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Moving geosites: how landslides can become focal points in Geoparks

DOMENICO CALCATERRA1*, DOMENICO GUIDA2 , PAOLO BUDETTA3, PANTALEONE DE VITA1, DIEGO DI MARTIRE1 AND ANIELLO ALOIA4

1. Department of Earth Sciences, Environment and Resources, Federico II Naples University, Corresponding author: [email protected] 2. Department of Civil Engineering, University, Italy 3. Department of Civil, Arch. and Env. Engineering, Federico II Naples University , Italy 4. National Park of , Vallo Diano and - Geopark, Italy

Abstract: - Landslides are both landforms and geomorphic processes contributing to the long-term landscape evolution and one of the deadliest sources of natural hazard which endanger lives, property and activities. Many people in the world have experienced historical coexistence with landslides and related hazard, adapting settlement location and typology, land use and best practices. At large, local cultural identity is strongly influenced by this adaptation, while, in a few cases, landslides are expressions of both geodiversity and cultural identity. In these cases, it seems appropriate to refer to “moving geosites”, where academic researches supported by geoparks provide insights to educational system and dissemination to the public administrations, both as geodiversity functioning and effective approach to landslide risk reduction by raising public awareness.

Key-Words: Landslide, Geosite, Moving Geosite, Geodiversity, European Geopark Network, Cilento--Alburni Geopark

1 Introduction The territory of Cilento and Vallo di Diano Geopark A recent study carried out by ISPRA, the Italian originally fell under the jurisdiction of two RBAs Agency for Environmental Protection and Research (RBA Interregionale del Fiume Sele and RBA (IFFI Project - Italian Landslide Inventory; [1]) Regionale “Sinistra Sele”), which in 2012 have inventories more than 485.000 landslides in Italy, been unified, along with a third RBA, under a new distributed over all the twenty Italian regions. RBA named “Autorità di Bacino regionale Among them, region occupies a quite Campania Sud ed Interregionale per il bacino high position in this unenviable ranking, as regards idrografico del fiume Sele”. Both RBAs have landslide density, with 171 events/100 km2. In Italy, recently updated their HSPs; integrating the landslide risk and its mitigation have been respective landslide-inventory maps, Figure 1 has organically treated for the first time with the Law been created. Here, slightly less than 13.500 no. 183/1989. However, it was only after the huge landslides are represented, many of which never tragedy occurred at and in other four inventoried beforehand [2]. Campanian towns (160 death due fast-moving The Geopark’s landslides pertain to all the possible landslides) on May 5, 1998 that the above Law was types recognized by modern classification schemes. fully accomplished, especially as regards to the According to the Cruden & Varnes’ landslide implementation of the River Basin Authorities classification [3], rotational and translational slides (RBAs), public bodies responsible for the are the most common phenomena, followed by governance of the hydrographic basins. RBAs, complex movements; the latter, in turn, represent the widest ones, in terms of areal extent. Landslides among their duties, have to carry out the “Basin 2 Plan”, a comprehensive programme of land cover about 300 km of the Geopark territory and management projects, which include the Hydro- are present in 78 out of the 82 municipalities geomorphological Setting Plan (HSP) aimed at belonging to the Geopark community. , identifying areas exposed to landslide and flood and are the municipalities where landslides affect more than 10 risk, and at mitigating it within levels consistent 2 with the existing land use, so as to safeguard human km of territory. Most of the inventoried landslides lives and reduce as much as possible the damage to show an average intensity, which can be expressed material properties. as a maximum expected velocity from slow to

