Debris slides–rapid earth flows in the carbonate massifs of the Campania region (Southern Italy): morphological and morphometric data for evaluating triggering susceptibility
Introduction
In the last few centuries, there have been many debris slides–rapid earth flows in the pyroclastic deposits that cover the steep slopes bordering the main carbonate massif of the western Campania region (Southern Italy).
These landslides were initially triggered by small falls or slides; they subsequently evolved through a slide and an amplification phase due to an “avalanche” effect, and lastly, a rapid flow and accumulation phase took place (Di Crescenzo and Santo, 1998, Di Crescenzo and Santo, 1999). Characterized by high velocity and fluidity, the flows determine highly hazardous situations. They have been widely studied from an applied geology, geomorphological, hydrogeological and geotechnical perspective.
In the literature, mass movements such those under investigation, involving a mixture of water and sediments, are defined as “mud flows”, “hyperconcentrated flows”, “granular flows”, and “debris flows” (Caine, 1980, Guida et al., 1986, Celico et al., 1986, Guadagno, 1991, Takahashi, 1991, WP/WLI, 1993, Pellegrino, 1994, Canuti and Esu, 1995, Cruden and Varnes, 1996, Dikau et al., 1996, Corominas and Moreno, 1998). This suggests that there is little general agreement on how to model and classify such processes. Some researchers (Pierson and Costa, 1987, Costa, 1988, Pierson, 1989, Coussot and Meunier, 1996) classify flows according to their rheological behaviour and therefore their “water/sediment” ratio, whereas others (Johnson, 1970, Johnson and Rodine, 1984, Fleming et al., 1989) consider “debris flow”a generic term for all the different types of flow regardless of the “water/sediment” ratio.
Di Crescenzo and Santo, 1998, Di Crescenzo and Santo, 1999 show that debris slides–rapid earth flows in Campania are always characterized by a limited area where detachment first occurs, a second area where translational sliding occurs and in which the landslide is greatly amplified, and finally, an area of channelization, flow and accumulation. The different phases occur in quick succession; because a rapid earth flow generally quickly follows the initial fall-slide phase, it would be more appropriate to speak of complex “debris slides–rapid earth flows”.
This paper assesses all published data on these debris slides–rapid earth flows and through new “allometric” studies (sensu Gould, 1966, Bull, 1975, Govi, 1977, Church and Mark, 1980, Pasuto et al., 1992), aims at identifying factors, especially morphometric indicators, which can be used to define potential zones of triggering. These parameters can be easily determined and can therefore greatly contribute to landslide hazard studies.
Section snippets
Methods
After consulting scientific papers and historical documents, the areas most recently affected by debris slides–rapid earth flows were analysed by means of aerial photo interpretation and a detailed geological survey. All landslides longer than 300 m which occurred in Campania in the last century (only a few date back to 1770 and 1800) were investigated. Among them, 172 landslides (Table 1) were selected for further geomorphological and morphometric analysis and were mapped at a 1:2000 scale.
General setting
The study area is located on the Tyrrhenian coast of Campania where, during Plio-Quaternary times, important regional faults linked to the extension of the Tyrrhenian area, defined a major tectonic depression named the “Campania graben”. The structural heights delimiting this graben consist of the carbonate peaks of the Sorrento Peninsula–Lattari Hills ridge, the Partenio group Hills, the Caserta Hills, of Pizzo D'Alvano and Mt. Maggiore (Fig. 5). These peaks consist of more than 1500-m-thick
Predisposing factors
The geological and geomorphological survey evidenced a repetitiveness of events along road cuts and rocky cliffs, suggesting the need for a detailed inventory of their number and location (Guadagno and Perriello Zampelli, 2000). As seen in Fig. 7a, about 86% of the 172 investigated landslides developed above or below roads/tracks and rocky cliffs. In particular, the predisposing factor for most channelled landslides was the presence of rocky cliffs, whereas there is a substantial balance in the
Conclusions and perspectives
The analysed landslides are always characterized by a limited area where detachment first occurs, a second area where translational sliding occurs and in which the landslide is greatly amplified, and finally, an area of channelization, flow and accumulation. The different phases occur in quick succession. Because a rapid earth flow generally quickly follows the initial fall or slide phase, it would be more appropriate to speak of complex “debris slides–rapid earth flows”. The study of 172
Acknowledgements
Authors would like to thank the anonymous reviewers, the Guest Editors, Prof. R. de Riso and Prof. N. Santangelo for their stimulating and useful advices.
References (69)
- et al.
Recognition, classification and mechanical description of debris flows
Earth-Sci. Rev.
