stability of the sector is not an issue in the present state, and the hazard level should be low. Here, we highlight the diffi- culty of assessing the temporal probability on a specific site. Moreover, the statistical analysis showed a high dispersion in the rockfallhazardassessment for the a priori assessment, especially for the students and researchers, explained by their inexperience in this type of exercise. This result, coupled with the previous one, highlights the “plus-value” of the ex- perts: they do not overestimate the level of rockfallhazard in complex cases, and their assessment is more homogeneous and based on similar cases they have already studied due to their experience. Indeed, for sector 1, which exhibits the above mentioned pluri-decametric fracture, the results show a higher ratio of low-rockfallhazard levels for the experts. This suggests that the experts link the rockfallhazard assess- ment to the temporal probability assessment. For them, there is no risk of failure within a short time.
Abstract. Rockfallhazardassessment is not simple to achieve in practice and sound, physically based assessment methodologies are still missing. The mobility of rockfalls implies a more difficult hazard definition with respect to other slope instabilities with minimal runout. Rockfall haz- ard assessment involves complex definitions for “occurrence probability” and “intensity”. This paper is an attempt to eval- uate rockfallhazard using the results of 3-D numerical mod- elling on a topography described by a DEM. Maps portray- ing the maximum frequency of passages, velocity and height of blocks at each model cell, are easily combined in a GIS in order to produce physically based rockfallhazard maps. Different methods are suggested and discussed for rockfallhazard mapping at a regional and local scale both along lin- ear features or within exposed areas. An objective approach based on three-dimensional matrixes providing both a posi- tional “RockfallHazard Index” and a “RockfallHazard Vec- tor” is presented. The opportunity of combining different parameters in the 3-D matrixes has been evaluated to bet- ter express the relative increase in hazard. Furthermore, the sensitivity of the hazard index with respect to the included variables and their combinations is preliminarily discussed in order to constrain as objective as possible assessment cri- teria.
Discrete rockfall boulder runout events on the loessial soil slopes of the Port Hills, Christchurch, are affected by varia- tions in soil moisture content (e.g. Carey et al., 2017), which can cause soil hardness to dramatically change their effect on rockfall runout. Constraining rockfall modelling parameters to better reflect actual rockfall behaviour requires character- ization of soil hardness changes due to moisture content. In this paper, we analyse the results from two recorded rockfall events on loessial slopes in the Port Hills, Rapaki Bay and Mt Vernon. Both sites have similar substrate material, slope gradient, roughness, aspect, and density of vegetation. The three-dimensional rockfall model RAMMS was calibrated to a rockfall event (comprising the fall of multiple rocks) that occurred in dry conditions (Borella et al., 2016). The cali- brated model was then tested by forecasting rockfall runout on a different slope when the loessial soil was wet. This was done to provide a data set and methodology for practitioners to apply when carrying out rockfallhazard and risk assess- ments under both wet and dry soil conditions.
Several rockfall phenomena have affected the whole terri- tory of Castelmola, including the slopes impending over TR. Information on some of these landslides is available in the national databases of AVI (Italian Areas of Vulnerability; AVI Project, 1998) and P.A.I. (Piano stralcio per l’Assetto Idrogeologico, 2006). In 1952, the local daily newspaper La Gazzetta del Sud published an article on landslide move- ments occurring after heavy rain along the “only way of ac- cess to Castelmola”. More recently, the main documented events, which interrupted TR near the access to the village, occurred in 1996, 1997 and 1999, when rockfalls from the northern cliff (Fig. 3), involving a significant volume of rock, occurred (Ferrara and Pappalardo, 2005). With respect to the 1999 event, the AVI database reports that a falling boulder involved a car, while no victims were reported. After these episodes, the northern cliff was consolidated by means of deep anchors, concrete retaining structures and drainage gul- lies at the base of the slope (Fig. 3).
