Some observations on the prediction of the dynamic parameters of debris flows in pyroclastic deposits in the Campania region of Italy

Abstract. On 15–16 December 1999, heavy rainfall severely stroke Campania region (southern Italy), triggering numerous debris flows on the slopes of the San Martino Valle Caudina-Cervinara area. Soil slips originated within the weathered volcaniclastic mantle of soil cover overlying the carbonate skeleton of the massif. Debris slides turned into fast flowing mixtures of matrix and large blocks, downslope eroding the soil cover and increasing their original volume. At the base of the slopes, debris flows impacted on the urban areas, causing victims and severe destruction (Vittori et al., 2000). Starting from a recent study on landslide risk conditions in Campania, carried out by the Regional Authority (PAI –Hydrogeological setting plan, in press), an evaluation of the debris-flow susceptibility has been performed for selected areas of the above mentioned villages. According to that study, such zones would be in fact characterised by the highest risk levels within the administrative boundaries of the same villages ("HR-zones"). Our susceptibility analysis has been performed by applying SCIDDICA S3–hex – a hexagonal Cellular Automata model (von Neumann, 1966), specifically developed for simulating the spatial evolution of debris flows (Iovine et al., 2002). In order to apply the model to a given study area, detailed topographic data and a map of the erodable soil cover overlying the bedrock of the massif must be provided (as input matrices); moreover, extent and location of landslide source must also be given. Real landslides, selected among those triggered on winter 1999, have first been utilised for calibrating SCIDDICA S3–hex and for defining "optimal" values for parameters. Calibration has been carried out with a GIS tool, by quantitatively comparing simulations with actual cases: optimal values correspond to best simulations. Through geological evaluations, source locations of new phenomena have then been hypothesised within the HR-zones. Initial volume for these new cases has been estimated by considering the actual statistics of the 1999 landslides. Finally, by merging the results of simulations, a deterministic susceptibility zonation of the considered area has been obtained. In this paper, aiming at illustrating the potential for debris-flow hazard analyses of the model SCIDDICA S3–hex, a methodological example of susceptibility zonation of the Vallicelle HR-zone is presented.

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Seasonal effects of rainfall on the shallow pyroclastic deposits of the Campania region (southern Italy)

Landslides ◽

10.1007/s10346-013-0395-3 ◽

2013 ◽

Vol 11 (5) ◽

pp. 779-792 ◽

Cited By ~ 61

Author(s):

Leonardo Cascini ◽

Giuseppe Sorbino ◽

Sabatino Cuomo ◽

Settimio Ferlisi

Keyword(s):

Southern Italy ◽

Seasonal Effects ◽

Pyroclastic Deposits ◽

Campania Region

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A probabilistic model for assessing debris flow propagation at regional scale: a case study in Campania region, Italy

10.5194/egusphere-egu21-2224 ◽

2021 ◽

Author(s):

Luca Crescenzo ◽

Gaetano Pecoraro ◽

Michele Calvello ◽

Richard Guthrie

Keyword(s):

Debris Flow ◽

Debris Flows ◽

Regional Scale ◽

Erosion And Deposition ◽

Campania Region ◽

Source Areas ◽

Model Input ◽

Travel Path ◽

Debris Avalanches ◽

Modelling Approach

<p>Debris flows and debris avalanches are rapid to extremely rapid landslides that tend to travel considerable distances from their source areas. Interaction between debris flows and elements at risk along their travel path may result in potentially significant destructive consequences. One of the critical challenges to overcome with respect to debris flow risk is, therefore, the credible prediction of their size, travel path, runout distance, and depths of erosion and deposition. To these purposes, at slope or catchment scale, sophisticated physically-based models, appropriately considering several factors and phenomena controlling the slope failure mechanisms, may be used. These models, however, are computationally costly and time consuming, and that significantly hinders their applicability at regional scale. Indeed, at regional scale, debris flows hazard assessment is usually carried out by means of qualitative approaches relying on field surveys, geomorphological knowledge, geometric features, and expert judgement.</p><p>In this study, a quantitative modelling approach based on cellular automata methods, wherein individual cells move across a digital elevation model (DEM) landscape following behavioral rules defined probabilistically, is proposed and tested. The adopted model, called LABS, is able to estimate erosion and deposition soil volumes along a debris flow path by deploying at the source areas autonomous subroutines, called agents, over a 5 m spatial resolution DEM, which provides the basic information to each agent in each time-step. Rules for scour and deposition are based on mass balance considerations and independent probability distributions defined as a function of slope DEM-derived values and a series of model input parameters. The probabilistic rules defined in the model are based on data gathered for debris flows and debris avalanches that mainly occurred in western Canada. This study mainly addresses the applicability and the reliability of this modelling approach to areas in southern Italy, in Campania region, historically affected by debris flows in pyroclastic soils. To this aim, information on inventoried debris flows is used in different study areas to evaluate the effect on the predictions of the model input parameter values, as well as of different native DEM resolutions.</p>

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The remarkable volcanism of Shastina, a stratocone segment of Mount Shasta, California

Geosphere ◽

10.1130/ges02080.1 ◽

2020 ◽

Vol 16 (5) ◽

pp. 1153-1178

Author(s):

Robert L. Christiansen ◽

Andrew T. Calvert ◽

Duane E. Champion ◽

Cynthia A. Gardner ◽

Judith E. Fierstein ◽

...

