Abstract. Numerical simulation of seismoacoustic emission (SAE) associated with fracturing in zones of shear stress concentration shows that SAE signals are polarized along the stress direction. The proposed polarization methodology for monitoring of slope stability makes use of three-component recording of the microseismic field on a slope in order to pick the signals of slope processes by filtering and polarization analysis. Slope activity is indicated by rather strong roughly horizontal polarization of the respective portion of the field in the direction of slope dip. The methodology was tested in microseismic observations on a landslide slope in the Northern Tien-Shan (Kyrgyzstan).
53 Pags.- 16 Figs. The definitive version is available at: http://ascelibrary.org/journal/jhend8 ; Fast flows and avalanches of rock and debris are among the most dangerous of all landslide processes. Understanding and predicting postfailure motion (runout) of this kind of flowlike landslides is thus key for risk assessment, justifying the development of numerical models able to simulate their dynamics. In this paper a numerical method for the resolution of the depth-averaged debris flow model is presented. This set of nonlinear differential equations is formed by a variation of the shallow water equations, including strong bed slope, and a rheology resistance term. This paper focus on the numerical discretization of the resistance term, exploring three different approximations: pointwise, implicit, and unified. Well balance between numerical flux and source terms is only achieved using the unified discretization. In order to avoid nonphysical values of the water depth and discharge, a limitation of the unified resistance term is also needed. This correction is made following three conditions that identify the physical boundaries of the resistance term in the debris flow. This technique does not affect the computational efficiency of the method, keeping the original time step. Furthermore, proposed analytical test cases show that the three resistance limitations do not significantly perturb the numerical solution. The properties of the resulting numerical scheme are studied using a set of numerical experiments that include steady and transient flows. The results show the convenience of the unified discretization and the need of the three-condition limitation in order to avoid unphysical solutions. ; This research was supported by project Changing RISKS(OPE00446/PIM2010ECR-54900726)financed by EU FP7 ERANET CIRCLE Programme,and Grupo de Excelencia E68550 financed by the Aragón Government and the European Social Fund(ESF). ; CIRCLE Project reference:SSA-011793 ; Peer reviewed
This research represents outcrops of rocks at Cliffs of Tigris river ( Terraces ), most are Conglomerate, Sandstone, Siltstone and Clay stone. The research covers several aspects ; it includes a collection of field information from unstable rock slopes at (6) stations representing all the rock failure types that happened or likely to happen . In each station rock slopes are completely surveyed ; also the rocks are described in an engineering way and a complete discontinuity survey is carried out according to Anon (1972,1977) and their relationship with the rock failure is established. The field study shows that rock failures include toppling (mostly insecondary type ), rock fall. Point load test shows that Compressive Strength of the rock,( very weak – strong, σC = 0.450 – 51.480 )Mpa.
Abstract. A landslide hazard zonation is a division of the land surface into areas, and the relative ranking of these areas according to degrees of actual or potential hazard from landslides on slopes. Zonation from scientific research does not generally imply legal restrictions, but can be useful to those people who are charged with the land management, by providing them with information that is indispensable for planning and regulation purposes. This paper presents a zonation of rock slopes in carbonate mountains on the boundary to the east of the valley of the Sele River (Campania, southern Apennines of Italy). The mountains are severely affected by rock falls and topples, and the related hazard is, therefore, very high; the presence of inhabited areas (the towns of Valva, Colliano and Collianello) and other human infrastructures at the slope foothills make these phenomena extremely dangerous to the anthropogenic environment. The area is highly seismic, as experienced on the occasion of several moderate to strong earthquakes that have hit this sector of the Apennines. According to the zonation proposed here, the ridge of Mount Valva and Mount Marzano is subdivided into four main areas on the basis of the processes which take place in the different sectors of the mountains: the source area, the talus slope, the rockfall shadow (where scattered outlying boulders are present), and the safe area (outside of the reach of fallen blocks). The four sectors were identified through air-photo interpretation and detailed field surveys, aimed in particular at characterizing and interpreting the main rock mass joint patterns, and their relative orientation with respect to the local slope direction. Geological, morphological and structural analyses permitted one to evaluate and classify those parts of the slope that are more susceptible to detachment of rocks, and to identify the more diffuse types of failure. Due to high seismicity of the study area, particular attention was given to the evaluation of the seismic susceptibility to rock falls, by applying two methods recently proposed in literature. Results from this phase of the study were then integrated by additional information from historical research on slope movements occurred previously in the area. The landslide hazard zonation, shown on large-scale cartography, could be compared to maps depicting the distribution and typology of the anthropogenic activities, and thus constitutes a useful tool for administrators and planners, in order to evaluate the hazards related to slope movements, and the vulnerability of settlements, roads, and other man-made infrastructures.