Rockfall is a major problem in high hill slopes and rocky mountainous regions and construction of highways at these rockfall prone areas often require stable slopes. The causes of rockfall are presence of discontinuities, high angle cut slopes, heavy rainfall, and unplanned slope geometry etc. Slope geometry is one of the most triggering parameters for rockfall, when there are variations in slope angle along the profile of slope. The Present study involves rockfallhazardassessment of road cut slopes for 15 km distance starting from Mahabaleshwar town along State Highway-72 (SH-72). The vertical to sub-vertical cut slopes are prone to instability due to unfavorable orientation of discontinuities in slope face of weathered and altered basaltic rockmass. The predominant type of instability has been found as wedge type fail- ure involving medium to large size blocks. In order to investigate the existing stability conditions, analyses were carried out at two locations under different slope conditions. The kinematic analysis was performed using stereographic pro- jection method. RockFall 4.0 numerical simulator software was used to calculate the maximum bounce heights, total kinetic energies and translational velocities of the falling rockmass blocks, and a comparative analysis is presented with increasing the mass of blocks and height of the slope. The result of numerical analysis shows that varying slope angle geometry creates more problems as compared to the mass of blocks in the scenario of rockfall.
Abstract— Floods are one of the most common hazards in the world and cause loss of lives, livelihood and property destruction. The objective of this study was to review and synthesize concepts and techniques of flood hazard, vulnerability and risk assessment with reference to the Himalayan region. Flood risk is a function and a product of hazard and vulnerability. The impact of flood and flash flood (slow onset and rapid onset) events at a particular sitecan reflect key socioeconomic factors and environmental services, like number of people at risk, affect on ecological services and capability of human population for recovery. Risk assessment is important in making decisions, policies and managing floods. Using PRISMA methodology of literature review, 120 articles were retrieved using PubMed and Google Scholar database. 90 articles were included in the initial review. 30 articles were excluded from the review after reading the whole content because they did not match the objectives of the literature review and the inclusion criteria. Flood hazardassessment techniques are based on various parameters such as meteorological, hydrological and socioeconomic. There are four important steps in flood risk assessment such as characterizing the area, determining hazard level and intensity, assessing vulnerability and risk. Recently, advancement in GIS, remote sensing and hydraulic modeling technology has been extensively used in formulating models used for flood hazard calculation and risk analysis. The occurrence of floods in mountainous regions are now more common related to past and in the future, itseems more frequent due to global warming. Community based flood warning systems can go a long way in helping rural communities, as well as flood management agencies, to prepare for flash floods. The enhancement of community resilience through socioeconomic empowerment and strengthened adaptive capacity can play a vital role in flood disaster management.
The presented case study is a typical one for which the aforementioned information is not available. Nevertheless, we showed that advanced numerical modelling techniques can be used to set up a sound risk assessment procedure which can be enforced at different levels of detail depend- ing on the available data. We suggest that, when detailed data are available to establish site-specific, statistically sound magnitude-frequency relationships and vulnerability func- tions, reliable estimates of absolute values of total expected costs can be obtained and supported by sensitivity analyses. Otherwise, conservative assumptions on the relevant parame- ters (e.g. MCF power law exponent or total annual number of rockfall events) can be used, provided that the sensitivity of risk calculations to the assumptions made has been evaluated (Fig. 14). Much effort should then be spent in setting up high-resolution numerical models allowing for a reliable as- sessment of impact probability and empirically-derived vul- nerability. However, even when detailed data is not available nor can be collected in a time and cost-effective way, the sug- gested risk analysis procedure proved to be effective in order to compare different risk scenarios, allowing a meaningful evaluation of the technical performance of different mitiga- tion options.
Following the procedures outlined in the Methodology section, we calculate the hazard according to models 1 and 2 to produce hazard maps (Fig. 9). The hazard levels generally follow the spatial trends of the seismicity rates. At the 500- year return period (Fig. 9a, which is equivalent to 10% ex- ceedance level in 50 years), hazard levels greater than 0 : 1 g are observed along the plate boundaries: along the Red Sea rift, the Gulf of Aden, and the Afar depression. A band of slightly elevated hazard level of greater than 0 : 07 g extends toward the west and northwest of the Gulf of Aden and bends toward the northeast from Massawa to the Red Sea rift. This hazard level roughly follows the western and northern boun- daries of the Danakil microplate along the Alid-Bada line and through Massawa toward the Red Sea rift. The cities of Massawa and Bada fall within this band and Asmara (the capital city of Eritrea), Tio, and Asseb (a port city) are on the margins of this band. The hazard levels increase with increas- ing return periods but the spatial pattern remains similar.
