Papers by paola reichenbach
Journal of Maps
The island of Gran Canaria (Canary Islands, Spain) is characterized by a large variability of vol... more The island of Gran Canaria (Canary Islands, Spain) is characterized by a large variability of volcanic rocks reflecting its volcanic evolution. The geological map provided by Geological Survey of Spain at 1:25.000 scale shows more than 109 different lithologies and it is too complex for environmental and engineering purposes. This work presents a simplified geotechnical map with a small number of classes grouping up units with similar geotechnical behaviours. The lithologies were grouped using about 350 rock samples, collected in the seven major islands of the Archipelago. The geotechnical map was used to model rockfall hazard in the entire island of Gran Canaria, where rockfalls are an important threat. The rockfall map was validated with 128 rockfall events along the GC-200 road, located in the NW sector of Gran Canaria. About 96% of the events occurred along sections of the road where the number of expected trajectories is high or moderate.
Journal of Maps, 2020
The island of Gran Canaria (Canary Islands, Spain) is characterized by a large variability of vol... more The island of Gran Canaria (Canary Islands, Spain) is characterized by a large variability of volcanic rocks reflecting its volcanic evolution. The geological map provided by Geological Survey of Spain at 1:25.000 scale shows more than 109 different lithologies and it is too complex for environmental and engineering purposes. This work presents a simplified geotechnical map with a small number of classes grouping up units with similar geotechnical behaviours. The lithologies were grouped using about 350 rock samples, collected in the seven major islands of the Archipelago. The geotechnical map was used to model rockfall hazard in the entire island of Gran Canaria, where rockfalls are an important threat. The rockfall map was validated with 128 rockfall events along the GC-200 road, located in the NW sector of Gran Canaria. About 96% of the events occurred along sections of the road where the number of expected trajectories is high or moderate. ARTICLE HISTORY
Natural Hazards and Earth System Sciences, 2019
The use of remotely piloted aircraft systems (RPASs) in geosciences is often aimed at the acquisi... more The use of remotely piloted aircraft systems (RPASs) in geosciences is often aimed at the acquisition of an image sequence to produce digital models and orthopho-tographs of the topographic surface. The technology can be applied for rockfall hazard and risk assessment. To study rockfalls, an approach consists in the application of numerical models for the computation of rockfall trajectories. Data required for such simulations include digital terrain models, location of the instability source areas, and the mechanical properties of the terrain. In this article, we present an analysis of the earthquake-triggered rockfall that occurred along the SP18 in Villanova di Accumoli (Lazio, central Italy) during the seismic sequence that started on 24 August 2016. A survey with a multicopter was carried out to obtain a surface model of the terrain and identify and characterize the source areas and other instable blocks in areas not accessible in the field. The investigated area extends for 6500 m 2 and was covered by 161 photographs that were used to obtain an orthophoto with a ground resolution of 2.5 cm and a digital surface model with a ground resolution of 20 cm × 20 cm, which was processed and fused with GNSS real-time kine-matic data. To obtain a map of potential rockfall trajecto-ries, we run the numerical model STONE, using as origin of the boulders both source areas mapped in the field and pixels with a slope angle above a selected threshold. Results showed that only the part of the road SP18 already affected by the rockfall was exposed to further rockfall impacts. In particular, it was observed that 29.2 % (i.e. 12 123) of the 41 500 simulated trajectories may potentially reach or cross this tract of the road. Based on these data, limited protection measures were suggested. The combined use of RPAS data, fused with ground GPS points, an accurate geomorpholog-ical survey, and terrain static and dynamic parameters from the literature allows fast, low-cost, and replicable rockfall numerical modelling useful for emergency response and adoption of proper protection measures.
ABSTRACT We focused on the joint exploitation of satellite and ground-based technologies in order... more ABSTRACT We focused on the joint exploitation of satellite and ground-based technologies in order to understand the kinematic behavior of landslides and subsidence phenomena relevant to different test sites in Europe. In this context, we efficiently exploited C-band and X-band satellite and ground-based SAR data for the investigation of the temporal and spatial pattern of ground deformations caused by natural and human-induced hazards. The present work has been conducted within the FP7-EU DORIS project.
