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Introduzione al Progetto MONICA Il progetto per il sistema di monitoraggio integrato della falesia di Coroglio rappresenta una delle azioni previste nell’ambito di un più ampio progetto PON - Ricerca e Competitività 2007-2013 per le Regioni della Convergenza denominato: “MONitoraggio Innovativo per le Coste e l’Ambiente marino (MONICA)”, codice identificativo PON01_01525, recentemente finanziato dal MIUR. Scopo del progetto MONICA è di contribuire efficacemente alla prevenzione e alla gestione delle emergenze ambientali, in particolare quelle marine e costiere, attraverso la realizzazione di un sistema di monitoraggio ambientale innovativo, basato su una infrastruttura di comunicazione in fibra ottica, installata su fondale marino ed in corrispondenza della zona costiera, che colleghi in rete una serie di sensori, sia innovativi che già esistenti [Somma et al., 2013]. L’area di sperimentazione di queste nuove tecnologie è il settore costiero dei Campi Flegrei, corrispondente al Golfo di Pozzuoli, ideale perché caratterizzata da rischio vulcanico, sismico, da maremoto, da movimenti franosi, nonché da rischi antropici quali l’inquinamento e il traffico marittimo. L’area di studio del Progetto MONICA comprende il settore orientale del territorio della Provincia di Napoli, che dal 1° gennaio 2015 lascerà il posto alla Città Metropolitana di Napoli, istituita ai sensi della Legge 7 aprile 2014 n. 56, ed include I territori costieri dei Comuni di Napoli, Pozzuoli, Bacoli e Monte di Procida. Le attività di ricerca dell’IAMC-CNR nell’ambito di questo progetto includono lo sviluppo e la messa a punto di un sistema di monitoraggio innovativo (con tecnologie e metodiche sperimentali) di tratti selezionati della falesia tufacea costiera del litorale Flegreo, al fine di valutarne le condizioni di stabilità e di vulnerabilità generale rispetto ai rischi naturali ed antropici. Nell’ambito del Segmento Costiero del progetto “MONICA” è stata dedicata particolare attenzione allo studio ed al monitoraggio multi-parametrico dell’evoluzione delle falesie tufacee costiere dell’area flegrea, dovuta alle problematiche di instabilità geomorfologica connesse all’interazione tra evoluzione vulcano-tettonica dell’area, trasformazione antropica del territorio e processi di degradazione ed erosione proprie della fascia costiera [Matano et al., sub. EJRS; Matano et al., 2015]. La scelta dei 5 siti di studio (Fig. 1), selezionati per la fase di analisi e monitoraggio dei processi di instabilità sulle falesie costiere, è stata realizzata tenendo conto di numerosi elementi, sia naturali che antropici, in modo da rendere particolarmente proficua l’attività di monitoraggio, nell’ottica di poter mettere a punto un sistema di early warning multirischio, di fondamentale utilità per le popolazioni esposte ai rischi. Lo studio ha fra gli obiettivi principali la verifica sperimentale di modelli teorici della stabilità di costoni tufacei. A tal fine è stato definito un progetto per un sistema di monitoraggio denominato TCM (Tuff Cliff Monitoring), che ha come scopo principale il monitoraggio di stabilità della falesia di Coroglio, lungo la costa dell’area Flegrea, interessata da fenomeni franosi e da distacchi di blocchi di varie dimensioni dalle pareti, e definisce I requisiti principali dell’architettura tipo del sistema di monitoraggio. La scelta per la progettazione e l’installazione del sistema di monitoraggio multiparametrico è ricaduta sulla falesia di Coroglio (Napoli), in quanto ubicata in un’area urbana di interesse nazionale ed è stata interessata in passato da numerosi fenomeni di crollo e scivolamento di blocchi tufacei e da interventi di consolidamento [Somma et al., 2014]. Le attività di studio e progettazione sono state finalizzate all’integrazione di una rete di monitoraggio per: (i) la prevenzione e/o mitigazione dei rischi connessi all’instabilità dei versanti in area costiera; (ii) la validazione dei modelli geotecnici, idrogeologici e metereologici comunemente utilizzati per la quantificazione del rischio; (iii) la gestione delle fasi di emergenza a seguito di un evento calamitoso; (iv) la programmazione delle politiche di gestione territoriale a medio e lungo termine. Nelle attività di monitoraggio costiero considerate nell’ambito del Progetto MONICA è prevista l’utilizzazione sia di sensori innovativi a