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moderate (from 5 × 10-5 to 5 × 10-1 mm/s). different geo-materials). This is the main reason Consequently, according to the existing Italian laws why, as regards landslides, typological and regulations, the Geopark territory is prevailingly classifications, which subdivide phenomena into affected by average landslide risk. repeating patterns (“types”) characterized by some During the 12th EGN 2013 Conference, organized descriptors, got success with time. According to by the Cilento, Vallo Diano and Alburni Geopark [9], any landslide can be classified and described by (CVDA Geopark), the following topic was two nouns: the first describes the material and the discussed: “Geoparks, as innovative approaches to second describes the type of movement (e.g. rock raise public awareness in natural geo-hazards, fall, debris flow). Additional aspects of a landslide climate change and sustainable use of the need to be defined, especially when its hazard is resources”. In this context, according to the mission considered. It is therefore convenient to indicate for on “raising public awareness” about landslide a given landslide its “magnitude” or “intensity”, as hazard and risk, the aim of the CVDA Geopark is to “a set of spatially distributed parameters describing convert some representative landslide areas into the destructiveness of a landslide”[10]. Despite publicly accessible geosites. This action was such a straightforward definition, a univocal considered as an effective way to strengthen general quantitative definition of “landslide intensity” is not awareness and knowledge of all the possible available at present, since it can be quantitatively relevant geological assets, singular assessed only using a variety of parameters, such as geomorphological evolution and historical aspected or actual maximum velocity, total cohabitation experience about landslides [4]. displacement, volume of the involved mass, depth Previous studies have addressed many efforts to of the moving mass, etc.. Some of the above assess landslide risk affecting geosites for parameters, however, represent key-factors in the geotourism accessibility (e.g. [5]), while minor landslide hazard evaluation. Among them, the attention was given in the literature as to consider a movement velocity is unanimously considered as an landslide as a geosite in itself (e.g. [6]). element which can be easily linked to human This paper discusses on conceptual premises, response, since the destructive potential of a scientific definitions and institutional formalization landslide depends on its velocity [9] and [10]. of a new concept in geodiversity management: Landslides from extremely rapid to very rapid, “moving geosite”. As to make the concept more exhibiting velocities of the order of 5 m/s, are perceptible, a few cases of “moving geosites” are relevant in terms of danger to human life because described. corresponds to the speed of a person running and could be called “catastrophic velocity”. Slower movements (slow, very slow, extremely slow) usually cause only material damage, being 2 From Landslide to Moving Geosite characterized by rate of movements lower than 5 × The concept of landslide was effectively stated by 10-3 mm/s. In these cases, living with landslides is Varnes [7] as “a downward and outward movement possible, especially when the phenomena are under of slope forming materials composed of natural control, by means of monitoring instruments (e.g.: rock, soils, artificial fills, or combinations of these inclinometers, piezometers, GPS, remote sensing). materials”. The same author simplified its previous Many landslides show an intermittent behaviour definition, by reducing it to “a downward and during their long-term evolution, following the first- outward movement of slope forming materials under time activation. Long periods of very slow bulk the influence of gravity”. Cruden [8] further deformations are interrupted by relatively short simplified such definition, stating that a landslide term, fast, partial or global re-activations. Return denotes “the movement of a mass of rock, debris or times of these re-activations can be very variable, earth down a slope” from decadal to centennial or even millennial. When As it occurs whenever a complex issue must be reactivations span from decadal to centennial, simplified, to classify landslides has been one of the historical memory promotes the human cohabitation main interests for researchers and professionals. and coexistence with landslides. On the contrary, in Due to their intrinsic complexity, landslides cannot case of very long return times, people could not rely be easily classified following a rigid taxonomic on experience and tend to forget the past dangerous system, as in the case of plants or animals, due to phenomena and the previously affected areas. In this several difficulties (e.g. events not perfectly case, it may be appropriate to associate usual repeatable; occurrence of different causes, monitoring activities with communication and movements and morphology; involvement of public awareness focused on the most representative