Keyword(s):

Debris Flows ◽

Crustal Contamination ◽

Liquid Composition ◽

Pyroclastic Flows ◽

The West ◽

Pyroclastic Deposits ◽

North Side ◽

Eruptive Episode ◽

Central Crater ◽

Nearly Continuous

Abstract Mount Shasta, a 400 km3 volcano in northern California (United States), is the most voluminous stratocone of the Cascade arc. Most Mount Shasta lavas vented at or near the present summit; relatively smaller volumes erupted from scattered vents on the volcano’s flanks. An apron of pyroclastic and debris flows surrounds it. Shastina, a large and distinct cone on the west side of Mount Shasta, represents a brief but exceptionally vigorous period of eruptive activity. Its volume of ∼13.5 km3 would make Shastina itself one of the larger Holocene Cascade stratovolcanoes. Its andesite-dacite lavas average 63 wt% SiO2 and have little compositional or petrographic variation; they erupted almost entirely from one central vent, although a single vent below Shastina’s north side erupted a flow of the same composition. Eruptions ended with explosive enlargement and breaching of the central crater and successive emplacement of four, more-silicic dacite domes within the crater and pyroclastic flows down its flank. Black Butte, a large volcanic dome and pyroclastic complex below the west flank of Shastina, is petrographically and chemically distinct but only slightly younger than Shastina itself, part of a nearly continuous Shastina–Black Butte eruptive episode. Shastina overlies the widespread pumice of Red Banks, erupted from the Mount Shasta summit area and 14C dated at ca. 10,900 yr B.P. (calibrated). Shastina and Black Butte pyroclastic deposits have calibrated 14C ages indistinguishable from one another at ca. 10,700 cal. yr B.P. A cognate granitic-textured inclusion in a late Shastina lava flow yields a 238U-230Th date on zircons within error of those ages. Our conclusion that the entire, voluminous Shastina–Black Butte episode lasted no more than a few hundred years is confirmed by almost identical remanent magnetic directions of all of the lavas and pyroclastic deposits. Although extremely similar, the remanent magnetic directions do reveal a short path of secular variation through the eruptive sequence. We conclude that the entire Shastina–Black Butte eruptive episode lasted no more than ∼200 yr. The magmas that produced the Shastina and Black Butte eruptions were separate individual bodies at different crustal levels. Each of these eruptive sequences probably represents magma approximating a liquid composition that experienced only minimal differentiation or crustal contamination and remained separated from the main central conduit for most eruptions of Mount Shasta. The probability of another rapidly developing, brief but voluminous eruptive episode at Mount Shasta is low but should not be ignored in evaluating future possible eruptive hazards.

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Multiple Effects of Intense Meteorological Events in the Benevento Province, Southern Italy

Water ◽

10.3390/w11081560 ◽

2019 ◽

Vol 11 (8) ◽

pp. 1560 ◽

Cited By ~ 3

Author(s):

Paola Revellino ◽

Luigi Guerriero ◽

Neri Mascellaro ◽

Francesco Fiorillo ◽

Gerardo Grelle ◽

...

Keyword(s):

Soil Erosion ◽

Debris Flows ◽

Southern Italy ◽

Statistical Characteristics ◽

Total Rainfall ◽

Campania Region ◽

Rainfall Events ◽

Pattern Distribution ◽

The Town ◽

Flooded Areas

In October 2015, two intense rainfall events hit the central and southern regions of Italy and triggered a combination of different and widespread effects, including floods, landslides, and soil erosion. These outcomes devastated about 68 municipalities of the Benevento province (Campania region), killed two people, and caused millions of euros worth of damage to structures, infrastructures, and agriculture. The town of Benevento was one of the sectors most affected by overflow. Extensive areas characterized by flyschoid outcrops experienced widespread occurrences of soil erosion and landslides, and destructive, high-velocity debris flows (about 50) afflicted areas that had experienced heavy rainfall of higher intensity (total rainfall of 415.6 mm). In this study, the characteristics of these rainfall events and related geomorphological processes were determined by (i) analyzing the available rainfall data to identify the spatial pattern, distribution, and statistical characteristics of the two storms and (ii) mapping the storm effects, such as flooded areas, landslide types, and soil erosion. These effects were then related to the spatial distribution of the storms and the local geological and geomorphologic settings that drove their initiation and development.

