47 research outputs found
Large rock slides in impact craters on the Moon and Mercury
No full textImpact craters are the most common surface features on the Moon and Mercury. On these two bodies, we recognized and mapped large landslides on the walls of impact craters. Through visual inspection of high-resolution imagery, we compiled an inventory of 60 landslides on the Moon and a second inventory of 58 landslides on Mercury. Adopting categories used to catalog terrestrial mass movements, we classified the landslides on the Moon and Mercury as rock slides. We determined the probability density distribution of their planimetric area, and we compared the distributions with similar distributions for terrestrial and martian landslides using data from the literature. We found that rock slides mapped in impact craters on the Moon are, on average, larger than analogous rock slides on Mercury. The relationship between the area of the individual rock slides and the area of the hosting crater suggests that rock slides on Mercury initiate in smaller craters. We hypothesize that the above findings are an effect of the weaker surface gravity of the Moon compared to that of Mercury and/or an effect of the rock material properties
Statistical approaches for the definition of landslide rainfall thresholds and their uncertainty using rain gauge and satellite data
No full textModels for forecasting rainfall-induced landslides are mostly based on the identification of empirical rainfall thresholds obtained exploiting rain gauge data. Despite their increased availability, satellite rainfall estimates are scarcely used for this purpose. Satellite data should be useful in ungauged and remote areas, or should provide a significant spatial and temporal reference in gauged areas. In this paper, the analysis of the reliability of rainfall thresholds based on rainfall remote sensed and rain gauge data for the prediction of landslide occurrence is carried out. To date, the estimation of the uncertainty associated with the empirical rainfall thresholds is mostly based on a bootstrap resampling of the rainfall duration and the cumulated event rainfall pairs (D,E) characterizing rainfall events responsible for past failures. This estimation does not consider the measurement uncertainty associated with D and E. In the paper, we propose (i) a new automated procedure to reconstruct ED conditions responsible for the landslide triggering and their uncertainties, and (ii) three new methods to identify rainfall threshold for the possible landslide occurrence, exploiting rain gauge and satellite data. In particular, the proposed methods are based on Least Square (LS), Quantile Regression (QR) and Nonlinear Least Square (NLS) statistical approaches. We applied the new procedure and methods to define empirical rainfall thresholds and their associated uncertainties in the Umbria region (central Italy) using both rain-gauge measurements and satellite estimates. We finally validated the thresholds and tested the effectiveness of the different threshold definition methods with independent landslide information. The NLS method among the others performed better in calculating thresholds in the full range of rainfall durations. We found that the thresholds obtained from satellite data are lower than those obtained from rain gauge measurements. This is in agreement with the literature, where satellite rainfall data underestimate the “ground” rainfall registered by rain gauges
Methods and tools for landslide forecasting and risk mitigation, and adaptation strategies
No full textThere is worldwide a mounting interest towards the operational forecasting of landslides, with particular regard to rainfall induced landslides. The main reason for this is the fact that landslides represent a serious hazard in many areas, and cause significant and repeated damage and economic losses to the society, posing substantial risks to people and infrastructure. Starting from these considerations, we recently started a IPL project initiative (IPL‐206) on rainfall induced landslides and their consequences, (i) to review past and existing operational landslide forecasting and warning systems, (ii) to propose recommendations for the design, the implementation, and the validation of operational landslide forecasting and warning systems, and (iii) to identify the best procedure for decision making when information from different source are available. Past and existing operational landslide forecasting and warning systems are being examined with these aims, highlighting their distribution in the different countries/continents, their level of accuracy during past events, the effective adoption of the systems by local authorities and the forensic aspects during the operation phase. Follow this first analysis, recommendations for the design, the implementation, and the validation of operational landslide forecasting and warning systems will be proposed. The project is addressed to all those governmental and administrative bodies in charge of the land management and dealing with civil protection issues. These could use the project outcomes, in direct cooperation with scientific bodies, to design, implement, and validate landslide early warning systems, personalized in function of the main physical and meteorological characters of their own areas of study/interest, aimed at attempting to mitigate the risk related to landslides through the adoption of the most suitable strategies
Automated reconstruction of rainfall events responsible for shallow landslides
No full textOver the last 40 years, many contributions have
identified empirical rainfall thresholds (e.g. rainfall intensity
(I ) vs. rainfall duration (D), cumulated rainfall vs. rainfall
duration (ED), cumulated rainfall vs. rainfall intensity (EI))
for the possible initiation of shallow landslides, based on
local and global inventories. Although different methods to
trace the threshold curves have been proposed and discussed
in literature, a systematic study to develop an automated procedure
to select the rainfall event responsible for the landslide
occurrence has only rarely been addressed. Objective
criteria for estimating the rainfall responsible for the landslide
occurrence play a prominent role on the threshold values.
