Abstract

This paper contains the results of geological, geomorphological and geological-technical studies carried out on the largest landslide to have taken place on 5th May 1998 in Tavernole, on the western outskirts of the S. Felice a Cancello village (Campania, Southern Italy). The landslide occurred in concurrence with other catastrophic events in the Sarno mountains. On the whole, based on its morphological and sedimentological features together with overall kinematics, the studied landslide has been considered as a typical debris flow sensu Johnson & Rodine (1984), Pearson & Costa (1987) and Cruden & Varnes (1994). The area studied is part of the extreme western sector of the carbonate ridge of the Avella mountains. More specifically, it is bordered by the northern slope of the E-W ridge between Mt. S. Angelo Palomba and the castle of Cancello (Caserta) (cfr. figs. 1 and 2). This slope--which terminates in a series of (often rather steep) normal faults--is part of an essentially calcareous succession of carbonate platform facies and is covered by mainly continuous, essentially Holocene, detrital-colluvial deposits (up to 20 meters thick) of prevalently volcaniclastic composition. The landslide originated at a height of about 330 m a.s.l. and quickly moved down the valley involving the volcaniclastic sediments covering the carbonate substratum. Shortly before stopping in the area of flat land opposite the foot of the slope (about 70 m a.s.l.), the flow destroyed several specialized crops and an industrial warehouse. A neighbouring warehouse was also damaged. The volume of debris carried by the slide can be estimated at around 60,000 cubic metres. The slide caused the total dislodgement of the surface deposits which covered the underlying carbonate substratum and thus permitted observation of the subsurface layer. The exposed slope showed an emerging substratum composed of a whitish and hazel-coloured Lower Cretaceous well-bedded shallow-water limestones and dolostones, that locally show a clear cyclical arrangement of subtidal-intertidal lithofacies. The substratum was affected by a widespread and considerable structural warp caused by mainly NW-SE and E-W joints and shear planes. The first Apennine-oriented shear plane system was associated with a significant displacement which enabled identification of three structural blocks (fig. 5). In the middle-low sector of the surface from which the fast-moving debris flow was formed, the calcareous substratum was covered by two generations of continental breccia of different ages and depositional setting. The older rock, arranged in seams and sills, mainly covered the central block, while the more recent rock--which consisted of well-cemented breccia with inclined stratification--was extensively present above the central and lower structural block. The most recent breccias probably date back to the cold periods of the final Middle and Upper Pleistocene age. The carbonate substratum and the second generation continental breccias (where present) were covered by essentially recent detrital-colluvial sediments, composed of reworked volcaniclastic material, carbonate clasts and by late-Quaternary pyroclastic deposits in primary bedding. The latter were generally found in the middle-high part of the slope, while the reworked pyroclasts were found mainly at the foot of the slope in gullies and morphological depressions....

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