1,721,002 research outputs found
Building a database on geological hazards in karst: some considerations about certainty, accuracy and reliability in the collection of data
Full text linkSinkholes are definitely the most typical geohazard affecting karst territories. Even though typically their formation
is related to an underground cave, and the related subterranean drainage, sinkholes can also be observed on nonsoluble
deposits such as alluvial and/or colluvial materials. Further, the presence of cavities excavated by man
(for different purposes, and in different ages) may be at the origin of other phenomena of sinkholes, the so-called
anthropogenic sinkholes, that characterize many historical centres of built-up areas. In Italy, due to the long history
of the country, these latter, too, are of great importance, being those that typically involve human buildings and
infrastructures, and cause damage and losses to society.
As for any other geohazard, building a database through collection of information on the past events is a mandatory
step to start the analyses aimed at the evaluation of susceptibility, hazard, and risk. The Institute of Research for
the Hydrological Protection (IRPI) of the National Research Council of Italy (CNR) has been working in the last
years at the construction of a specific chronological database on sinkholes in the whole country. In the database,
the natural and anthropogenic sinkholes are treated in two different subsets, given the strong differences existing
as regards both the causal and triggering factors, and the stabilization works as well.
A particular care was given in the database to the precise site and date of occurrence of the events, as crucial
information for assessing, respectively, the susceptibility and the hazard related to the particular phenomenon
under study. As a requirement to be included in the database, a temporal reference of the sinkhole occurrence must
be therefore known.
Certainty in the geographical position of the event is a fundamental information to correctly locate the sinkhole,
and to develop geological and morphological considerations aimed at performing a susceptibility analysis. This
factor does not have to be disregarded since, especially for the most ancient events, the data from the sources
may be not of high precision for a correct positioning of the sinkhole site. As a consequence, each sinkhole in the
database was ranked according to the degree of certainty in the location, subdivided into three different levels.
Accuracy of the date of occurrence of the sinkhole was then evaluated, and the highest accuracy was assigned when
all the information required (hour, day, month and year of occurrence) were available. The temporal reference is of
crucial importance in the IRPI database, since the final goal of the research project is the definition of the sinkhole
hazard in Italy. In order to reach such goal, given the definition of hazard, the time of occurrence, and the most
likely return time of the events have to be assessed.
Overall, the aforementioned elements of the database allow to make some considerations about the reliability
of the information presented, their precision, and to give the correct weight to the outcomes deriving from its
analyses. Such issues are discussed in the present contribution, as crucial elements that need to be clearly defined
in a scientifically-sound database. The database has reached so far about 900 events (31% natural sinkholes and
48% anthropogenic sinkholes, whilst 21% of sinkholes have an uncertain origin). It is continuously updated, and
represents a good starting point for analysis of the sinkhole hazard at the national scale, aimed at increasing the
level of attention by scientists, practitioners and authorities on this subtle hazard
Mapping surface features produced by an active landslide
Full text linkA large landslide reactivated on December 2013, at Montescaglioso, southern Italy, after 56 hours of rainfall. The landslide disrupted over 500 m of a freeway, involved a few warehouses, a supermarket, and private homes. After the event, it has been performed field surveys, aided by visual analysis of terrestrial and helicopter photographs, to compile a map of the surface deformations. The geomorphological features mapped included single fractures, sets of fractures, tension cracks, trenches, and pressure ridges. In this paper we present the methodology used, the map obtained through the intensive field work, and discuss the main surface features produced by the landslid
A Chronological Database about Natural and Anthropogenic Sinkholes in Italy
Full text linkSinkholes are a widespread geological hazard, typical of karst lands, where they generally
originate as collapse features related to presence of underground voids. Nevertheless, other types of
sinkholes can be formed through solution, suffusion and sagging processes. Sinkholes can also be
originated in relation to artificial cavities, excavated by man in past times. In Italy, sinkholes interest
large sectors of the country, given the very long history of Italy with an intense utilization of the
underground. They cause serious damage to infrastructures, economic activities, and human health
every year. We present a catalogue on natural and anthropogenic sinkholes in Italy, as the first step
toward evaluation of the sinkhole hazard. After introducing sinkholes, which is definitely a highly
underrated type of disaster in Italy, we point out their occurrence in the country. We illustrate the
methodology used to build the database, with particular focus on accuracy and reliability of the data.
