the authors who have studied qanats in Iranian urban areas, before Abbasnejad et al. (in Environ Earth Sci 75:1306, 2016), have also considered qanats as a hazard.

All activities used to identify the underground quarries, recognize the corresponding sinkhole-prone areas at the surface, survey the cavities, produce detailed maps, and reclaim the sites in order to allow future development, are described in this paper, as an example of how to properly manage a territory characterized by sinkhole problems.

The underground exploitation of calcarenitic rocks, it's not uncommon especially in cases where the calcarenites doesn't outcrop. This activity caused evident phenomena of subsidence in surface with damages to the belongings and people too. In the present note, some Italian cases are outlined, over all for as concerns the geometric characteristics of the mining that strongly influence the stability of single structural elements (pillar, roofs) and of the mine in its whole. Particularly, as regards the shape of the pillars and the excavated tunnels, it is noted that their irregularity facilitates instability, which also increases with the age of the quarry. It's of fundamental importance, an unfavourable orientation of exavation with respect to the structural characteristics of the area, like in Mottola (Italy), where there have also been problems of the decay of the physical and mechanical rock characteristics because of the metoric water drainage in the quarry.

Historical records were used for the compilation of a database of sinkholes resulted from collapses of abandoned shallow underground limestone quarries (mines) in two villages in Belgian South Limburg. During the last 350 years the formation of such sinkholes caused at least 38 casualties, but more often it caused a change in topography and damage to public and private property. The objective of this study is to better understand the spatial and temporal patterns of quarry collapse-related sinkholes in the study area. Apart from sinkhole locations and ages, the compiled database provides information on the dimensions of the area affected and the damage caused by sinkhole formation, as well as the causal factors of sinkholes. One hundred seventy-three sinkholes have been reported since 1665, but most (80%) reported sinkholes postdate 1965. Sinkhole dimensions provided information on the type of collapse. Seven large sinkholes, displacing a total sediment volume of 480,000 m 3 , resulted from large-scale roof breakdown after pillar failure. The smaller sinkholes were the result of fall of the overburden into galleries after local roof collapse or suffosion of a solution pipe. In total, these small sinkholes displaced 12,300 m 3 of sediment. At present almost all large underground quarries in the study area have been affected by sinkholes. These features were caused by natural and anthropogenic factors, and occur in zones with thin roofs, where pillars were affected by pillar robbing, or on locations with inappropriate sewerage systems above quarries. The formation of sinkholes was often reported in spring during years with high moisture contents in the overburden, caused by high groundwater recharge or above average precipitation. With increasing time since quarry abandonment, quarries become more susceptible to pillar creep and bending of the roof. Hence, if no appropriate mitigation measures are taken to reduce such deterioration processes, the number of sinkholes is expected to increase.

This GeoHazard Description (GHD) was prepared by the Italian Geological Survey, a department of the Italian Institute for Environmental Protection and Research (ISPRA), and acts as support for the PanGeo Ground Stability Layer (GSL) of Palermo (intermediate product), Italy (www.pangeoproject.eu). The area covered by the GSL basically represents the administrative area of Palermo Municipality (ca. 159 km2), with the exception of a small appendix to the south. The LUZ (Larger Urban Zone) of Palermo is a much wider zone (nearly 8 times the GSL), which is covered by PS data only in a small portion slightly larger than the chosen GLS. The identification of geohazards was performed through combined interpretation of geological, land use and other geospatial layers available at ISPRA or provided by the technical offices of Palermo Municipality, together with satellite Persistent Scatterers (PS) ground motion data for the period April 1992- May 2001, derived by T.R.E. (Tele Rilevamento Euro...

It has been said that Palermo is short of available water. However, nothing could be more wrong. Well-documented Arab sources and narrative chronicles reported an abundance of groundwater resources in Palermo Plain since the Middle Ages. The scarcity of sources and surface water in the Palermo Plain, compared to the groundwater abundance, led the inhabitants to use groundwater both for irrigation and domestic usage through a complex and sustainable hydraulic system. Vertical and horizontal (qanāts) wells, conveyed water towards gardens and public fountains making the Arabic Bal'harm (Palermo) a flourishing town. When visitors walk through the streets of Palermo's historical center, among Arab ruins and Baroque architecture, they hardly imagine that there is a wide and varied cultural heritage of underground cavities hidden in the basements where water flows in intricate networks fed from a numerous springs. Only in recent years was a part of this system brought to light. Moreover, the city still has a wide