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Rainstorm Magnitude and Debris Flows in Pyroclastic Deposits Covering Steep Slopes of Karst Reliefs in San Martino Valle Caudina (Campania, Southern Italy)

Water ◽

10.3390/w13162274 ◽

2021 ◽

Vol 13 (16) ◽

pp. 2274

Author(s):

Guido Leone ◽

Pasquale Clemente ◽

Libera Esposito ◽

Francesco Fiorillo

Keyword(s):

Time Series ◽

Debris Flow ◽

Debris Flows ◽

Southern Italy ◽

Distribution Functions ◽

Annual Rainfall ◽

Standard Normal Distribution ◽

Relative Significance ◽

Campania Region ◽

Steep Slopes

Debris flows that have occurred in the area of San Martino Valle Caudina (Campania, Southern Italy) are described by geomorphological and hydrological analyses, focusing on the recent event of December 2019. This area can be considered a key example for studying debris-flow phenomena involving the pyroclastic mantle that covers the karstified bedrock along steep slopes. A hydrological analysis of the time series of the maximum annual rainfall, of durations of 1, 3, 6, 12 and 24 h, was carried out based on a new approach to assess rainstorm magnitude. It was quantified by measuring the deviation of the rainfall intensity from the normal conditions, within a specified time period. As the time series of annual maxima are typically skewed, a preliminary transformation is needed to normalize the distribution; to obtain the Z-value of the standard normal distribution, with mean µ = 0 and standard deviation σ = 1, different probability distribution functions were fitted to the actual data. A specific boxplot was used, with box width Z = ±1 and whiskers length Z = ±2. The deviations from these values provide the performance of the distribution fits. For the normalized time series, the rates shown by the trends and relative significance were investigated for the available time series of 11 rain gauges covering the Western–Central Campania region. The most critical condition for the debris-flow initiation appears to occur when a severe or extreme rainfall has a duration ≥ 12 h. The trend analysis did not detect statistically significant increases in the intensity of the rainfall of duration ≥ 6 h.

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Debris avalanches and debris flows of the Campania Region (southern Italy)

Debris-flow Hazards and Related Phenomena - Springer Praxis Books ◽

10.1007/3-540-27129-5_19 ◽

2007 ◽

pp. 489-518 ◽

Cited By ~ 12

Author(s):

Francesco M. Guadagno ◽

Paola Revellino

Keyword(s):

Debris Flows ◽

Southern Italy ◽

Campania Region ◽

Debris Avalanches

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The mobility of some debris flows in pyroclastic deposits of the northwestern Campanian region (southern Italy)

Bulletin of Engineering Geology and the Environment ◽

10.1007/s10064-004-0244-7 ◽

2004 ◽

Vol 63 (4) ◽

pp. 293-302 ◽

Cited By ~ 24

Author(s):

P. Budetta ◽

R. de Riso

Keyword(s):

Debris Flows ◽

Southern Italy ◽

Pyroclastic Deposits

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Experimental study on the rheological behaviour of debris flow

Natural Hazards and Earth System Science ◽

10.5194/nhess-10-2507-2010 ◽

2010 ◽

Vol 10 (12) ◽

pp. 2507-2514 ◽

Cited By ~ 28

Author(s):

A. Scotto di Santolo ◽

A. M. Pellegrino ◽

A. Evangelista

Keyword(s):

Debris Flow ◽

Yield Stress ◽

Debris Flows ◽

Soil Mechanics ◽

Rheological Behaviour ◽

Simple Relation ◽

Campania Region ◽

Failure Behaviour ◽

Fluid Behaviour

Abstract. A model able to describe all the processes involved in a debris flow can be very complex owing to the sudden changing of the material that turns from solid into liquid state. The two phases of the phenomenon are analysed separately referring to soil mechanics procedures with regard to the trigger phase, and to an equivalent fluid for the post-failure phase. The present paper is devoted to show the experimental results carried out to evaluate the behaviour assumed by a pyroclastic-derived soil during the flow. A traditional fluid tool has been utilized: a standard rotational rheometer equipped with two different geometries. The soils tested belong to deposits that cover the slopes of the Campania region, Italy, often affected by debris flows. The influence of solid concentration Cv and grain size distribution was tested: the soils were destructurated, sieved and mixed with water starting from the in situ porosity. All material mixtures showed a non-Newtonian fluid behaviour with a yield stress τy that increases with a solid volumetric concentration and decreases for an increase of sand fraction. The experimental data were fitted with standard model for fluids. A simple relation between Cv and τy was obtained. The yield stress seems to be a key parameter for describing and predicting the post-failure behaviour of debris flows. These results suggest that in the field a small change in solid fraction, due to rainfall, will cause a slight decrease of the static yield stress, readily inducing a rapid flow which will stop only when the dynamic yield stress is reached, namely on a much smoother slope. This can explain the in situ observed post-failure behaviour of debris flows, which are able to flow over very long distances even on smooth slopes.

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