Collecting information from different types of sources, a catalogue of some 1190 sinkhole events is
built. Database structure and data analysis are then illustrated. Eventually, we draw some conclusions
on the likely uses of our work by providing recommendations for environmental management on
this very delicate issue
Slope movements shaping the landscape in the Daunia Apennines (Southern Italy), and their effects on the built-up environment
No full textThe southern Apennines of Italy are characterized for wide sectors by outcropping of clay materials, highly prone
to slope movements. This determines a high susceptibility to landslides, which, combined to expansion of the
urban areas during the second half of the last century, bring to high vulnerability, too. In Daunia, the hill-tomountain
sector of Apulia, a transition area between the Apulian plain and the Apenninic Chain, slope
movements represent the main agent modelling the landscape. They are mostly in a dormant state of activity,
which nevertheless can change to active, generally due to rainfall or seismic triggers. A further triggering factor,
which is quite often under estimated, is represented by the human action. Lack in the identification of ancient
slope movements, and planning of engineering works and construction in landslide-prone areas, has often
resulted in partial or total re-activations of ancient slope movements. In the present article, through analysis of an
historical database about landslides in Daunia, we intend to investigate the control exerted by gravity-related
phenomena on the landscape, the interaction between slope movements and human activities, and the effects
produced by landslides on the anthropogenic environment. The issue of rainfall-triggered slope movements is
also dealt with, with a first attempt in identifying pluviometric thresholds for the study area
A subtle and hidden natural hazard: origin, development and evolution of sinkholes
No full textAmong the many geological hazards affecting the Italian territory (earthquakes, volcanic eruptions, slope
movements, floods, wildfires, etc.), and causing severe losses and casualties, sinkholes are rarely considered in
hazard and risk analysis. Nevertheless, their occurrence, with the consequent negative effects on the built-up
environment and human infrastructures, affect large parts of Italy, covering the whole country with a variety of
typologies. Sinkholes mostly occur in karst areas, where soluble rocks such as carbonates and evaporites crop
out or are present at low depth (De Waele et al., 2011). Development of sinkholes, however, may also be
registered in alluvial plains, involving thick sequences of alluvial and colluvial deposits (Fig. 1).
Recently, an effort was produced by the Institute of Research for the Hydrogeological Protection with the
National Research Council of Italy (CNR-IRPI) to build a chronological catalogue on sinkhole phenomena in
Italy, addresses toward the evaluation of the sinkhole hazard (Parise & Vennari, 2013; Parise et al., 2013). The
chronological catalogue of sinkholes is specifically focused on the time of occurrence of the events, that is
considered a crucial element for the definition of the sinkhole hazard. Even though the catalogue takes into
account both natural and anthropogenic sinkholes (these latter being those events related to presence of manmade
underground caves), given the topic of this conference, the present contribution will deal exclusively with
natural sinkholes. Knowledge of the dates of occurrence of sinkholes represents the necessary element for
definition of the hazard; at the same time, discriminating between sinkholes related to presence of natural or
man-made caves may determine very different scenarios to be faced, in terms of civil protection actions.
A sinkhole at the surface appears as punctual (site-located), and typically of limited dimensions. This, however,
does not mean that the affected area is limited to that specific point, since underground the caves responsible for
the event may potentially develop for a much wider extension. With respect to natural sinkholes, these typically
are found in areas with soluble rocks affected by karst processes, or alluvial sediments in peculiar geological
situations. Thus, the zonation of the sinkhole-prone areas may be done for natural sinkholes based solely upon
geology as a first approximation
A chronological catalogue of sinkholes in Italy: the first step toward a real evaluation of the sinkhole hazard
No full textAmong the many different types of geological hazards affecting the Italian territory, sinkholes have often been underestimated (if not neglected entirely), and only in some sectors of the country have they been effectively considered in hazard and risk analysis. Nevertheless, sinkholes affect large parts of Italy, covering the whole territory with a variety of typologies, and exhibit both natural and anthropogenic origin. The latter clearly originate from the long history of Italy, with the complex historical vicissitudes that have characterized this territory, during which different types of artificial cavities have been realized underground for different purposes in different epochs. Over time, many of these cavities have been abandoned, and the consequent loss of memory resulted in their inclusion in newly developed parts of towns, thus creating a serious risk to the built-up environment above.