(1996) - et al.
Transformation of dilative and contractive landslide debris into debris flows—an example from Marin County California
Eng. Geol.
(1989) - et al.
Tephrostratigraphy of the A.D. 79 Pyroclastic deposits in perivolcanic areas of Mt. Vesuvio (Italy)
J. Volcanol. Geotherm. Res.
(1993) - et al.
The Ottaviano eruption of Somma-Vesuvius (8000 y b.p.): a magmatic alternating fall and flow-forming eruption
J. Volcanol. Geotherm. Res.
(1993) - et al.
The Avellino plinian eruption of Somma-Vesuvius (3760 y b.p): the progressive evolution from magmatic to hydromagmatic style
J. Volcanol. Geotherm. Res.
(1993) Le frane dell'amalfitano nel 1924. Cause, effetti e rimedi
Atti Ist. Incoraggiamento Sci.
(1924)- et al.
Osservazioni geomorfologiche sulle frane del 5–6 Maggio 1998 del Pizzo d'Alvano (Monti di Sarno, Campania). Estratto da “Studi geografici e geologici in onore di Severino Belloni”
Genova
(1999) Allometric change of landform
Geol. Soc. Am. Bull.
(1975)The rainfall intensity–duration control of shallow landslides and debris flows
Geogr. Ann.
(1980)- et al.
The January 10, 1997 Pozzano Landslide, Sorrento Peninsula, Italy
Engi. Geol.
(2003)
The May 5th landsliding event in Campania, Southern Italy: inventory of slope movements in the Quindici area
The influence of meteoric events in triggering shallow landslides in pyroclastic deposits of Campania, Italy
Multiple debris flows in volcaniclastic materials mantling carbonate slopes
Historical data analysis of the landsliding and flood events in Campania (Italy), as a tool for the assessment of the landslide hazard
Glossario internazionale per le frane
Riv. Ital. Geotec.
A preliminary model for the landslides of May 1998 in Campania Region
Proposta di un modello interpretativo per lo studio delle frane nei terreni piroclastici
Geol. Appl. Idrogeol.
The influence of vegetation on slope stability
On size and scale geomorphology
Prog. Phys. Geogr.
The dramatic cluster of pyroclastic debris flows which occurred on 5th and 6th May 1998 in the Sarno Mountains (Vesuvius Region, Southern Italy): a geomorphological perspective
Studio delle condizioni di stabilità dei terreni della Penisola Sorrentina
Geol. Appl. Idrogeol.
Mechanism of mudflow: a case study in the Spanish eastern Pyrenees
Rheologic, geomorphic, and sedimentologic differentiation of water floods, hyperconcentrated flows, and debris flows
Landslide types and processes
Sulla franosità della zona sud-occidentale della Penisola Sorrentina (Campania)
Mem. Note Ist. Geol. Appl.
Preliminary report on the landslides of 5 May 1998, Campania, southern Italy
Bull. Eng. Geol. Environ.
Il caso di Quindici (Av) del 5 Maggio 1998 nel quadro dei movimenti di massa distruttivi delle coltri piroclastiche della Campania occidentale
Quad. Geol. Appl.
Cited by (100)
Rainfall infiltration and slope stability of alpine colluvial terraces subject to storms (NE Italy)
2023, Engineering GeologyInsights gained into geo-hydrological disaster management 25 years after the catastrophic landslides of 1998 in southern Italy
2023, International Journal of Disaster Risk ReductionCitation Excerpt :Most of the source areas corresponded to morphological discontinuities represented by natural scarps and road cuts, interrupting the spatial continuity of the pyroclastic deposits [47,50]. Both natural and man-made cuts were among the most important predisposing factors controlling the initial failures during both the 1998 and other similar events occurring in the region [51]. Morphological conditions also controlled the evolution of the instability processes downslope.
Hydraulic characterization of an unsaturated vegetated soil: The role of plant roots and hydraulic hysteresis
2022, Geomechanics for Energy and the EnvironmentCitation Excerpt :The stratigraphic profile observed in the field is composed of a series, 2.5 m thick, of pyroclastic soils resting on fractured limestone. These soil layers are attributable to two different explosive volcanic falls: (i) the shallower younger soil dates to the 79 AD eruption of Mt. Vesuvius; (ii) the deeper older layers are of uncertain origin, but preliminary tephro-stratigraphic data attribute them to a Phlegraean eruption occurring around 130,000 years ago.32 From top to bottom, the stratigraphic sequence consists of the following layers (Fig. 1b–e)16:
Sinkholes, Subsidence and Related Mass Movements
2022, Treatise on Geomorphology