In this paper, two criteria for the identification of the
effective rainfall events are presented. The first criterion is
based on the analysis of the time series of rainfall mean intensity
values over 1 month preceding the landslide occurrence.
The second criterion is based on the analysis of the trend
in the time function of the cumulated mean intensity series
calculated from the rainfall records measured through rain
gauges. The two criteria have been implemented in an automated
procedure that is written in the R language. A sample
of 100 shallow landslides collected in Italy from 2002
to 2012 was used to calibrate the procedure. The cumulated
event rainfall (E) and duration (D) of rainfall events that triggered
the documented landslides are calculated through the
new procedure and are fitted with power law in the D, E diagram.
The results are discussed by comparing the D, E pairs
calculated by the automated procedure and the ones by the
expert method
Automated reconstruction of rainfall events responsible for shallow landslides
No full textOver the last 40 years, many contributions have
identified empirical rainfall thresholds (e.g. rainfall intensity
(I ) vs. rainfall duration (D), cumulated rainfall vs. rainfall
duration (ED), cumulated rainfall vs. rainfall intensity (EI))
for the possible initiation of shallow landslides, based on
local and global inventories. Although different methods to
trace the threshold curves have been proposed and discussed
in literature, a systematic study to develop an automated procedure
to select the rainfall event responsible for the landslide
occurrence has only rarely been addressed. Objective
criteria for estimating the rainfall responsible for the landslide
occurrence play a prominent role on the threshold values.
In this paper, two criteria for the identification of the
effective rainfall events are presented. The first criterion is
based on the analysis of the time series of rainfall mean intensity
values over 1 month preceding the landslide occurrence.
The second criterion is based on the analysis of the trend
in the time function of the cumulated mean intensity series
calculated from the rainfall records measured through rain
gauges. The two criteria have been implemented in an automated
procedure that is written in the R language. A sample
of 100 shallow landslides collected in Italy from 2002
to 2012 was used to calibrate the procedure. The cumulated
event rainfall (E) and duration (D) of rainfall events that triggered
the documented landslides are calculated through the
new procedure and are fitted with power law in the D, E diagram.
The results are discussed by comparing the D, E pairs
calculated by the automated procedure and the ones by the
expert method
Soglie pluviometriche per l’innesco di fenomeni franosi alla scala nazionale e regionale: il caso del Sub-Appennino Dauno (Puglia settentrionale).
No full textIl presente lavoro illustra i risultati allo
stato ottenuti nelle attività di defi nizione di
soglie pluviometriche preliminari per il possibile
innesco di frane superfi ciali nell’area
del Sub-Appennino Dauno (Puglia settentrionale)
avviate dall’Istituto di Ricerca per la
Protezione Idrogeologica (CNR IRPI) in collaborazione
con il Centro Funzionale Decentrato
del Servizio Protezione Civile della Regione
Puglia nell’ambito del progetto nazionale
“Soglie Pluviometriche per il possibile innesco
di fenomeni franosi superfi ciali” previsto
dall’intesa operativa tra il Dipartimento della
Protezione Civile (DPC) e l’IRPI, Centro di
Competenza del Dipartimento stesso.
Nella prima sezione vengono presentate
le attività di previsione, monitoraggio e
sorveglianza che svolge il Centro Funzionale
Decentrato della Regione Puglia nell’ambito
del sistema di allertamento. Nella seconda
sezione, relativa alle soglie pluviometriche,
dopo aver illustrato i differenti criteri di defi
nizione delle soglie di innesco di fenomeni
franosi e le fi nalità della loro applicazione,
vengono trattati i dati ed il metodo usato
per tentare di stabilire soglie per l’area del
Sub-Appennino Dauno, il settore a più elevata
suscettibilità da frane nella Regione Puglia.