ing are strong, landslides and rock-body collapse are prone to occur during rainfall. In rockfall, rocks roll downslope due to instability caused by gravity or exogenic action and come to rest at an obstacle or in the gentler part of the slope (Huang et al., 2007). Rockfall is widely distributed and oc- curs suddenly, posing a serious threat to life and property (Pantelidis, 2010). In response to frequent rockfall disas- ters in recent years, numerous scholars in China and abroad have conducted in-depth studies into the characteristics of rockfall movement through theoretical analysis, field inves- tigation, and numerical simulation. For example, Mignelli et al. (2014) applied a rockfall risk management approach to the road infrastructure network of the Regione Autonoma Valle D’Aosta in order to calculate the level of risk and the potential for its reduction by rockfall protection devices. A comparative analysis of road accidents in the Aosta Valley was then undertaken to verify the methodology. Asteriou and Tsiambaos (2016) examined the effects of rock shape by per- forming tests with spherical and cubic blocks, finding that spherical blocks show higher and more consistent coefficient of restitution (COR) values than cubic blocks. Prina Howald et al. (2017) evaluated the protective capacity of existing and newly proposed protection measures and considered the pos- sible reclassification of hazard as a function of the mitigation role played by the measure. Furthermore, numerical simu- lation software has been adopted to analyze the characteris- tics of rockfall movement. The ROCFALL 3.0 software has been adopted in dam construction, road construction, and the protection of historical places to calculate the velocity and locus of rockfall and avoid damage to the project (Topal et al., 2006; Koleini and Van Rooy, 2011; Saroglou et al.,
Risk assessment as a scientific framework is be- ing promoted in the international trade and the food safety arena by the World Trade Organisa- tion (Campos 1998), the OIE, the Codex Ali- mentarius Commission and the EU. These or- ganisations are recognising the need for good quality data input and are promoting MO&SS as data sources. For example, the EU has listed the need for monitoring systems in a recent res- olution for an antibiotic resistance strategy (Anonymous 1999d). Similarly, the OIE writes in the latest edition of the International Animal Health Code (1999b) that each country that plans to export animals or animal products needs to supply information on its MO&SSHY- PERLINK. This is necessary for the importing country to review the evidence for freedom from disease and to assess the related risk (Welte et al. 1998). The OIE has also developed standards for the surveillance of rinderpest and contagious bovine pleuropneumonia (http:// www.oie.int/Norms/a_surv.htm), and standards regarding other diseases are likely to follow. As MO&SS are to be used as data sources for risk assessments the quality of the data pro-
of lives, damage to property, environmental hazards, and traffic congestions among others. Urban floods typically stem from a complex combination of causes. The urban environment is subject to the same natural forces as the natural environment and the presence of urban settlements exacerbates the problem. However, a relationship does exist between urbanization and the risk of flooding. This therefore, form the thrust of the study in which, Ado-Ekiti, the capital city of Ekiti State, a metropolitan with rapid urbanization is being evaluated to understand flood risks in the capital. The aim of this study is to evaluate and map flood risk in using GIS techniques. Assess the extent and magnitude of flooding in the study area, elements at risk in the study area, and to integrate these elements in a GIS environment. The is increasing awareness in the importance of Disaster risk management is leading scholars and researchers to a growing demand for better approaches to risk identification and assessment. This study seeks therefore to understand the way which people living in flood-prone areas in an urban environment perceive and understand flooding which is a threat to their lives and properties. Understanding what knowledge, the people have about flood events, how it affects their socioeconomic situation and changes to their physical environment, which
ABSTRACT: Heavy metal pollution in soil has severe consequences on the sustainability of ecological equilibrium. This study emphasizes the effect of heavy metal contaminated soil on okra and eggplant grown in Sanganer and Mathuradaspura areas of Jaipur, Rajasthan, India. The human health risk assessment was done by estimating the transfer factor, daily intake rate, hazard quotient and hazard indices for some metals. The results of the study indicated that the soil of Mathuradaspura dumping ground had elevated concentration Fe, Cu, Zn, Cr in contrast to the soil of Sanganer industrial area where elevated concentration of Pb, Cd and Ni were found. The vegetables were found to have increased levels of heavy metals like Pb, Cd and Ni in the Sanganer and Cu, Zn and Ni in Mathuradaspura. The high level of pollution was indicated by the high levels of hazard index in both the sites.