On 1 October 2009, a high intensity storm hit the Ionian coast of Sicily, SW of Messina, Italy. T... more On 1 October 2009, a high intensity storm hit the Ionian coast of Sicily, SW of Messina, Italy. The Santo Stefano di Briga rain gauge, located 2 km W of the Ionian coast, recorded 225 mm of rain in seven hours. The intense rainfall event triggered abundant slope failures, and resulted in widespread erosion and deposition of debris along ephemeral drainage channels, extensive inundation, and local modifications of the coastline. Landslides occurred in a territory prone to slope failures, due to the local geological and geomorphological settings. Many landslides were related to the presence of roads lacking adequate drainage. Abandoned terraced slopes lacking proper drainage, and unmaintained dry walls were also related to slope failures. Damage was particularly severe in small villages and at several sites along the transportation network. The shallow landslides and the inundation resulted in 37 fatalities, including 31 deaths and six missing persons, and innumerable injured people. After the event, an accurate landslide inventory map was prepared for the Briga and the Giampilieri catchments. The map shows: (i) the distribution of the event landslides triggered by the 1 October 2009 rainfall event; (ii) the distribution of the pre-existing slope failures; and (iii) other geomorphological features related to fluvial processes and slope movements. The landslide inventory map was prepared at 1:10,000 scale through a combination of field surveys and photo-interpretation of pre-event and post-event, stereoscopic and pseudo-stereoscopic, aerial photography. Different types of aerial photographs were analysed visually to prepare the landslide inventory map. The event landslides were mapped through the interpretation of pseudo-stereoscopic colour photographs taken shortly after the event at 1:3500 scale, combined with digital stereoscopic photographs at approximately 1:4500 scale, taken in November 2009. The pre-event landslides and the associated geomorphological features were mapped using 1:33,000 scale aerial photographs flown in 1954, 1955, and 2005. The event and pre-existing landslides were checked in the field in the period October–November 2009.
Landslides, 2013
ABSTRACT In the framework of the European Soil Thematic Strategy and the associated proposal of a... more ABSTRACT In the framework of the European Soil Thematic Strategy and the associated proposal of a Framework Directive on the protection and sustainable use of soil, landslides were recognised as a soil threat requiring specific strategies for priority area identification, spatial hazard assessment and management. This contribution outlines the general specifications for nested, Tier-based geographical landslide zonings at small spatial scales to identify priority areas susceptible to landslides (Tier 1) and to perform quantitative susceptibility evaluations within these (Tier 2). A heuristic, synoptic-scale Tier 1 assessment exploiting a reduced set of geoenvironmental factors derived from common pan-European data sources is proposed for the European Union and adjacent countries. Evaluation of the susceptibility estimate with national-level landslide inventory data suggests that a zonation of Europe according to, e.g. morphology and climate, and performing separate susceptibility assessments per zone could give more reliable results. To improve the Tier 1 assessment, a geomorphological terrain zoning and landslide typology differentiation are then applied for France. A multivariate landslide susceptibility assessment using additional information on landslide conditioning and triggering factors, together with a historical catalogue of landslides, is proposed for Tier 2 analysis. An approach is tested for priority areas in Italy using small administrative mapping units, allowing for relating socioeconomic census data with landslide susceptibility, which is mandatory for decision making regarding the adoption of landslide prevention and mitigation measures. The paper concludes with recommendations on further work to harmonise European landslide susceptibility assessments in the context of the European Soil Thematic Strategy.
In the paper we analyse a multi-date landslide inventory prepared for a mountainous area affected... more In the paper we analyse a multi-date landslide inventory prepared for a mountainous area affected by several landslide types with different degrees of activity, we attempt to quantify the uncertainties associated to the mapping, we measure the evolution of morphological indicators and estimate landslide activity and temporal occurrence. The inventory, covering the period 1956–2010, is prepared for the middle section of the Ubaye valley (southern French Alps) based on the analysis of multi-source documents (geomorphological maps, historical reports of landslide events, field surveys, orthophotographs and SAR (synthetic aperture radar) satellite images). The uncertainties derived from the expert interpretation of different sources of information, the landslide morphological features and the affected land covers are taken into account in relation to the source documents.
Morphological indicators are calculated to describe quan- titatively the evolution of the landslides (length, area, relative elevation, runout distance). Frequency–area density functions are computed to estimate the changes in the landslide distributions and a Poisson model is used to estimate the probability of reactivation of the observed landslides and the occurrence of new failures. The proposed multi-date inventory and the associated statistics provide additional information to the event catalogue managed by the local policy makers.