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examples of reactivable landslides. The latter is, in Severino di Centola, S. Giovanni a Piro, Gorga- general, one of the missions of the European and and are only a few examples of Middle Global Geopark Network and, in particular, one of Age villages, historically conditioned by distinctive the main goals of the CVDA Geopark, by using geological settings and landslide evolution. distinctive and representative landslides as “moving In the following, location, geological and geosites”. geomorphological sketches are presented, along According to the commonly accepted definition a with main geodiversity features of a few of the geosite can be defined as “a site location area or above cited moving geosites (Fig.1). territory in which it is possible to identify a geological or geomorphological interest for conservation” [11]. Reynard [12] added that an active geosite allows the visualization of geological 4 and geomorphological processes in action, whereas passive geosites testify past processes. 3.1 Here, we tentatively introduce the concept of “moving geosite”, as an active geosite which changes its morphology and spatial position due to representative geological constraints and singular, long-term, geomorphological, gravity-driven slope processes, today in action and/or clearly observable on the ground and/or as effect on man-made structures. These processes, however, are not such 3.2 as to endanger human lives but can threaten human 3.3 property, thus allowing a geosite to maintain all its 3.4 intrinsic value and to be publicly accessible. Accordingly, natural geomorphological phenomena such as slow-moving, monitored or historically documented landslides or retreating coastal cliffs can be classified as a moving geosite. Figure 1. Landslide and Moving Geosite map of the Following [13], if the value of a geosite may be Geopark (mod. from [2]). Legend: 1) Rockfalls/topple; 2) Diffused shallow slow deformation; 3) Diffused complex assessed on the basis of four groups of criteria: landslides; 4) Slow earth flow; 5) Rapid debris flow; 6) scientific, cultural/historical, aesthetic and/or Complex landslide; 7) Rockslide; 8) Deep-seated gravitational social/economic, the proposed “moving geosite” can slope deformation; 9) Lateral spread; 10) be well accepted as a new concept in geodiversity . Rotational/translational slide.

3.1 Caporra-Laurelli- This proposed “moving geosite”, is located along 3. Prototypal Moving Geosite the south-eastern mountain slope of Mt. Centaurino In the following, relevant cases of “complementary (Fig. 2) and is geologically connected to the Main and focal moving geosites” are presented, by using Geosite n. 113 “Ophiolithic Olistolites of an adapted meaning of “complementary and focal Centaurino” of the “List of the Geosites”, Appendix geosites” proposed by the Candidature Dossier by “A” in [14]. Along the mountain slope sandstone- the Cilento Geopark. conglomerate successions crop out, and they are A “complementary moving geosite” means a laying in unconformity above the paleo- location where the international value in geo- depositional units consisting in marly-clayey heritage is strictly connected to archaeological successions. The first are related to the Cilento vestiges, as examples of risk, resources and climate Group (one of the most distinctive geological unit of change conditioning in past human land occupation. the CVDA Geopark) and the lasts to the Ligurian A “focal moving geosite” means a location where, Units both referred to Thethian domains, over- in addition to previous characters, forms of geosite thrusted on the Bifurto- formations, fruition and management are already in use, also in referred to the Alburni--Pollino Unit [15]. risk mitigation and resource protection. The Caporra landslide develops along the contact Among others, the cases of Velia-, Petrosia- between the above mentioned units, affecting both , Caporra-Caselle, Civitella-Moio are the arenaceous successions overlying the pelitic relevant examples of Italic, Greek and Roman ones. settlements, conditioned by geological constraints.

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easily accessible via the public road Caporra from Caselle in Pittari village, famous in the Geopark for its eno-gastronomy, where you can taste local products and enjoy the picnic areas closed to low- mineralized spring waters.

3.2 Moio della Civitella can be considered as a “moving town”, due to a number of dormant/active landslides which affect large portions of the urban area. The origin of Moio dates back to VI÷IV century BC, and some archaeological on the hilltop named Civitella remains on testify to these ancient periods. Nowadays, it is a small town of some 1700 inhabitants and it is composed of two urban centres, Moio and Pellare. From a geological point of view, the prevailing outcropping complex is represented