Abstract: It has been said that Palermo is short of available water. However, nothing could be more wrong. Well-documented Arab sources and narrative chronicles reported an abundance of groundwater resources in Palermo Plain since the Middle Ages. The scarcity of sources and surface water in the Palermo Plain, compared to the groundwater abundance, led the inhabitants to use groundwater both for irrigation and domestic usage through a complex and sustainable hydraulic system. Vertical and horizontal (qan􏰀ts) wells, conveyed water towards gardens and public fountains making the Arabic Bal’harm (Palermo) a flourishing town. When visitors walk through the streets of Palermo’s historical center, among Arab ruins and Baroque architecture, they hardly imagine that there is a wide and varied cultural heritage of underground cavities hidden in the basements where water flows in intricate networks fed from a numerous springs. Only in recent years was a part of this system brought to light. M...

The rising groundwater levels in Ajdabiya city have been considered one of the critical issues that the city suffered for years, where it is attributed to a lot of undesirable environmental and physical effects. Deterioration of infrastructure facilities led to health and economic consequences in different areas. The study aims to identify the causes effects and feasible strategies to mitigate them. There are Many causes led to rising the groundwater level such as the leakage of domestic water pipeline and sewage network. It noted an absence of a rainwater drainage network and the adoption of only surface water for daily life usages. Furthermore, never ever the groundwater has been not exploited, which led to upward seepage more and more. Ten groundwater samples have been collected to conduct specific criteria which proved the mixing between the groundwater and sewage. Many projects can be adapted to maintain the groundwater upward seepage and manage the water supplies in the area u...

The rising groundwater levels in Ajdabiya city have been considered one of the critical issues that the city suffered for years, where it is attributed to a lot of undesirable environmental and physical effects. Deterioration of infrastructure facilities led to health and economic consequences in different areas. The study aims to identify the causes of effects and feasible strategies to mitigate them. There are many causes that led to rising the groundwater level such as the leakage of domestic water pipeline and sewage network. It noted an absence of a rainwater drainage network and the adoption of only surface water for daily life usages. Furthermore, never ever the groundwater has been not exploited, which led to upward seepage more and more. Ten groundwater samples have been collected to conduct specific criteria which proved the mixing between the groundwater and sewage. Many projects can be adapted to maintain the groundwater upward seepage and manage the water supplies in th...

Urban geological hazards involving ground instability can be costly, dangerous, and affect many people, yet there is little information about the extent or distribution of geohazards within Europe's urban areas. A reason for this is the impracticality of measuring ground instability associated with the many geohazard processes that are often hidden beneath buildings and are imperceptible to conventional geological survey detection techniques. Satellite radar interferometry, or InSAR, offers a remote sensing technique to map mm-scale ground deformation over wide areas given an archive of suitable multi-temporal data. The EC FP7 Space project named PanGeo (2011-2014), used InSAR to map areas of unstable ground in 52 of Europe's cities, representing ~15% of the EU population. In partnership with Europe's national geological surveys, the PanGeo project developed a standardised geohazard-mapping methodology and recorded 1286 instances of 19 types of geohazard covering 18,000 km 2. Presented here is an analysis of the results of the PanGeo-project output data, which provides insights into the distribution of European urban geohazards, their frequency and probability of occurrence. Merging PanGeo data with Eurostat's GeoStat data provides a systematic estimate of population exposures. Satellite radar interferometry is shown to be as a valuable tool for the systematic detection and mapping of urban geohazard phenomena.

The Upper City of Antananarivo, is one of the districts of the capital of Madagascar subject to the regulations of the Architectural, Urban and Landscape Heritage Protection Zone [1]. On the other hand, the urbanization of this zone has not made it possible to curb the uncontrolled urbanization which is characterized by the spontaneity of illicit constructions caused in particular by the impoverishment of the local populations. Faced with this situation, the sanitation aspect of the area is no longer under control and all these phenomena have created a new type of exposure to risk through the degradation of the supporting soil and the triggering of fatal land movements. This urbanized area is subject to geotechnical risks that require reconnaissance on geological structuring, urbanization and problems observed to monitor the evolution of hazards. Technical studies of the Antananarivo upper town massif reveal instability and eventually hazards such as landslides, rock falls and block...