Abstract. Probabilistic hazard assessments are a fundamen- tal tool for assessing the threats posed by hazards to com- munities and are important for underpinning evidence-based decision-making regarding risk mitigation activities. Indone- sia has been the focus of intense tsunami risk mitigation ef- forts following the 2004 Indian Ocean tsunami, but this has been largely concentrated on the Sunda Arc with little at- tention to other tsunami prone areas of the country such as eastern Indonesia. We present the first nationally consistent probabilistic tsunami hazardassessment (PTHA) for Indone- sia. This assessment produces time-independent forecasts of tsunami hazards at the coast using data from tsunami gener- ated by local, regional and distant earthquake sources. The methodology is based on the established monte carlo ap- proach to probabilistic seismic hazardassessment (PSHA) and has been adapted to tsunami. We account for sources of epistemic and aleatory uncertainty in the analysis through the use of logic trees and sampling probability density functions. For short return periods (100 years) the highest tsunami haz- ard is the west coast of Sumatra, south coast of Java and the north coast of Papua. For longer return periods (500–2500 years), the tsunami hazard is highest along the Sunda Arc, reflecting the larger maximum magnitudes. The annual prob- ability of experiencing a tsunami with a height of > 0.5 m at the coast is greater than 10 % for Sumatra, Java, the Sunda islands (Bali, Lombok, Flores, Sumba) and north Papua. The
Hungr et al. (1999) compiled a rockfall inventory over the previous four decades along the Canadian Pacific rail line and BC Highway 1 corridor from Vancouver to Kamloops. The CP line generally follows the same route as CN through- out this corridor but is located on the opposite bank of the Thompson and Fraser rivers. These historical records contain data for events where volume information was available and span magnitudes from 0.01 to 3000 m 3 with a noted under- sampling of events below 1 m 3 . While this inventory can not be directly compared to the inventory generated using TLS, due to the different sampling periods and variation in route of the railways and highways, the TLS analysis methods pro- vide a higher level of detail for rockfalls in the range of 0.01 to 1 m 3 compared to the historical inventory for this area. In addition to a higher level of detail for smaller volume ranges, the rockfall information gathered from lidar provides infor- mation on the location of rockfall source zones, which can be used to characterize the failure processes operating on the slope. This information is not available from historical records collected at the base of a slope.
Abstract. A comprehensive methodology to assess forest fire susceptibility, that uses variables of strong spatial corre- lation, is presented and applied for the Portuguese mainland. Our study is based on a thirty-year chronological series of burnt areas. The first twenty years (1975–1994) are used for statistical modelling, and the last ten (1995–2004) are used for the independent validation of results. The wildfire af- fected areas are crossed with a set of independent layers that are assumed to be relevant wildfire conditioning factors: ele- vation, slope, land cover, rainfall and temperature. Moreover, the wildfire recurring pattern is also considered, as a proxy variable expressing the influence of human action in wildfire occurrence. A sensitivity analysis is performed to evaluate the weight of each individual theme within the susceptibil- ity model. Validation of the wildfire susceptibility models is made through the computation of success rate and predic- tion rate curves. The results show that it is possible to have a good compromise between the number of variables within the model and the model predictive power. Additionally, it is shown that integration of climatic variables does not produce any relevant increase in the prediction capacity of wildfire susceptibility models. Finally, the prediction rate curves pro- duced by the independent cross validation are used to assess the probabilistic wildfire hazard at a scenario basis, for the complete mainland Portuguese territory.