Fig. 2 – The Caporra moving geosite, modified from by the Crete Nere-Saraceno Frm’s. [15], mainly South Campania RBA Inventory map. Legend: 1: made up of argillites with intercalated carbonate and Rockfall/Topple; 2: Roto-Traslation Slide; 3: Debris flow; 4: silicoclastic arenites, often weathered at the outcrop. Rapid Earth flow; 5: Earth flow; 6: Slow flow; 7. Complex A Quaternary cover given by heterogeneous debris landslide; 8: Deep Seated Deformation; 9: Soil creep; 10: Areas in a silty-clayey matrix closes the succession. affected by diffuse rockfall/topple; 11: Diffuse landslides; 12: Mass creep; 12: Ridge; Moving geosite boundary. As a consequence, several tens of mass-movements have been inventoried over the territory of Moio It can be classified as rotational multiple slides, with della Civitella, where complex landslides and sliding planes located at a depth of more than 10 m, rotational slides evolving to translational slides are evolving downslope as slow earth- and rapid debris the prevailing types (Fig. 3). flow. The landslide can be considered as “moving geosite” due to its representativeness of an uniform long-term trend observed in the widespread landslide evolution involving: i) mid-slope rotational slide as original triggering mechanism in the erosional knickpoint; ii) retrogressive landsliding toward watershed; iii) progressive disarticulation and remoulding of landsliding materials until their flowing phase. In such a long- term evolution, the landslide system alternates slow movements and slight changes in morphology over a time scale of decades with short monthly acceleration of the displacements and strong topographic modifications, as surface expression toward flow-like event. A progressive shortening of the reactivation phases causes the collapse of the landslide system and the emptying of the landslide basin. One of this past collapsing event destroyed the Italic and Roman settlements of Laurelli, Fig. 3 – The Moio della Civitella moving geosite, currently managed as local archaeological site. The modified from South Campania RBA Inventory map. For moving geosite is suitable for scientific and legend, see Fig. 2. educational field applications of geomorphological survey techniques, mid-term morpho-evolutive and The role played by landslides in the morpho- short-term landslide activity mapping, dendro- evolution of the area is well demonstrated by the chrological analysis, topographic surveys and outcomes of the IFFI project and South Campania advanced geotechnical controls. Finally, the site is RBA [1]. Many of these landslides are dormant,

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while partial reactivations are common during the where the main roads to the Policastro Gulf and rainy seasons. coast are located. The Medieval hamlet has At Moio della Civitella, a multidisciplinary study is been abandoned since the end of 19th century. The ongoing [17], [18]), based upon the integration of historical nucleus of San Severino and its most remote sensing-based methodologies and recent part, built downvalley, are both located on the conventional ground-based techniques. Inclinometer northern slope of Mt. Bulgheria, made up of soundings and topographic network constituted by carbonate rocks belonging to the Campanian- over 100 benchmarks are available, along with some Lucanian-Calabrian Platform, whose age range from piezometers, and the related data are being collected Upper Triassic to Eocene [26]. In the area occupied since 2007. Moreover, in the same years a GPS by the Medieval hamlet thinly bedded, NNW network was installed, whose functioning has been, dipping calcilutites and marly limestones crop out, however, temporarily discontinued due to technical along with fine-grained marly (“scaglia rossa”-like) and financial problems. The ground-based intercalations (Fig. 4). monitoring has been supplemented with data coming from remote sensing techniques, represented by the processing of SAR images in the time-span 1992-2010. These data have been further validated through a critical inter-comparison with two detailed field surveys, carried out in November 2007 and December 2013 respectively. aimed at evaluating distribution and degree of the landslide damage to buildings according to the a classification already applied to several unstable towns in southern Italy ([19], [20], [21]. Thanks to the PS-technique, 345 permanent scatterers were identified [20], which allowed to detect average values of velocity up to 16.2 mm/year in the time span 1992÷2001, to be related to intermittently moving landslides affect various sectors of the urban settlements of Moio and Pellare. Di Martire et al. [22], adopting the Coherent Pixels Technique [23] recognized average displacement rates in the order of 5-10 mm/year, Fig. 4: Map of the S. Severino di Centola moving geosite. along a E-W direction, coherent with the ground Legend: 1 Recent sandy–clayey deposits, 2 Bifurto formation, 3 data. Evidence of almost continuous surface calcilutites and marly limestones, 4 rockfall detachment line, 5 displacements in the urban area were confirmed by rock slide, 6 detected boulders, 7 path segments with bouncing both the monitoring network and the landslide motion mode, 8 path segments with rolling motion mode. damage survey. As for the latter, the damage In this area, the sub-vertical slope (about 85°) is pattern already observed in 2007 revealed a crossed by several NW-SE and NE-SW oriented substantial worsening in 2013, especially in the faults, many of which showing low angles; the southern and eastern part of Pellare. Moving from whole carbonate rock mass is severely jointed, as a this previous knowledge, Moio dela Civitella can be consequence of its involvement in the last tectonic considered as a place of absolute interest as to stages, dated back to Upper Pliocene [24]. The demonstrate the possibility to coexist with active medium-lower part of the slope, showing an geological phenomena. elevation between 150 and 100 m a.s.l., is made up of thin beds of sandstones, intercalated with clayey marls. These lithotypes, showing a chaotic setting, 3.3 S. Severino di Centola are mantled by a weathered sandy-silty cover, a Due to several rockslides and falls affecting cliffs few metres thick. A normal fault, E-W oriented, is overhanging the Medieval hamlet and the State juxtaposed between the stratified calcilutites and Road “Mingardina”, the San Severino di Centola the underlying flysch deposits. Downslope, where site can be considered an interesting example of the new town of San Severino is located, slope Geosites exposed at high landslide risk. This angles become lower: here, debris and alluvial fortified hamlet had been built in that position as to deposits crop out, along with made-ground control the underlying valley of the Mingardo River,