Classical rock mass classification systems are not applicable to carbonate rocks, especially when these are affected by karst processes. Their applications to such settings could therefore result in outcomes not representative of the real stressestrain behavior. In this study, we propose a new classification of carbonate rock masses for engineering purposes, by adapting the rock engineering system (RES) method by Hudson for fractured and karstified rock masses, in order to highlight the problems of implementation of geomechanical models to carbonate rocks. This new approach allows a less rigid classification for carbonate rock masses, taking into account the local properties of the outcrops, the site conditions and the type of engineering work as well.

Sinkhole development occurs in many areas of the world where soluble rocks crop out. Sinkholes are generally the surface expression of the presence of caves and other groundwater flow conduits in carbonate rocks, which are solutionally enlarged secondary permeability features. Their formation may be either natural or caused by man's activities. In both cases, heavy consequences have to be registered on the anthropogenic environment and related infrastructures. Knowledge of the mechanism of formation of this subtle geohazard is therefore necessary to planners and decision makers for performing the most appropriate and suitable programs of land use and development. The Apulia region of southern Italy is characterized for most of its extension by carbonate rocks, which makes it one of the most remarkable example of karst in the Mediterranean Basin. Based on analysis of literature and in situ surveys, including caving explorations, we have identified in Apulia three main types of possible mechanisms for sinkhole formation: 1) collapse of a chamber in a natural cave or in man-made cavities; 2) slow and gradual enlargement of doline through dissolution; 3) settlement and internal erosion of filling deposits of pre-existing dolines. Since sinkhole formation very often affects directly the human settlements in Apulia, and have recently produced severe damage, some considerations are eventually presented as regards the interrelationships between sinkholes and the anthropogenic environment.

All activities used to identify the underground quarries, recognize the corresponding sinkhole-prone areas at the surface, survey the cavities, produce detailed maps, and reclaim the sites in order to allow future development, are described in this paper, as an example of how to properly manage a territory characterized by sinkhole problems.

Underground voids of natural or anthropogenic origin potentially represent a serious hazard to the built-up areas. Urban development and construction of infrastructures often is carried out without taking into account the possibility of encountering subsurface cavities, and the corresponding danger these might pose. In addition, loss of memory of man-made cavities under the historic part of many towns adds further problems. Evaluation of the stability of rock masses in underground setting is not an easy matter, since it requires, in addition to the geological and engineering background, speleological skills and techniques in order to explore and survey the cavities, identify the type of failures occurring therein, and collect the data necessary for the implementation of specific numerical analyses. In this paper we present an approach involving cavers, geologists and engineers to assess the rock mass stability in natural and man-made caves, aimed at determining the control of rock failures in the formation of sinkholes. The methodology is described through the application to a natural karst cave and an anthropogenic cavity in Apulia, SE Italy. In both cases, following a detailed speleological survey which is specifically addressed to define the complete cave topography, the geo-mechanical characterization of the carbonate rock mass was carried out, and the data so obtained were used to evaluate the rock mass stability by means of numerical codes.

Natural or man-made underground caves potentially represent a serious hazard to the built-up areas. Urban development and construction of infrastructures is generally carried out without taking into account the possibility of interacting with subsurface cavities, and the corresponding hazard these might pose. In addition, loss of memory of man-made cavities under the historic part of many towns adds further problems. This is especially true for countries with a long history, such as Italy, where during the centuries a large number of artificial cavities have been excavated underground for different purposes. Assessment of the stability of rock masses in these settings is not an easy matter, since it requires, in addition to the geological and engineering background, speleological skills and techniques in order to explore and survey the cavities, identify the type of failures occurring therein, and collect the data necessary for the implementation of specific numerical analyses, thes...

It has been said that Palermo is short of available water. However, nothing could be more wrong. Well-documented Arab sources and narrative chronicles reported an abundance of groundwater resources in Palermo Plain since the Middle Ages. The scarcity of sources and surface water in the Palermo Plain, compared to the groundwater abundance, led the inhabitants to use groundwater both for irrigation and domestic usage through a complex and sustainable hydraulic system. Vertical and horizontal (qanāts) wells, conveyed water towards gardens and public fountains making the Arabic Bal’harm (Palermo) a flourishing town. When visitors walk through the streets of Palermo’s historical center, among Arab ruins and Baroque architecture, they hardly imagine that there is a wide and varied cultural heritage of underground cavities hidden in the basements where water flows in intricate networks fed from a numerous springs. Only in recent years was a part of this system brought to light. Moreover, t...