In Italy, severe meteorologically induced geo-hydrological events are characterized by a complex ... more In Italy, severe meteorologically induced geo-hydrological events are characterized by a complex combination of landslides and floods, and may cause casualties and damage to urban areas and the utility network. On 1 October 2009, a high intensity rainstorm in the Messina area, Sicily, triggered more than 500 shallow landslides in an area of about 60 km2, mostly in the soils mantling the metamorphic and crystalline bedrock of the Peloritan Arc. The high intensity rainfall further resulted in massive erosion and deposition of debris along the ephemeral drainage channels, widespread inundation, and local modification of the coastline. Damage was particularly severe in the several small villages present in the area, including Giampilieri, Scaletta Zanclea, Guidomandri, Pèzzolo, Altolìa, and Itàla. Damage to the transportation network was also severe and widespread. The several rainfall-induced landslides and the inundations have resulted in 31 deaths, 6 missing persons, numerous injured persons, and more than 2500 evacuated and homeless people. In the aftermath of the event, we: (i) completed a preliminary field survey in the area most affected by landslides and inundations, documenting the ground effects of the intense rainfall, (ii) acquired satellite imagery, including very-high-resolution optical images taken by QuickBird and high-resolution radar images taken by COSMO-SkyMed, and (iii) acquired stereoscopic aerial photography, including pre-event aerial photographs taken in 1954, 1995, and 2005, and post event, very-large scale images taken by helicopter immediately after the event. In this work, we present preliminary results of the exploitation of multiple remote-sensing technologies and information for the identification, mapping and classification of the rainfall induced landslides, and of the eroded and the inundated areas. Emphasis is given to the critical analysis of the capacity and limits of the available airborne and satellite remote sensing technologies for the rapid mapping of geo-hydrological events, and the associated damage.
Natural Hazards and Earth System Sciences, 2002
We present a geomorphological method to evaluate landslide hazard and risk. The method is based o... more We present a geomorphological method to evaluate landslide hazard and risk. The method is based on the recognition of existing and past landslides, on the scrutiny of the local geological and morphological setting, and on the study of site-specific and historical information on past landslide events. For each study area a multi-temporal landslide inventory map has been prepared through the interpretation of various sets of stereoscopic aerial photographs taken over the period 1941-1999, field mapping carried out in the years 2000 and 2001, and the critical review of site-specific investigations completed to solve local instability problems. The multi-temporal landslide map portrays the distribution of the existing and past landslides and their observed changes over a period of about 60 years. Changes in the distribution and pattern of landslides allow one to infer the possible evolution of slopes, the most probable type of failures, and their expected frequency of occurrence and intensity. This information is used to evaluate landslide hazard, and to estimate the associated risk. The methodology is not straightforward and requires experienced geomorphologists, trained in the recognition and analysis of slope processes. Levels of landslide hazard and risk are expressed using an index that conveys, in a simple and compact format, information on the landslide frequency, the landslide intensity, and the likely damage caused by the expected failure. The methodology was tested in 79 towns, villages, and individual dwellings in the Umbria Region of central Italy.
Geomorphology, 1999
In recent years, growing population and expansion of settlements and life-lines over hazardous ar... more In recent years, growing population and expansion of settlements and life-lines over hazardous areas have largely increased the impact of natural disasters both in industrialized and developing countries. Third world countties have difficulty meeting the high costs of controlling natural hazards through major engineering works and rational land-use planning. Industrialized societies are increasingly reluctant to invest money in structural measures that can reduce natural risks. Hence, the new issue is to implement warning systems and land utilization regulations aimed at minimizing the loss of lives and property without investing in long-term, costly projects of ground stabilization. Government and research institutions worldwide have long attempted to assess landslide hazard and risks and to portray its spatial distribution in maps. Several different methods for assessing landslide hazard were proposed or implemented. The reliability of these maps and the criteria behind these hazard evaluations are ill-formalized or poorly documented. Geomorphological information remains largely descriptive and subjective. It is, hence, somewhat unsuitable to engineers, policy-makers or developers when planning land resources and mitigating the effects of geological hazards. In the Umbria and Marche Regions of Central Italy, attempts at testing the proficiency and limitations of multivariate statistical techniques and of different methodologies for dividing the territory into suitable areas for landslide hazard assessment have been completed, or are in progress, at various scales. These experiments showed that, despite the operational and conceptual limitations, landslide hazard assessment may indeed constitute a suitable, cost-effective aid to land-use planning. Within this framework, engineering geomorphology may playa renewed role in assessing areas at high landslide hazard, and helping mitigate the associated risk. (F. Guzzetti). and approximately 45% of it is concentrated in urban areas. The most explosive growth has been in the developing world, where urban populations have tripled in the last 30 years. Between 1950 and 1995, the number of cities with population of more than one million increased sixfold in the third world .