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deposits. Along the slope sector where the flysch possible to map-delineate zones of high, medium deposits crop out, the former State Road no. 562 and low rock fall hazard. In the high and medium “Mingardina” runs with a very tortuous path, hazard zones, people are at risk of injury both characterized by quite high longitudinal gradients. inside and outside buildings. Damage to buildings The road is characterized by the following: (1) only should be expected, but not a rapid destruction as one single lane going in each direction without an long as the construction type has been adapted to adequate hard shoulder; (2) no ditches to retain any the present conditions. In the low hazard zone, fallen rocks, allowing the material to spill out onto people are at slight risk of injury. This zone is the road; and (3) a high degree of road curvature mainly an alerting domain. In Switzerland, these resulting in a small percentage of the decision sight maps are basic documents for elaboration and distance. The road is not wide enough in most improvement of Regional and Communal Master places to allow vehicles to overtake one another Plans for land use; planning, construction and (especially buses and trucks) or vehicles travelling transformation of buildings and infrastructures; in opposite directions meeting up. The study area is granting of subsidies for building and development, affected by falls and planar slides, which involve as well as for slope stabilization and protection the well stratified calcilutites. In the upper part of measures. In conclusion, this case-study allowed to the slope, the discontinuities’ attitude and the rock verify results furnished by new rockfall hazard and mass intense jointing favour the detachment of rock risk methods, in order to map-delineate areas volumes of variable size, which reach the road and affected by rockfall trajectories and to design the underlying urban area. Events of such kind rockfall protection systems. As the increasing occurred in 1980, 1992 and 2008, causing victims tourist number makes worse involuntary risk (1 in 1980), injured (in 2008) and road closures for conditions of appealing but arduous resorts affected several months. The triggering factor of the by active landslides, the San Severino geosite can December 15, 2008 landslide was represented by be considered as an interesting case-history in order the intense antecedent rainfall and the event can be to demonstrate that the fruition cannot leave out of classified as a planar failure occurred along the consideration the landslide hazard zoning and calcilutites’ bedding planes; the latter were crossed, mitigation of risk conditions. laterally and upslope, by high-angle, high- persistence joints and by sub-vertical joints, showing a direction parallel to the slope face. The 3.4 Gorga-Stio occurrence of two important joints, NW-SE Along the western slopes of the Mount Tempa oriented, contributed to subdivide the unstable Casalicchio (818 m a.s.l.), located at the upper mass in three parts, characterized by almost parallel northeastern limit of the River basin sliding directions. The detached volume has been watershed (Cilento and Vallo di Diano Geopark, evaluated as large as about 4.000 m3; the landslide Campania region, southern Italy), clear accumulation, made up of blocks up to 7 m3 and geomorphological evidences lead to recognize the more, prevailingly stopped at the foot of the rock existence of a large landslide which involves cliff. However, some blocks, bouncing and rolling completely the Gorga settlement (about 1000 along the medium-lower part of the slope, invaded inhabitants), belonging to the Stio Municipality. The the road, in some cases with a further downslope morphological setting of the area as well as damages movement, which, in turn, allowed the unstable suffered by buildings, especially during a partial mass to reach the slope base. For the studied slope reactivation occurred during the ‘50s of the last according to rockfall trajectories drawn by means century, indicate that the activity of the slope of impact marks and boulder stopping points, two gravitational phenomenon can be guessed as hazard scenarios have been proposed [25]. A first comprised between the relict stage, at the scale of scenario was drawn on the basis of the trend of iso- the whole slope, and the long-period dormant state, kinetic curves. This trend was established if considering the most mobile parts of the landslide interpolating energy values measured along several body. This phenomenon was firstly studied in a topographical sections. Furthermore, areas exposed preceding geological and engineering to 30% and 70% frequency of block transits and geomorphological analysis of the upper Alento endpoints were bounded. With reference to the River, which depicted a preliminary geological Swiss Federal Guidelines [26], another scenario model and fundamental geomorphological features was prepared on the basis of possible kinetic of the landslide. More recently, the updating of the energies due to rock falls with 100-year return geological knowledge [27], has given further periods. According to these approaches it is details and characterizations of geological units