The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Cover Illustration: Porte di Pinerolo, north western Italy. Bridge located on Chisone river after the flood event occurred on October 2000. The photo shows the effects of extreme hydrological events on anthropic areas and infrastructures. Photo: Giorgio Lollino.

Sinkholes of both natural or anthropogenic origin are widespread phenomena in Italy, and locally constitute the main hazard. Notwithstanding the potential threat they represent to the built-up environment, sinkholes are rarely considered in the assessment of the geological hazards, and are generally underrated when compared to other hazards such as floods and landslides. Using a variety of information sources we have recently compiled a chronological catalogue of about 700 events that occurred in Italy. Mandatory for including a sinkhole in the catalogue is the knowledge of the date of occurrence. This is considered to be complete when hour/day/month/year of the event are all available, which corresponds to high accuracy of the record. When the information about time of occurrence is more limited (for instance, comprising only month and year, or a few generic information), the accuracy is considered of progressively lower degree (medium, medium-low or low). The documented sinkholes in the catalogue cover a time span from 276 B.C. to the present day. For any event the location (precise or approximate) is also included, ranked in different levels of certainty, according to the information provided by the sources or derived from our direct surveys. More than 50 % of the sinkholes in the catalogue are related to man-made cavities, excavated in different rock types, including limestones, calcarenites, and volcanic rocks. This is due to the complex history of the country, and the many phases of underground constructions that had occurred during the different epochs, with a variety of purposes (working places, rupestrian settlements, hydraulic works, quarries, worship sites, etc.). Location of these cavities often got lost in time, so that they were later on included in the expansion of newly developed towns, thus increasing the related risk. Natural sinkholes, on the other hand, are generally located in areas where soluble rocks (carbonates, evaporites) crop out, or where alluvial sediments are present; they definitely have a lower impact on the built-up environment, mostly affecting rural areas. Trigger of the sinkholes can be due to rainfall or seismic events, or to man-made works (realization and/or maintenance of pipelines, quarrying activities, etc.). Further, other important features of sinkholes are shown in the catalogue, covering morphometric characters (width and depth), lithologies involved, and occurrence as first collapse or as a re-activation of a former sinkhole. The regions with the highest number of documented sinkholes are: Campania (246), Sicily (117), Latium (107) and Apulia (88). Only two Italian regions (Molise and Valle d'Aosta) so far are not present in the catalogue with any documented sinkhole. Sinkholes have repeatedly caused in Italy heavy damage to the society. Water supply systems, sewer systems, roads and other communication routes were often damaged; in addition, damage and/or collapse of buildings, with the deriving casualties, had also to be registered in several circumstances. In the time span covered by the catalogue, casualties (which include deaths, missing persons, and injured people) are reported in 3.5 % of the events, whilst damage are documented in 32.6 % of the cases. The numbers above are underestimated, because most of the sources typically provide generic information, that often simply refer to the occurrence of an unspecified number of deaths and injured people (especially as regards the oldest reports). This, together with the ancient date of many events, is at the origin of the difficulty in precisely quantifying the intensity of the sinkholes, in terms of their effects on the society. Most of the damage was registered in central-southern Italy, and in particular in the aforementioned regions. This is partly due to the geological setting of these territories, and to availability of specific studies on sinkholes carried out in these regions (especially in the towns of Palermo, Naples and Rome) as well. The documented damage are described in this work, subdivided in different categories, according to the type of damage, number of casualties, geographic distribution, recurrence time of the sinkhole events in the different regions. Eventually, some preliminary considerations on the quality of the used sources is also provided.

Within the PanGeo project that aims at Enabling Access to Geological Information in Support to GMES (now Copernicus) services, the Geological Survey of Italy, together with the Urban Planning Department of Roma Capitale, have elaborated a geohazard map that integrates PSInSAR data with geological and geothematic data. The main objective of this service is to monitor the existing natural hazards and the potential ground instability zones within the Roma territorial municipality aimed at identifying risks in relation to urban planning.