Geomorphology, 2006
We present a landslide susceptibility model for the Collazzone area, central Italy, and we propos... more We present a landslide susceptibility model for the Collazzone area, central Italy, and we propose a framework for evaluating the model reliability and prediction skill. The landslide susceptibility model was obtained through discriminant analysis of 46 thematic environmental variables and using the presence of shallow landslides obtained from a multi-temporal inventory map as the dependent variable for statistical analysis. By comparing the number of correctly and incorrectly classified mapping units, it is established that the model classifies 77.0% of 894 mapping units correctly. Model fitting performance is investigated by comparing the proportion of the study area in each probability class with the corresponding proportion of landslide area. We then prepare an ensemble of 350 landslide susceptibility models using the same landslide and thematic information but different numbers of mapping units. This ensemble is exploited to investigate the model reliability, including the role of the thematic variables used to construct the model, and the model sensitivity to changes in the input data. By studying the variation of the model's susceptibility estimate, the error associated with the susceptibility assessment for each mapping unit is determined. This result is shown on a map that complements the landslide susceptibility map. Prediction skill of the susceptibility model is then estimated by comparing the forecast with two recent event inventory maps. The susceptibility model is found capable of predicting the newly triggered landslides. A general framework for testing a susceptibility model is proposed, including a scheme for ranking the quality of the susceptibility assessment.
Earth and Planetary Science Letters, 2004
This paper relates landslide inventories to erosion rates and provides quantitative estimates of ... more This paper relates landslide inventories to erosion rates and provides quantitative estimates of the landslide hazard associated with earthquakes. We do this by utilizing a three-parameter inverse-gamma distribution, which fits the frequencyarea statistics of three substantially dcompleteT landslide-event inventories. A consequence of this general distribution is that a landslide-event magnitude m L =logN LT can be introduced, where N LT is the total number of landslides associated with the landslide event. Using this general distribution, landslide-event magnitudes m L can be obtained from incomplete landslide inventories, and the total area and volume of associated landslides, as well as the area and volume of the maximum landslides, can be directly related to the landslide-event magnitude. Using estimated recurrence intervals for three landslide events and the time span for two historical inventories, we estimate regional erosion rates associated with landslides as typically 0.1-2.5 mm year À1 . We next give an empirical correlation between the earthquake magnitude, associated landslideevent magnitude, and the total volume of associated landslides. Using these correlations, we estimate that the minimum earthquake magnitudes that will generate landslides is M=4.3F0.4. Finally, using Gutenberg-Richter frequency-magnitude statistics for regional seismicity, we relate the intensity of seismicity in an area and the magnitude of the largest regional earthquakes to erosion rates. We find that typical seismically induced erosion rates in active subduction zones are 0.2-7 mm year À1 and adjacent to plate boundary strike-slip fault zones are 0.01-0.7 mm year À1 .
