Lineamenti morfodinamici e sedimentari del litorale dei Campi Flegrei (Campania, Italia meridionale)

L’area in esame può essere suddivisa in tre settori a caratteri nettamente differenziati, il litorale di Cuma, che ne segna il limite occidentale,il Golfo di Pozzuoli, che ne costituisce la fascia orientale più complessa ed articolata ed il litorale di Miliscola che ne rappresenta il raccordo centrale.Il litorale di Cuma. Esteso per oltre 6 km con orientamento N-S, questo settore costituisce la porzione terminale della piana costiera delF. Volturno, la cui foce è situata circa 20 km più a NW. Le spiagge basse e sabbiose sono limitate verso l’interno da cordoni dunari inparte allo stato naturale ed in parte fortemente antropizzati. L’evoluzione recente (periodo 1980-1998) è marcata da un arretramento generalizzato nel periodo 1980-1987 seguito da una tendenza all’avanzamento nel successivo periodo 1987-1998, con valori decrescentiprocedendo da N verso S.Il litorale di Miliscola. Si estende con orientamento W-E per circa 2 km tra i promontori di Monte di Procida e di Capo Miseno ed è limitatoverso l’interno da un lago costiero (lago di Miseno). In conseguenza ad una forte crisi erosiva che aveva colpito l’area alla metà degli anni ’70 sono state costruite tra il 1980 e il 1988 otto piattaforme-isole che hanno indotto un'accentuata ricostituzione della spiaggia a tergo delle opere; nella parte orientale del settore (verso Capo Miseno), dove tali opere sono assenti, si instaura una tendenza di tipo erosionale.Il Golfo di Pozzuoli. Esteso per oltre 9 km, configura due ampie falcature semicircolari ad andamento E-W, costituite da coste alte e rocciose alternate a coste basse e sabbiose di limitata ampiezza. Profonde sono le modificazioni naturali ed antropiche rilevabili in questo settore: tra le prime si ricordano i fenomeni bradisismici che hanno interessato l'area fin dall'antichità portando alla sommersione dinotevoli porzioni di territorio litoraneo, tra le seconde una urbanizzazione talmente spinta da stravolgere completamente l’assetto geoambientale naturale della fascia costiera.

Morphodynamical and sedimentary features of the coast of the Phlegrean Fields (Campania, Southern Italy). The Phlegrean Fields areone of the most famous volcanic areas in the world. During the last 50,000 years this area has been formed by the activity of many eruptive centres and today it has the typical morphology of a volcanic field. At present the Phlegrean Fields are active, even if the last event was recorded a long time ago: the Monte Nuovo eruption in 1538. The endogenous activity is currently recorded by the frequent inversions of the vertical crustal movements (bradyseism), by the sismicity connected to the bradyseismic events and by the intense thermal activity. From the Roman Age up to this time the features of the bradyseismic events have not been defined yet because of the type and complexity of the phenomena; recent research shows that the greatest submersion (17÷18 m) was verified during the early Middle Ages. After the resurgence phase the ground has risen only 6÷7 m: the presence of the submerged Roman ruins shows the extent of the sinking.The coastal area could be divided into three clearly diversified sectors: the shore of Cuma constituting the western boundary; the Gulf of Pozzuoli representing the eastern zone, more complex and articulate; the shore of Miliscola, the central connection between the two preceeding sectors.The shore of Cuma.This sector, extending for about 6 km with N-S orientation between Licola Mare and Monte di Procida promontory,constitutes the terminal part of the coastal plain of the Volturno River, which flows approximately 20 km to the NW. The low and sandy beaches are limited inland from some foredune ridges, partly natural and partly urbanized. In the northern sector, behind the foredune ridges, there is a wide swampy area reclaimed during the last century ("Mazzoni area and Licola Lake") and in the southern sector there is the Fusaro coastal Lake. In the central part the promontory of Cuma interrupts the outline of the coast; this promontory was the centre of the Acropolis during the Greek-Roman Age, but today the Acropolis has almost entirely disappeared. Within the depth of 5 mthe submarine beach shows one or two bar-trough systems: the inner one is crescentic and frequently connected to the rhythmic topography of the shoreline, while the outer one is linear and situated at a distance of about 100 m from the coast. A gentle slope characterizes the submarine beach beyond the bar-trough zone. The evolution of the shoreline presents a general erosional tendency during theyears 1980-1987, whereas a tendency to the progradation is evident during the years 1987-1998. The prevailing wind sector is delimited by the 180°-330°N azimuth; most storms are come in from the 270°-300°N sector.The shore of Miliscola.The shore of Miliscola is situated between the Monte di Procida and Capo Miseno promontories and has anextension of approximately 2 km; it is limited inland from the Miseno coastal Lake. In the western tract we can find various defenceworks, while in the eastern tract a wide beach is evident. The submarine beach is characterized by a small bar-trough system within the3 m depth and within a distance of less than 75 m from the coast. Eight circular break waters have been built from 1980 to 1988 becauseof strong erosion during the middle '70ies; in these years these defence works have brought an evident beach restoration. Afterwhich, until 1996, the shoreline position behind the break waters has remained substantially unchanged, while in the eastern part of thesector (toward Capo Miseno) an erosional tendency was observed with a value of 0.5 m/y.The Gulf of Pozzuoli.This sector, extending for over 9 km and forming two large semi-circular zones with an W-E orientation, shows high and rocky coasts alternated with small, low sandy beaches. The prevailing wind sector is delimited by the 120°N and the 200°Nazimuth; the significant waves come by the 120°-130°N and 180°N azimuth; the maximum fetch and the greatest energetic potential concerns the 180°N azimuth. In this area the modifications are very evident, natural as well as and anthropic. Among the natural ones there are the bradyseismic events, that have caused the submersion of entire coastal tracts (for instance: the structures of the PortusIulius, the harbour of the ancient Roman imperial navy) and the Monte Nuovo eruption in 1538, that changed the coastal configurationin the western zone of the Gulf. Among the anthropic ones there is a strong urbanization (“ILVA” iron and steel industry, various defencework, artificial coastal platforms) that has completely destroyed the natural environment of the area.