RIASSUNTO-I sinkholes antropogenici nel territorio di Roma Capitale sono strettamente connessi alla rete di cavità sotterranee prodotta dalle attività umane (reti idrauliche, cave, catacombe etc.) che si sono svolte in più di duemila anni di storia della città. La presenza di tali cavità sotterranee produce il collasso degli strati più superficiali del terreno, a causa di crolli delle volte, con la formazione di voragini in superficie. Ulteriore causa della formazione di voragini è dovuta a guasti, perdite e alla disfunzione in genere della rete idraulica dei sottoservizi. Negli ultimi dieci anni si è assistiti all'incremento del fenomeno che ha determinato un rischio sempre maggiore per la popolazione e per le infrastrutture con danni alle strade e ai sottoservizi stessi (rete idraulica, rete elettrica, del gas, dei telefoni etc.). Bisogna tener conto, inoltre, per la città di Roma, che il fenomeno costituisce un problema per gli eventuali danni al patrimonio archeologico e per la preservazione dello stesso. In questo scenario la determinazione del rischio indotto dal verificarsi di un sinkhole è davvero difficoltoso, ma il concetto di rischio può essere sostituito più facilmente con la suscettibilità, calcolata come la probabilità che un evento di sprofondamento si verifichi in un determinato spazio, con determinate caratteristiche geologiche-morfologiche al contorno, in un tempo infinito. In questo modo può essere realizzata una carta di suscettibilità ai sinkholes antropogenici per il territorio di Roma Capitale. Essa può essere ottenuta considerando i fattori geologici, morfologici, idrogeologici predisponenti e valutando le caratteristiche dell'area in oggetto. Possono essere realizzati tre livelli nella metodologia: i) il primo livello prevede la possibilità di sprofondamento in un area a grande scala; ii) il secondo livello può estrapolare il modello in un'area con le medesime caratteristiche; iii) il terzo livello consiste nella valutazione spazio-temporale dell'evoluzione del fenomeno per una data area. Nel presente lavoro sono stati censiti più di 2000 sinkholes antropogenici ubicati nel territorio di Roma (dal 1875 al 2012) ed è stata proposta una metodologia per la realizzazione di un modello di suscettibilità basato sulla probabilità che l'evento di sprofondamento si verifichi indipendentemente dal tempo, mediante un sistema geo-statistico usando la regressione logistica (LR). PAROLE CHIAVE: Sinkholes antropogenici, carta di suscettibilità, cavità sotterranee ABSTRACT-Anthropogenic sinkholes in the urban area of Rome are mainly linked to the presence of a dense network of underground cavities, such as tunnels produced by historical mining activities, as well as drainage tunnels and catacombs linked to a history of more than two thousand years. 2011) The presence of these cavities may easily trigger the collapse of the shallow or deeper layers from ground level. Subordinate causes are associated to the loose of soil below the road surface linked to runoff phenomena concurrently with intense rainfall.

Abstract: It has been said that Palermo is short of available water. However, nothing could be more wrong. Well-documented Arab sources and narrative chronicles reported an abundance of groundwater resources in Palermo Plain since the Middle Ages. The scarcity of sources and surface water in the Palermo Plain, compared to the groundwater abundance, led the inhabitants to use groundwater both for irrigation and domestic usage through a complex and sustainable hydraulic system. Vertical and horizontal (qan􏰀ts) wells, conveyed water towards gardens and public fountains making the Arabic Bal’harm (Palermo) a flourishing town. When visitors walk through the streets of Palermo’s historical center, among Arab ruins and Baroque architecture, they hardly imagine that there is a wide and varied cultural heritage of underground cavities hidden in the basements where water flows in intricate networks fed from a numerous springs. Only in recent years was a part of this system brought to light. M...

Geospatial technology (that includes Remote Sensing and Geographical Information System GIS) has opened up opportunities for qualitative analyses of sinkholes distribution with multi thematic maps to define the relationship of GIS database. Kinta Valley have been deteriorating dramatically as a result of changes that had occurred in the past and continues due to the close relationship between the fast rate of lateral urbanization and extensive dimensional expansion of surface mining and quarrying activities, where sinkholes are the main crux of the geohazard in Kinta Valley. Geospatial information system for sinkholes had been established using pictorial, tabular and ancillary data to build a relational GIS database. The application is capable of analyzing an entire data set of sinkholes to create sinkholes distribution map. The objective of this paper is to highlight the value of Geospatial Information System as a tool to define sinkhole distribution and change detection for geohazard evaluation.