Geomorphology, 2005
We propose a probabilistic model to determine landslide hazard at the basin scale. The model pred... more We propose a probabilistic model to determine landslide hazard at the basin scale. The model predicts where landslides will occur, how frequently they will occur, and how large they will be. We test the model in the Staffora River basin, in the northern Apennines, Italy. For the study area, we prepare a multi-temporal inventory map through the interpretation of multiple sets of aerial photographs taken between 1955 and 1999. We partition the basin into 2243 geo-morpho-hydrological units, and obtain the probability of spatial occurrence of landslides by discriminant analysis of thematic variables, including morphological, lithological, structural and land use. For each mapping unit, we obtain the landslide recurrence by dividing the total number of landslide events inventoried in the unit by the time span of the investigated period. Assuming that landslide recurrence will remain the same in the future, and adopting a Poisson probability model, we determine the exceedance probability of having one or more landslides in each mapping unit, for different periods. We obtain the probability of landslide size by analysing the frequency-area statistics of landslides, obtained from the multi-temporal inventory map. Assuming independence, we obtain a quantitative estimate of landslide hazard for each mapping unit as the joint probability of landslide size, of landslide temporal occurrence and of landslide spatial occurrence. D
Natural Hazards and Earth System Sciences, 2003
Rock slides and rock falls are the most frequent types of slope movements in Yosemite National Pa... more Rock slides and rock falls are the most frequent types of slope movements in Yosemite National Park, California. In historical time 392 rock falls and rock slides have been documented in the valley, and some of them have been mapped in detail. We present the results of an attempt to assess rock fall hazards in the Yosemite Valley. Spatial and temporal aspects of rock falls hazard are considered. A detailed inventory of slope movements covering the 145-year period from 1857 to 2002 is used to determine the frequency-volume statistics of rock falls and to estimate the annual frequency of rock falls, providing the temporal component of rock fall hazard. The extent of the areas potentially subject to rock fall hazards in the Yosemite Valley were obtained using STONE, a physically-based rock fall simulation computer program. The software computes 3-dimensional rock fall trajectories starting from a digital elevation model (DEM), the location of rock fall release points, and maps of the dynamic rolling friction coefficient and of the coefficients of normal and tangential energy restitution. For each DEM cell the software calculates the number of rock falls passing through the cell, the maximum rock fall velocity and the maximum flying height. For the Yosemite Valley, a DEM with a ground resolution of 10×10 m was prepared using topographic contour lines from the U.S. Geological Survey 1:24 000-scale maps. Rock fall release points were identified as DEM cells having a slope steeper than 60 • , an assumption based on the location of historical rock falls. Maps of the normal and tangential energy restitution coefficients and of the rolling friction coefficient were produced from a surficial geologic map. The availability of historical rock falls mapped in detail allowed us to check the computer program performance and to calibrate the model parameters. Visual and statistical comparison of the model results with the mapped rock falls confirmed the accuracy of the model. The model results are compared with a previous map of rockfall talus and with a geomorphic assessment of rock fall hazard based on potential energy referred to as a shadow angle approach, Correspondence to: F. Guzzetti ([email protected]) recently completed for the Yosemite Valley. The model results are then used to identify the roads and trails more subject to rock fall hazard. Of the 166.5 km of roads and trails in the Yosemite Valley 31.2% were found to be potentially subject to rock fall hazard, of which 14% are subject to very high hazard.
Earth Surface Processes and Landforms, 2004
Landslides are generally associated with a trigger, such as an earthquake, a rapid snowmelt or a ... more Landslides are generally associated with a trigger, such as an earthquake, a rapid snowmelt or a large storm. The landslide event can include a single landslide or many thousands. The frequency-area (or volume) distribution of a landslide event quantifies the number of landslides that occur at different sizes. We examine three well-documented landslide events, from Italy, Guatemala and the USA, each with a different triggering mechanism, and find that the landslide areas for all three are well approximated by the same three-parameter inverse-gamma distribution. For small landslide areas this distribution has an exponential 'roll-over' and for medium and large landslide areas decays as a power-law with exponent −2·40. One implication of this landslide distribution is that the mean area of landslides in the distribution is independent of the size of the event. We also introduce a landslide-event magnitude scale m L = log(N LT ), with N LT the total number of landslides associated with a trigger. If a landslide-event inventory is incomplete (i.e. smaller landslides are not included), the partial inventory can be compared with our landslide probability distribution, and the corresponding landslide-event magnitude inferred. This technique can be applied to inventories of historical landslides, inferring the total number of landslides that occurred over geologic time, and how many of these have been erased by erosion, vegetation, and human activity. We have also considered three rockfall-dominated inventories, and find that the frequency-size distributions differ substantially from those associated with other landslide types. We suggest that our proposed frequency-size distribution for landslides (excluding rockfalls) will be useful in quantifying the severity of landslide events and the contribution of landslides to erosion.