Infi ne vengono discussi i risultati ottenuti e
riportate le conclusioni
Rainfall thresholds for the activation of shallow landslides in the Italian Alps: the role of environmental conditioning factors
No full textThe aim of the present work is to investigate the role exerted by selected environmental factors in the activation of rainfall-triggered shallow landslides and to identify site-specific rainfall thresholds. The study concerns the Italian Alps. The region is exposed to widespread slope instability phenomena due to its geological, morphological and climatic features. Furthermore, the high level of anthropization that characterizes wide portions of the territory increases the associated risk. Hence, the analysis of potential predisposing factors influencing landslides triggering is worthwhile to improve the current prediction skills and to enhance the preparedness and the response to these natural hazards.
During the last years, the Italian National Research Council’s Research Institute for Hydro-geological Protection (CNR-IRPI) has contributed to the analysis of triggering conditions for rainfall-induced landslides in the framework of a national project. The project, funded by the National Department for Civil Protection (DPC), focuses on the identification of the empirical rainfall thresholds for the activation of shallow landslides in Italy. The first outcomes of the project reveal a certain variability of the pluviometric conditions responsible for the mass movements activation, when different environmental settings are compared. This variability is probably related to the action of local environmental factors, such as lithology, climatic regime or soil characteristics. Based on this hypothesis, the present study aims to identify separated domains within the Italian Alps, where different triggering conditions exist and different countermeasures are needed for risk prevention. For this purpose, we collected information concerning 511 landslides activated in the period 2000-2012 and reconstructed 453 rainfall events supposed to be responsible for the activations. Then, we selected a set of thematic maps to represent the hypothesised landslide conditioning factors and to identify the supposed homogeneous domains within the study area. We employed an existing statistical method for the definition of the cumulated event rainfall vs. rainfall duration (ED) thresholds, for both the entire catalogue of rainfall events and for the events falling in the separated domains. The obtained results contribute to a better understanding of the role exerted by geological, pedological and climatic factors in landslides activation and help identifying separated domains where different risk managing strategies should be adopted. The proposed methodology can be a valid support for risk reduction strategies planning at regional scale
Extreme rainfall events in karst environments: the case study of September 2014 in the Gargano area (southern Italy)
No full textIn the first week of September 2014, the Gargano Promontory (Apulia, SE Italy) was hit by an extreme rainfall
event that caused several landslides, floods and sinkholes. As a consequence of the floods, two people lost their
lives and severe socio-economic damages were reported. The highest peaks of rainfall were recorded between
September 3rd and 6th at the Cagnano Varano and San Marco in Lamis rain gauges with a maximum daily rainfall
(over 230 mm) that is about 30% the mean annual rainfall.
The Gargano Promontory is characterized by complex orographic conditions, with the highest elevation of about
1000 m a.s.l. The geological setting consists of different types of carbonate deposits affected by intensive development
of karst processes. The morphological and climatic settings of the area, associated with frequent extreme
rainfall events can cause various types of geohazards (e.g., landslides, floods, sinkholes). A further element enhancing
the natural predisposition of the area to the occurrence of landslides, floods and sinkholes is an intense
human activity, characterized by an inappropriate land use and management.
In order to obtain consistent and reliable data on the effects produced by the storm, a systematic collection of information
through field observations, a critical analysis of newspaper articles and web-news, and a co-operation with
the Regional Civil Protection and local geologists started immediately after the event. The information collected
has been organized in a database including the location, the occurrence time and the type of geohazard documented
with photographs.
The September 2014 extreme rainfall event in the Gargano Promontory was also analyzed to validate the forecasts
issued by the Italian national early-warning system for rainfall-induced landslides (SANF), developed by the Research
Institute for Geo-Hydrological Protection (IRPI) for the Italian national Department for Civil Protection
(DPC). SANF compares rainfall measurements and forecasts with empirical rainfall thresholds for the prediction
of landslide occurrence. SANF forecasts were compared to the documented landslides and discussed
Rainfall events able to trigger shallow landslides in Calabria (Southern Italy).
No full textIn Calabria, la disponibilità di oltre 45000 eventi piovosi a scala di
tempo di cinque minuti ha permesso di precisare la struttura temporale
e la distribuzione spaziale, da assumere come input per i modelli
completi di versante. Lo studio è stato condotto proponendo un
semplice ed efficace metodo di classificazione automatica dei profili
di pioggia