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constituting the Gorga and Stio surroundings. main scarp are clearly distinguishable along the According to these results, the western slope of the slope, between 710 and 720 m a.s.l., by the analyses Mount Tempa Casalicchio, from the top (818 m of aerial photos and topographic anomalies, a.s.l.) down to the main valley of the Alento River although their morphological appearance indicates (430 m a.s.l.), is characterized by basinal and clearly a relict state of activity. This is also turbidite series with a composite stratigraphic and confirmed by the advanced weathering of bedrock structural setting, which can be simplified by the outcrops along the main scarp. Within the main identification of principal engineering geological body, a series of minor forms, such as depressions units, namely lithological complexes. The upper part and counterslopes testify a composite spatial and of the Mount Tempa Casalicchio is constituted of a temporal kinematic evolution of the landslide due to marly and calcareous lithological complex, differential minor reactivations which involved belonging to the Torrente Trenico unit (Upper lateral and frontal zones of the main landslide body. Eocene-Lower Miocene), which is superposed over In particular, one of these morphological signs is an argillaceous and calcarenitic lithological extended across the Gorga settlement being complex, including the Genesio unit (Eocene). presumably related to the recent reactivation While the first is characterized by an almost regular occurred in the ‘50s of the last century, which downslope-dipping bedding, the second lithological caused severe damages to building in the town. In complex shows stronger tectonic deformations due general, the relevant degree of dissection of the to polyphasic folding and shearing. Such landslide accumulation zone in its terminal part as lithological and structural features make the rock- well as the negligible deviation of the Alento River mass of the latter lithological complex with a lower path indicate a prolonged period of inactivity of this shear strength. The abovementioned units are mass movement. On the basis of the preliminary overlaid by a regularly bedded turbidite arenaceous- geological model of the landslide, which is pelitic complex, belonging to the Formation reconstructed by results of geological survey only of the Cilento Group [15], which is supposed to be (Fig. 5), the geological and structural predisposition in lateral contact by a normal fault (Fig. 5). to landslide occurrence can be recognized in the superposition of the marly and calcareous lithological complex over the argillaceous and calcarenitic one. This geometric and geo-mechanical conditions, along with the downslope dipping of bedding of the first member, led the triggering of the landslide with a complex style [37]. According to this evolutionary scenario, the landslide started as a rock slide and evolved in a rock-earth flow [3]. Further studies should be carried out to define in greater detail the geological model of the landslide, based also on borehole and geophysical data, in order to clarify the underground geometries and the Fig. 5: Engineering geological map of the Gorga moving possible involvement in the slope mass movement geosite. Legend: 1) Current alluvial deposits; 2) Landslide of a chaotic interval, which is often found at the deposits; 3) Arenaceous-pelitic lithological complex (Pollica base of the Cilento Group, as in the Caporra area Formation); 4) Marly and calcareous lithological complex (Torrente Trenico unit); 5) Argillaceous and calcarenitic (see par. 3.1. The Gorga landslide is of particular lithological complex (Genesio member); 6) Fault; 7) Bedding relevance in the Geopark because it represents a attitude; 8) Complexly folded and shearing deformation of special case of geohazard related to a long-term bedding; 9) Landslide main and secondary scarps; 10) dormant landslide, which is challenging to be Counterslope; 11) Depressed areas; 12) Roads; 13) Buildings. assessed due to the difficult determinable recurrence of reactivation and complex kinematic modelling. The morphological analysis of the unstable slope, For such scientific reasons as well as for historical carried out at 1:5,000 a scale, allowed to identify a value of the Gorga settlement, this area constitutes number of principal and minor landslide structures an emblematic example of “moving” geosite to be and to formulate hypotheses about the evolution of included among geosites of the Cilento Geopark, the phenomenon and its kinematics. with the scope to increase awareness about The landslide has an overall length measured along geological risks and their management. its median axis of about 1500 m and a height of 280 m (average slope angle of 11°). The remnants of the