Geomorphology, 2008
Landslide inventory maps are effective and easily understandable products for both experts, such ... more Landslide inventory maps are effective and easily understandable products for both experts, such as geomorphologists, and for non experts, including decision-makers, planners, and civil defense managers. Landslide inventories are essential to understand the evolution of landscapes, and to ascertain landslide susceptibility and hazard. Despite landslide maps being compiled every year in the word at different scales, limited efforts are made to critically compare landslide maps prepared using different techniques or by different investigators. Based on the experience gained in 20 years of landslide mapping in Italy, and on the limited literature on landslide inventory assessment, we propose a general framework for the quantitative comparison of landslide inventory maps. To test the proposed framework we exploit three inventory maps. The first map is a reconnaissance landslide inventory prepared for the Umbria region, in central Italy. The second map is a detailed geomorphological landslide map, also prepared for the Umbria region. The third map is a multi-temporal landslide inventory compiled for the Collazzone area, in central Umbria. Results of the experiment allow for establishing how well the individual inventories describe the location, type and abundance of landslides, to what extent the landslide maps can be used to determine the frequency-area statistics of the slope failures, and the significance of the inventory maps as predictors of landslide susceptibility. We further use the results obtained in the Collazzone area to estimate the quality and completeness of the two regional landslide inventory maps, and to outline general advantages and limitations of the techniques used to complete the inventories.
Earth Surface Processes and Landforms, 1991
Geographical Information Systems (GIS) and numerical cartography may greatly facilitate the devel... more Geographical Information Systems (GIS) and numerical cartography may greatly facilitate the development and use of statistical models for the assessment of regional landslide hazard.From a small drainage basin located in Central Italy, relevant geological and geomorphological factors were collected and processed by applying GIS technology. In particular, modules were used which both generate high-fidelity digital terrain models and automatically partition the terrain into main slope-units. The resulting information was then analysed by discriminant analysis which enabled landslide hazard and risk to be evaluated in each slope-unit. Although not lacking drawbacks, the method proved to be a feasible and cost-effective approach to landslide susceptibility assessment and mapping.
Geomorphology, 1994
The study has divided Italy into eight major topographic divisions (provinces) and 30 minor divis... more The study has divided Italy into eight major topographic divisions (provinces) and 30 minor divisions (sections) that are similar to N. Fenneman's units of the United States. Provinces and sections are generally consistent with observed morphology. The new units were defined step-wise in a semi-quantitative approach that combined an unsupervised three-class cluster analysis of four derivatives of altitude, visual interpretation of morphometric maps (including shaded relief), and comparative inspection of small-scale geological and structural maps. The four variables are altitude, slope curvature, frequency of slope reversal, and elevation-relief ratio. Highland, upland, and lowland topographic types were identified. The variables were computed from a 230 m resolution digital terrain model, regridded from the original 230 m DEM obtained by mosaicking the entire Italian mean elevation archive.
Geomorphology, 1997
Seventeen alluvial fans in the PO Plain, between the Ticino and Mincio Rivers, in Northern Italy ... more Seventeen alluvial fans in the PO Plain, between the Ticino and Mincio Rivers, in Northern Italy were identified and studied. The research was carried out following a semi-quantitative approach that combined display and analysis of altitude data, interpretation of morphometrical maps, and comparative inspection of geomorphological maps. Boundaries between fans were drawn interactively on a shaded relief image, computed from a 50 m resolution digital terrain model prepared interpolating 5 and 1 metre contour lines. For each fan, or for each portion making up a larger fan, geometric and morphometric criteria were computed. Fan morphometric criteria were compared to the present drainage basins morphological setting. The relationship between fan area and drainage basin area shows positive allometry, with the slope of the regression line lower than that commonly proposed for both arid and humid regions.
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Papers by paola reichenbach
Morphological indicators are calculated to describe quan- titatively the evolution of the landslides (length, area, relative elevation, runout distance). Frequency–area density functions are computed to estimate the changes in the landslide distributions and a Poisson model is used to estimate the probability of reactivation of the observed landslides and the occurrence of new failures. The proposed multi-date inventory and the associated statistics provide additional information to the event catalogue managed by the local policy makers.
Morphological indicators are calculated to describe quan- titatively the evolution of the landslides (length, area, relative elevation, runout distance). Frequency–area density functions are computed to estimate the changes in the landslide distributions and a Poisson model is used to estimate the probability of reactivation of the observed landslides and the occurrence of new failures. The proposed multi-date inventory and the associated statistics provide additional information to the event catalogue managed by the local policy makers.