AbstractEarly warning indicators often suffer from the shortness and coarse-graining of real-world time series. Furthermore, the typically strong and correlated noise contributions in real applications are severe drawbacks for statistical measures. Even under favourable simulation conditions the measures are of limited capacity due to their qualitative nature and sometimes ambiguous trend-to-noise ratio. In order to solve these shortcomings, we analyze the stability of the system via the slope of the deterministic term of a Langevin equation, which is hypothesized to underlie the system dynamics close to the fixed point. The open-source available method is applied to a previously studied seasonal ecological model under noise levels and correlation scenarios commonly observed in real world data. We compare the results to autocorrelation, standard deviation, skewness, and kurtosis as leading indicator candidates by a Bayesian model comparison with a linear and a constant model. We show that the slope of the deterministic term is a promising alternative due to its quantitative nature and high robustness against noise levels and types. The commonly computed indicators apart from the autocorrelation with deseasonalization fail to provide reliable insights into the stability of the system in contrast to a previously performed study in which the standard deviation was found to perform best. In addition, we discuss the significant influence of the seasonal nature of the data to the robust computation of the various indicators, before we determine approximately the minimal amount of data per time window that leads to significant trends for the drift slope estimations.
This study examines the behavior of three tests for significant slope variance in multilevel random coefficient (MRC) models: the Hierarchical Linear Modeling chi-square test, the likelihood ratio test (LRT), and the corrected LRT. Monte Carlo simulations are conducted varying the numbers of groups, group size, and effect size. Results suggest that neither the number of groups nor group size influenced Type I errors. Group size has a stronger effect on power compared with the number of groups. The one-tailed LRT demonstrates the best balance between power and Type I errors. Recommendations for conducting MRC analyses are presented.
Effective flood assessment and management depend on accurate models of flood events, which in turn are strongly affected by the quality of digital elevation models (DEMs). In this study, HEC-RAS was used to route one specificwater discharge through the main channel of the Eskilstuna River, Sweden. DEMs with various resolutions and accuracies were used to model the inundation. The results showed a strong positive relationship between the quality of theDEMand the extent of the inundation. However, evenDEMswith the highest resolution produced inaccuracies. In another case study, the Testebo River, the model settings could be calibrated, thanks to a surveyed old inundation event. However, even with the calibration efforts, the resulting inundation extents showed varying degrees of deviation from the surveyed flood boundaries. Therefore, it becomes clear that not only does the resolution of the DEM impact the quality of the results; also, the floodplain slope perpendicular to the river flow will impact the modelling accuracy. Flatter areas exhibited the greatest predictive uncertainties regardless of the DEM's resolution. For perfectly flat areas, uncertainty becomes infinite. ; Partly financed by the European Union through Swedish Agency for Economic and Regional Growth (Tillväxtverket) (project number 151092). ; DaGIS, GLOBES ; Kvalitetsbeskrivning av geografisk information vid översvämningskartering
Prior to the 1990s only few geological investigations of the seabed and the shallow geology around the Faroe Islands had been undertaken (Waagstein & Rasmussen 1975; Nielsen et al. 1981). However, in the 1990s marine geological and in particular seismic investigations were markedly intensified. Since 1993 several studies on the structure of the Faroe Islands margin and seafloor processes have been funded by the European Union, namely the ENAM (European North Atlantic Margin) project I and II (1993–1999) and the STRATAGEM (Stratigraphy of the Glaciated European Margin) project (2000–2003), and these have provided significant new information on the mechanisms shaping the Faroe Islands margin (e.g. Boldreel et al. 1998; Kuijpers et al. 1998a; Nielsen & van Weering 1998; van Weering et al. 1998). Due to the expertise and regional geological knowledge obtained during these projects the Geological Survey of Denmark and Greenland (GEUS) became involved in socalled 'geohazard' seabed studies of the Faroe–Shetland Channel in 1997. These investigations were financed by the petroleum industry that had begun to show significant interest in exploration of the Faroe–Shetland Channel area. The