the hypothesis of invariability of landslide depth along the distance travelled, can only establish a preliminary evalua- tion of landslide dam hazard (Figs. 11a, 12a, 13a, 14a). The maps constructed using 2-D numerical modeling (Fig. 11b, 12b, 13b, 14b) diverge from those created with dfwalk mod- eling because of the extension of the hazard zone, which is smaller (Table 2). This method should be applied to estab- lish a detailed final hazard analysis. In both cases, the re- sults obtained demonstrate that an accurate digital elevation
Semi-analytical tephra dispersal models assume that vol- canic particles are instantaneously released at time zero (e.g. TEPHRA, Bonadonna et al., 2005a; HAZMAP, Barberi et al., 1990; Macedonio et al., 2005; ASHFALL, Hurst and Turner, 1999). They are usually applied to relatively short-lived activity, such as subplinian and Plinian eruptions (Suzuki, 1983; Armienti et al., 1988; Hurst and Turner, 1999; Connor et al., 2001). Nevertheless, violent strombolian eruptions, such as the 2001 and 2002–2003 Etna eruptions, can last sev- eral days (Scollo et al., 2007; Andronico et al., 2008) and are significantly affected by wind variations (Bursik et al., 1992; Sparks et al., 1997). TEPHRA was hence modified to account for the variation in wind direction and speed with time in or- der to compile a comprehensive hazardassessment of WLL eruptions. In particular, a specific number of wind profiles, n, associated with a given eruption is determined by dividing the total eruption duration by the interval between available wind profiles (e.g. six hours for the atmospheric sounding data of the Italian Air Force (IAF) at Trapani Birgi, located in western Sicily and available at http://weather.uwyo.edu). For instance, if the total eruption duration is 84 h, the number of wind profiles n is 14. When the duration cannot be precisely divided by the time interval (6 h), the number of wind pro- files is approximated. The total erupted mass is then divided by n, and n eruptions of a mass of M/n are sequentially run assuming constant eruptive parameters (i.e. H , TGSD, DL and DP, PR, K, FTT). The fraction m i,j of particles with size
Originally the plant was not designed for earthquake since the site seismic hazard was underestimated and the former Soviet design requirements did not require specific design measures for this case. Early nineties the site seismic hazard has been re-evaluated using comprehensive probabilistic seismic hazardassessment (PSHA) methodology, Tóth, Győri and Katona (2009), new seismic design basis has been defined with peak ground acceleration (PGA) 0,25 g for 10 -4 /a non-exceedance level.
form with a uniform and consistent georeferencing scheme. A broad framework is depicted in Fig. 1. The scheme out- lines compilation of information related to seismicity, identi- fication of potential seismic source zones, development of seismicity models, and maximum earthquake prognosis in the regional level supported by earthquake catalogues and other relevant data such as fault database. The local level assessments involve mapping of surficial geological and geo- morphological features supported by 2/3 D sub-surface mod- els, and development of geotechnical database, and evalua- tion of different surficial soil attributes (e.g. density, rigid- ity, compressibility, damping, water content, etc.), and base- ment topography. The prevalent seismic characteristics, in terms of predominant frequency, site response, path and source attributes, are generally established through analytical and numerical treatment of the waveform, micro-tremor and geotechnical data, and thereupon, deterministic assessment is carried out by means of strong ground motion simulations. Additional evaluations include that of relevant earthquake in- duced effects such as soil liquefaction and landslides. Even- tually, a composite assessment is taken up of the geologi- cal, geotechnical, and seismological attributes to deliver the seismic microzonation in terms of a hazard index map. A microzonation project can be viewed into three levels in or- der of the mapping resolution, precision, data volume and complexity of the problems (Bard et al., 1995). The elemen- tary level comprises of compilation of available data deliver- ing zonation in the scale of 1:25 000 to 1:10 000. The next level is achieved with specific surveys that include drilling, trenching, geophysical data acquisition, etc with comprehen- sive analysis/synthesis. The third highest level involves enor- mous volume of data compilation from a larger number of in- vestigation points, enhanced techniques and exhaustive data processing to deliver the high resolution hazard maps in the scales of 1:10 000 or 1:5 000.