fibre ottiche che di sensori geotecnici “tradizionali” [Minardo et al. 2012; Gagliardi et al. 2008]. I sensori basati sulla tecnologia delle fibre ottiche verranno installati lungo I costoni per monitorare I parametri fisici che possono costituire I precursori di evento rispetto ai fenomeni di instabilità, come I crolli ed I ribaltamenti [Varnes, 1978; Cruden e Varnes, 1996]. Gli stessi dovranno essere predisposti in maniera tale da considerare le variabili fisiche (umidità, temperatura, vento, ecc.) che potrebbero compromettere le misure. La taratura dei dati ottenuti e la loro affidabilità verrà effettuata attraverso un sistema di monitoraggio parallelo, basato su sensori tradizionali come accelerometri, estensimetri, misure topografiche, ecc. Le procedure, le tecnologie e la sensoristica previste nel progetto possono trovare utile applicazione anche in altri campi “strategici” della sicurezza dei territori urbani e costieri, quali il monitoraggio di infrastrutture ed il controllo della stabilità di edifici e di strutture antropiche.

(U-Th)/He and fission-track analyses of apatite along deep-seated tunnels crossing high-relief mountain ranges offer the opportunity to investigate climate and tectonic forcing on the topographic evolution. In this study, the thermochronologic analysis of a large set of samples collected in the Simplon railway tunnel (western-central Alps; Italy and Switzerland) and along its surface trace, coupled with kinematic and structural analysis of major fault zones intersecting the tunnel, constrains the phenomena controlling the topographic and structural evolution, during the latest stage of exhumation of the Simplon Massif, and the timing in which they operated. The study area is located at the western margin of the Lepontine metamorphic dome where a complex nappe-stack pertaining to the Penninic and Ultrahelvetic domains experienced a fast exhumation from the latest Oligocene onward. The exhumation was mainly accommodated by a west-dipping low-angle detachment (the Simplon Fault Zone) which is located just 8 km to the west of the tunnel. However, along the section itself several faults related to two principal phases both with important dip-slip kinematics have been detected. Cooling rates derived from our thermocronological data vary from about 10 °C/Ma at about 10 Ma to about 35 °C/Ma in the last 5 Ma. Such increase in the cooling rate corresponds to the most important climatic change recorded in the northern hemisphere in the last 10 Ma, i.e. the shift to wetter conditions at the end of the Messinian salinity crisis and the inception of glacial cycles in the northern hemisphere. In addition, (U-Th)/He and fission-track age patterns lack of important correlation with the topography suggesting that the present-day relief morphology is the result of recent erosional dynamics. More in details, the (U-Th)/He tunnel ages show an impressive uniformity at 2 Ma, whereas cooling rates calculated at 1 Ma increase towards the two major valleys. This indicates a focusing of erosive processes in the valleys which led to the shaping of present-day topography. Structural analysis documents the presence of two phases of brittle deformation postdating the metamorphic phases in the area. The first one is directly related to the last phase of activity along the Simplon Fault Zone and is characterized by extension towards SO and vertical shortening. The young one is characterized by extension towards NO and horizontal shortening in a along the NE-SO direction. Structures related to the first phase of brittle deformation generate important variations in the older ages' dataset, until 3 Ma, suggesting that tectonics controlled rocks exhumation up to that age. Structures related to the second phase generate some variations also in the younger age dataset, highlighting the activity of faults bordering the massif and suggesting a continuous activity also after 2 Ma. However, most of (U-Th)/He tunnel ages, varying slightly around 2 Ma, document that the Simplon area has experienced primarily erosional exhumation in this time span. In conclusion, all our data suggest that in the central Italian Alps the climatic signal gradually overrode the tectonic effects after about 5 Ma, as a consequence of the climatic instability started at end of Messinian salinity crisis and improved by the onset of glaciations in the northern hemisphere.