studies focused on possible natural risks that would affect submarine structures, such as slope instability and strong bottom currents, and included both shallow seismic data acquisition and sediment core analyses. Most of the work at sea was undertaken with the Russian research vessel Prof. Logachev, and carried out within the framework of the international, UNESCO-supported 'Training-Through-Research' (TTR) programme co-ordinated by Moscow State University, Russia. Since 1997, more than three million DKK have been granted for various projects and this work has been documented in 14 classified reports. This paper presents some of the main results from these 'geohazard' studies, in particular with respect to the sediment instability affecting the western flank of the Faroe–Shetland Channel, the occurrence of very strong bottom currents in the channel, and the newly discovered mud diapirs at the northern entrance of the channel (Fig. 1).
Over the second half of the 20th century, Greek governments failed to tax business income in line with the country's level of economic development. This paper uses the "slippery slope" model of tax compliance to explain why the reform of income and corporate taxation in the late 1950s met strong resistance in the business sector. We argue that the negative legacy of interwar reforms, the lack of sustained and credible investment in trust building in coincidence with the postwar reforms, and the intensification of coercive threats in tax enforcement led to an antagonistic tax climate and a degradation of enforced and voluntary compliance. Our qualitative analysis based on original primary sources shows that the arguments publicly voiced by entrepreneurs and their organizations reflected their persistent perception of tax power as unfair, arbitrary and extractive. Using aggregate tax returns data, our quantitative analysis finds evidence of systematic and increasing income underreporting both by unincorporated and incorporated businesses. This vicious circle of non-cooperation and mutual distrust explains why governments got trapped into a persistent low tax capacity equilibrium that still casts a shadow on the Greek economy.
This article addresses the impact of economic climate, and particularly of the Great Recession, on the configuration of educational expectations among students around 14 years old. We analyze expectations regarding educational attainment conditional on school performance and compare our results across countries with varying levels of economic growth over time. We expect a changing economic environment to impact on (a) the average level of educational expectations, (b) the association between social background and expectations, and (c) the association between school grades and expectations. Using pooled data from TIMSS for the years 2003, 2007 and 2011 among 8th graders for 24 developed countries, we estimate a set of country-fixed effects and hierarchical random-slope linear regression models. Most notably, our results indicate that economic down times depress educational expectations, especially among average-performing students, and lead to a growth in educational inequalities by family background.
AbstractThis article addresses the impact of economic climate, and particularly of the Great Recession, on the configuration of educational expectations among students around 14 years old. We analyze expectations regarding educational attainment conditional on school performance and compare our results across countries with varying levels of economic growth over time. We expect a changing economic environment to impact on (a) the average level of educational expectations, (b) the association between social background and expectations, and (c) the association between school grades and expectations. Using pooled data from TIMSS for the years 2003, 2007 and 2011 among 8th graders for 24 developed countries, we estimate a set of country-fixed effects and hierarchical random-slope linear regression models. Most notably, our results indicate that economic down times depress educational expectations, especially among average-performing students, and lead to a growth in educational inequalities by family background.
The phenomenon that occurred during the blizzard from February 5-6 in the mountains and especially on the southern slopes of the Southern Carpathians, is known in the literature as "strong downslope winds". This phenomenon occurred in a typical blizzard configuration, in which the differentiated advection of temperature led to the formation of a very stable air layer, with thermal inversion approximately between the levels of 850 and 700 hPa; and it also contributed in this layer to the change of wind direction to vertical. Thus, the existence in the same air layer of two factors favorable to the formation of a critical level, created the ideal conditions for generating strong downslope winds.