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3.5 Pisciotta-Rizzico ortophotos in the period 1955-2006, and through a In the Rizzico locality, Pisciotta Municipality specific topographic monitoring carried out between (Cilento, Vallo di Diano and Alburni Geopark, September 2006 to March 2009 in the upper sector Campania region, southern Italy), a slow-moving of the landslide. An engineering-geological model slope mass movement is known since several of the landslide was reconstructed by means of decades ago to have repeatedly damaged the stratigraphic data derived by a campaign consisted provincial road SS 447 along a stretch with a length of boreholes, inclinometer monitoring as well as of about 600 m (Fig. 6). geological and geophysical surveys (Fig. 6). The analysis of aerial photographs demonstrated the existence of an early stage of deformation since 1943 that has expanded progressively in the following years. Besides of the main scarp and the landslide flanks, other significant longitudinal and transversal cracks as well as positive or negative morphologies were clearly observed and mapped during the following years. A progressive depletion of the upper part of the slope, a bulging of the landslide foot and a progressive enhancement of the morphological impact of the principal landslide structures were reconstructed. The quantitative kinematic analysis based on the Fig. 6 Aerial view of the Pisciotta Moving Geosite estimation of progressive displacements of the road (modified from Google Earth, 2004). (1955-2006) and on the topographic monitoring of optical targets allowed the assessment of ground Damages consisted in slow vertical and horizontal deformations for about 53 years (1955-2009), with a deformations of the roadway and of the retaining total maximum displacement of the road of about 55 walls as well as in slow opening of cracks in the m and an average velocity of about 1 m year-1. The road surface. Low velocities of displacement have kinematic analysis showed a progressive and allowed the continuous repairing of the road to constant deformation, with a little increase of maintain the vehicular traffic in a fairly safe velocity after 1994. Average velocity of about 0.4 condition. Since October 2013 the road SS 447 was cm day-1, maximum values up to 1.3 cm day-1, after definitively closed due to the excessive deterioration prolonged rainfalls, and minimum velocity of about of road conditions which has prevented a safe 0.1 cm day-1, at the end of the dry season, were vehicular traffic. Only in recent years the worsening measured. These data allowed to classify the of the morphological impact on the slope as well as landslide across the very slow and slow velocity the increase of road deformations led to recognize classes [3]. The monitoring of ground deformations clearly the existence of a deep-seated landslide also permitted to assess a composite kinematics of involving the whole slope of a secondary hill (237 the landslide body that resulted with differential m a.s.l.), facing westward, down to the Fiumicello displacements, velocities and accelerations. The Torrent valley (15-25 m a.s.l.). Moreover, a greater geological model of the landslide was found to be attention has been paid to this landslide after the conditioned by specific stratigraphic and geo- recognition that a tunnel of a national railway is structural constraints. The landslide involves an exposed to risk because crossing its foot. upper stratigraphic interval of the Saraceno The landslide involves a turbidite series belonging Formation, with a dominant marly-argillaceous to the Saraceno Formation (North-Calabrian composition. The geostructural setting of the tectonic unit), which is comprised of intercalated Formation is intensely folded and faulted but with a calcarenites, marls and argillaceous rocks, with a globally monocline attitude downstream dipping. complexly folded structure. The left flank of the landslide is set on a normal A recent study [28] reconstructed the kinematic fault. Based on the reconstructed model and evolution of the Pisciotta landslide by the considering the variability of the depth of the examination of all available aerial photos, from rupture surfaces, assessed from 30 to 50 m, the 1943 to 2006. Moreover, quantitative analyses of depleted mass and the accumulation volume were ground deformations were executed both estimated in the range 4 ÷ 6 × 106 m3. The almost considering the progressive displacements of the uninterrupted state of activity, existing in the last road, by comparing available contour maps and seventy years at least, the slow kinematics, not yet