Starting from these considerations, an archival research was started to collect information about the occurrence of sinkholes in Italy, with particular attention to their precise site and date of occurrence, in order to make an effort in assessing, respectively, the susceptibility and the hazard related to the particular phenomenon under study. As concerns date of occurrence, the accuracy of the information is provided (depending upon the amount of available data), with the highest quality when hour, day, month and year of occurrence are indicated, and a decrease in quality when one or more of these data are lacking. In order to be included in the database, at least some kind of temporal reference (even if general) of the sinkhole has to be known
An historical database on alluvial events in torrential catchments of Campania region (southern Italy)
No full textAlluvial events in Italy are a constant and continuous problem due to the peculiar orographic and climatic setting of the territory. Even though less frequent than in the Alps, debris-flows and floods greatly contributed also along the Southern Apennines to build alluvial fans, a widespread geomorphic unit located at the catchment mouth. These areas have been frequently chosen as sites for the urban development, as they were considered safer than the valleys, for the lower probability of being affected by floods. Due to the orographic position, the heavy rainfall events characterizing the study area can lead to flash floods with large debris loads. Such phenomena may be extremely risky for the population, and cause heavy damages. Starting from the consideration that past events can provide information on future events, we compiled a database on alluvial events in torrential catchments of Campania region, a highly prone area to such phenomena. By consulting different types of information sources we collected about 500 events. The database is being constantly updated, and contains temporal and spatial information for each event, since availability of these data is considered a mandatory step in order to perform a correct hazard and risk analysis
Sinkhole clusters after heavy rainstorms
No full textSinkholes are the most common geological hazard in karst terrains. Generally triggered by rainstorms or by changes in the hydrological/hydrogeological regime, they display a wide range of morphologies and sizes. Typically, the main difficulty in evaluating the sinkhole hazard is represented by the collection of reliable data about time of occurrence of the events, which is a mandatory requirement for the estimation of the hazard. In this paper, we document a dozen sinkholes triggered by a heavy rainstorm that occurred during the first week of September 2014 in the Gargano Promontory of Apulia (southeastern Italy). Following a description of the rainstorm, two clusters of sinkholes are described, starting with the identification of the sinkhole type and of the main morphometric characteristics. Even though it is very likely that the documented sinkholes are only a fraction of those caused by the September 2014 rainstorm, this documentation provides insights for the collection of important sinkhole data produced by a specific, triggering storm
Typology, origin and distribution of anthropogenic sinkholes in Italy
No full textItaly is among the countries in the world hosting the highest number of cultural and historical heritage sites, both at the surface and underground. The widespread presence of artificial cavities, excavated by man all over the country in different time periods and for a variety of purposes, is a primary reason for the large number of subterranean sites. It is not a case that in Italy the studies and research about artificial cavities have played a prominent role on the international scene, leading in 2012 the UIS (International Union of Speleology) Commission on Artificial Cavities to adopt the classification originally established in Italy. Growing urban expansion in Italy, which began after World War II and had a boom during the 1960s and 1970s, has resulted, in the later decades up to today, in loss of memory of many of the cavities located below the urban areas. This is one of the factors at the origin of the high number of sinkholes which have characterized and controlled the development of many important cities such as Rome, Naples and Palermo. These cities, however, are only the tip of an iceberg, since anthropogenic sinkholes are present in practically all Italian regions, and repeatedly have caused severe damage to society, and locally casualties. In this contribution, starting from the analysis of a chronological database of sinkholes in the Italian territory, we present our considerations about the different types of artificial cavities more prone to instabilities and sinkholes, the main factors controlling
the underground failures, and their distribution in the different Italian regions. The most significant case studies will be used to illustrate the above features, and to present the sinkhole hazard within the general framework of geological hazards in Italy
Sinkholes inclusion in a geodatabase about geo-hydrological hazards in Apulia, southern Italy
Full text linkThekarstnatureoflargesectorsofApulia,combinedwiththehighdiffusionofdifferenttypesofartificialcavities, make sinkholes among the most widespread geo-hydrological hazards in the region. They have caused several damage to infrastructures, building and population. Sinkholes represent a widespread problem in Apulia, and therefore they must necessarily be considered in studies concerning the regional geo-hydrological hazards and the related risks. With this aim we included sinkholes in a regional geodatabase concerning floods and landslides in Apulia, as a fundamental step for the susceptibility and hazard study of sinkhole occurrence on the specific territory. At these aims, it is necessary that the database is rigorously built, based on reliable information and data, including all those elements necessary for the subsequent analysis. Here we present a geodatabase about geo-hydrological hazards, developed by the geomorphology group at the Institute of Research for the Geo-Hydrological Protection of the National Research Council of Italy (IRPI-CNR), now modified to take into account the geomorphological characteristics of Apulia, namely the sinkhole phenomena. A sinkhole is considered as a “phenomenon”, belongs to an “event” that represent the ensemble of the phenomena (landslides, floods, sinkholes) caused by a “trigger” (of meteorological, seismic, or anthropogenic origin). In the database are included all the sinkholes for which the connection with an underground cavity, either of natural or anthropogenic origin, is certain. In addition, the information on occurrence time of the sinkhole, and knowledge of its location, are fundamental. The geodatabase allows to collect information about different types of geo-hazard (landslide, flood, sinkhole), to record with different geometry (point, line, polygon) both the location of the phenomena and of the damaged objects/mitigation works, to report data in format compliant with the EU Flood Directive (2010), even in the specific format required by the Department of the Italian Civil Protection
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