The long-lasting earthquake sequence of Central Italy in 2016 triggered around 1370 landslides, most of which were observed close to ridge areas. The area of San Pellegrino di Norcia (PG) was badly affected by the 6.5 Mw Norcia earthquake that triggered 95 rock falls and slides with volumes ranging from 0.5 m3 to 380 m3 over an area of 0.6 km2. The presence of such a large number of coseismic landslides in a small area provided a suitable case study for investigating triggering mechanisms related to slope morphology and the subsequent propagation dynamics of rockfalls. To this aim, detailed field data collection and up-to-date terrain modelling based on Unmanned Aerial Vehicle (UAV) imagery were carried out. They permitted to perform morphometric analyses oriented at defining: (a) the frequency of occurrence of rockfall with reference to the energy relief, (b) the relationships between extensions of source and propagation areas and (c) the change in the shape of the propagation area as a function of the different terrains crossed by rockfalls. The results of the morphometric study were compared with dynamic analyses of rock-slides onset and simulations of rockfall propagation. They highlighted that, disregarding the presence of steep rock faces, the failures were located close to ridge and slope edges, thus pointing out the role of topography on triggering of landslides. Moreover, it was possible to observe that even small-sized rockfalls had a widening effect in the foothill characterized by longer runouts compared to rockfall simulations. This issue was due to the mobilization of the talus debris covering the limestone bedrock. This study investigates an area where a significant increase in rockfall hazard can be expected due to the coupled effect of topographic amplification and debris remobilization.

This paper presents a study to evaluate the collapse susceptibility of a karst cave located along a slope on the Amalfi coast (southern Italy) and the presumable geomorphological evolution of the whole slope as a result of cave roof collapse. In the study area, several natural karst caves with volumes varying between 1000 and > 10,000 m 3 were inventoried and the most likely genetic processes were identified. Some of them proved to be remnants of already collapsed caves, while others were in precarious stability conditions. The caves are usually located upslope or very close to the main populated resorts. A detailed geological, geomorphological and geostructural study was performed on a very wide, deep cave (called the “Saraceno” cave), on which the resort town of Conca de' Marini has been built. The study was carried out through a multidisciplinary approach, which included classical field geological observations, sometimes requiring the support of rock-climbing geologists, experts in photogrammetric surveys and terrestrial laser scanning techniques (TLS). TLS surveys allowed the reconstruction of an accurate geometric and geostructural model of the cave and its relationship with the upslope Conca de' Marini resort. Furthermore, it allowed the thickness of the cave overburden to be determined in detail; ground surfaces most susceptible to collapse were also identified. In the event of possible widespread collapse, several buildings and transportation infrastructures could be involved. As the cave is located on a very steep slope, a debris avalanche could be triggered in the event of a catastrophic failure, and the landslide debris, characterized by a presumably high magnitude and velocity, could involve a wide slope area down to the coast. The failure evolution could be very similar to that which took place in Amalfi in the late 19th century.

This short note presents an approach to assess rockfall susceptibility based on terrestrial laser scanner (TLS) point cloud data at the cliff scale. The test area is coastal cliff situated in the southern part of the Campania Region (Centola Municipality, SW Italy), in which a natural arch was formed. Since this coastal area constitutes an important tourist attraction, a large number of people rest on a daily basis beneath the cliffs, increasing considerably the risk associated to rockfalls. The Terrestrial Laser Scanner (TLS) survey of the cliff was realized in june 2015. A structural analysis of the cliff was performed on the point cloud using Coltop 3D software. The different characteristics defining the discontinuity sets were extracted, including orientation, spacing and persistence. The kinematically unstable areas were mapped using a script that computes an index of susceptibility to rockfalls based on the spatial distribution of failure mechanisms. Results show that the kinematically feasible failures are not equally distributed along the cliff. The most important discontinuity set in terms of potential planar failure is K10 (71/097), for the toppling is K1 (60/218). The combination of K10 and K1 has the highest value of susceptibility for wedge failure.