ISBN: 978-960-474-376-6 169 Latest Trends in Engineering Mechanics, Structures, Engineering Geology evolved in a paroxysmal global failure stage, and 5 Conclusions the exposition to risk of a railway tunnel make this One of institutional mission of the territory landslide a special case of geo-hazard to be analyzed recognized as Geopark by European and Global further and to be taught in order to increase Geopark Network is the integration of the education and awareness about landslides and geoheritage with natural resources, hazard natural risks. For these reasons the Pisciotta assessment and risk management. Since its landslide can be considered a scientific, didactic and institution and constitution time (1995-1998), the educational “open laboratory” to be included among National Park of Cilento Vallo Diano and Alburni “moving geosites” of the Cilento, Vallo di Diano has dedicated great efforts in the bring together and Alburni Geopark. biodiversity conservation and geodiversity preservation. Starting from these activities, since CVDA Geopark assumed as “grand strategy” the 4 Moving Geosite Project integration between geosite recognition, fruition and The most representative “moving geosite” in the functionality and geological hazard mitigation CVDA Geopark is Roscigno Old Village, also actions and natural resources conservation practice. known as “the walking village” (Fig. 13). The old According to the conclusions of the 12th EGN village, recognized as UNESCO Heritage, was Conference, incoming results about the proposed completely abandoned since the early 20th century, concept “moving geosite”, could be shared with due to a reactivation of a huge and complex slide- other landslide-prone geoparks around the world earth flow landslide, dormant since 4th century BC, [29], where similar projects could be an additional when a previous reactivation affected the ancient, issue of their core mission within research, italic settlement (Fig. 7), located on Mt. education, dissemination and fruition actions hilltop. addressed to awareness in risk management.

References

[1] ISPRA, Landslides in Italy, Special report 2008. Report n. 83, 2008, 32 pp.. [2] Calcaterra D., Di Martire D., Guida D., Landslides in the territory of Geopark. Geopark’s book n. 2, 11-21, National Park of Cilento, Vallo di Diano e Alburni, 2013, ISBN 978-88-907281-0-5. [3] Cruden D.M., Varnes D. J. (1996) - Landslide types and processes. In: Turner A.K., Schuster R.L. (eds.) Landslides: Investigation and Mitigation. Transp. Res. Board, Spec. Rep. 247, 36-75. [4] Leone, F., Aste, J.P., Leroi, E., 1996.

Fig. 7 The Old Roscigno village moving geosite, Vulnerability assessment of elements exposed modified from South Campania RBA Inventory map. For to mass-moving: working toward a better risk legend, see Fig. 2. perception. In: Senneset, K. (ed.). Landslides, Proc. 7th Int. Symp. on Landslides, Trondheim, Following the 2010 surrounding reactivations, an Norway, 263-269. experimental, interdisciplinary, integrated and inter- [5] Nix T. and Marinoni O., 2006 Quantitative institutional project, named “Roscigno Project”, is landslide risk analysis and risk evaluation for going to start, involving, among other institutions, publicly accessible geosites IAEG2006 Paper the CVDA Geopark, as focal institutional support to number 222 2006 The Geol. Society of London. the project [29]. The latter represents the first [6] Margielewski W. and Alexandrowicz Z. (2004) implementation of the Geopark Action Plan in Diversity of landslide morphology as a part of providing a different perception of what usually is geoconservation pattern in The Polish felt as hazardous, by using geodiversity as Carpathians. Polish Geol. Inst. Special Papers, knowledge tool in public awareness raising. 13 (2004): 65–72 Proc. of the Conference “Geological heritage concept, conservation and protection policy in Central Europe”.

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