Rainfall-induced shallow landslides in Northern Tuscany (Italy): geotechnical characterization and rainfall thresholds

In this preface we introduce the PhD Thesis on rainfall-induced landslides entitled “Rainfall-induced shallow landslides in Northern Tuscany (Italy): geotechnical characterization and rainfall thresholds”. Rainfall-induced landslides deserved a large interest in international literature in the last decades. The literature on this matter shows a markedly interdisciplinary approach, with contributions from different fields, such as engineering geology, soil mechanics, hydrology and geomorphology. The subject is of high interest for many practical and scientific reasons. In fact, rainfall is the most relevant factor for triggering shallow landslides, and rainfall analysis is the most frequently adopted approach in forecasting the occurrence of such phenomena. Moreover, the estimation of the properties of materials mainly involved by shallow landslides is fundamental in understanding their triggering mechanism. With the aim of contributing in studying the rainfall-induced shallow landslides in Northern Tuscany, different topics were considered: the analysis of the rainstorms of 2009-2010 period and of their consequences, the geotechnical characterization of the source areas of shallow landslides, and the determination of critical rainfall thresholds for triggering such phenomena. For these reasons, the manuscript was structured in three different but complementary papers. The papers are briefly introduced, examining their contribution in understanding of the rainfall-induced shallow landslides, as follows. The first paper “The 2009 and 2010 meteorological events in Northern Tuscany (Italy): Characteristics and effects on slope stability” describes characteristics and main effects on slope stability of the rainstorms which hit the Northern Tuscany in December 2009 (north-western Tuscany), June 2010 (Serchio River Valley) and October 2010 (Massa-Carrara province). The rainfall events were analyzed in terms of rainfall amount, intensity and duration. Moreover, the antecedent rainfall related to such events was analyzed, focusing on its role in causing instability conditions of slopes. The paper highlights again that the shallow landslides commonly occurred in peculiar geologic and geomorphologic environments: colluvium/debris thin slope cover, semi-permeable or impermeable bedrock, hollow shaped slope, high slope gradient. Moreover, it highlights that the shallow landslides in Northern Tuscany mainly involve the soils covering the arenaceous formations, such as the Macigno Fm. In this context, the second paper “Geotechnical characterization of source areas of shallow landslides by dynamic penetration tests in Northern Tuscany (Italy): first results and perspectives” aims at contributing to the characterization of the typical source areas of the shallow landslides in the Serchio River Valley, by means of dynamic penetration tests (Dynamic Probing, DP). In fact, these tools are particularly suitable to obtain geotechnical properties of the soils in difficult access slopes. Original data, coming from inspections of existing databases or expressly performed tests, are presented and discussed. Relative density and friction angle were determined processing the results of DP tests by means of empirical methods. Moreover, the soil properties obtained by DP tests were compared with those obtained by Standard Penetration Tests (SPT) and direct shear tests. The comparison suggests that the DP tests can be an effective tools in geotechnical characterization of potentially unstable soil slope covers. Finally, the last paper “Critical rainfall thresholds for triggering shallow landslides in the Serchio River Valley (Tuscany, Italy)” proposes the critical rainfall thresholds for triggering shallow landslides in Middle Serchio River Valley. The rainfall data recorded by three rain gauges in the 1935-2010 period were analyzed and compared with the occurrence of shallow landslides. The rainfall thresholds were defined in terms of mean intensity, rainfall duration and normalized using the mean annual precipitation. Some attempts were also carried out to analyze the role of rainfall prior to the damaging events. Moreover, the rainfall thresholds obtained for the study area were compared with the local, regional and global thresholds proposed by various authors. The results of these analysis suggest that in the Middle Serchio River Valley, and in general in Northern Tuscany, landslides activity initiation requires a higher amount of rainfall and greater intensity than elsewhere. At present, further research is necessary in order to reach a zonation of the shallow landslide hazard in the study area. The methodological approach used for the characterization of the source areas of the shallow landslides may be improved in several aspects (e.g. performing of direct shear tests on undisturbed soils, calibration of DP tests results and performing of empirical relations specifically calibrated on the considered soils). Other important parameters, such as slope gradient and soil thickness, may be considered. The critical rainfall thresholds obtained in this work may be tested and compared with those obtained by statistical or deterministic approaches. The evolution of this research is towards performing of susceptibility maps and comparison with rainfall thresholds for triggering shallow landslides. This is crucial for the preparation of landslide hazard maps and scenarios for different rainfall amounts in an area particularly prone to shallow landslides

Geology and tectonic setting of the Fornovolasco area, Alpi Apuane (Tuscany, Italy)

The study area is located in the Alpi Apuane (Tuscany, Italy), and extends between N 44° 0′ 49.883′′ –E 10°20′ 23.467′′ (SW corner) and N 44°2′ 53.403′′ –E 10°23′19.175′′ (NE corner). The area shows a pile of tectonic units belonging either to the Apuane metamorphic complex, and Tuscan Nappe, stacked during the Alpine orogeny. The latter is represented by a sedimentary Triassic-Miocene succession, and it is characterized by a large-scale east-dipping monocline, with local excision of stratigraphic terms due to the occurrence of intra-unit low-angle normal faults. The Apuane metamorphic complex is formed by Paleozoic phyllites, post-Variscan magmatic rocks (Fornovolasco Metarhyolite Fm.), and Mesozoic-Tertiary metasedimentary formations. The 1:5000 scale geological map and the cross-sections illustrate the tectonic setting of the Fornovolasco area, resulting from the Tertiary tectono-metamorphic events. In the Fornovolasco area, small Tl-rich pyrite + magnetite ore bodies occur close to the contacts between the Paleozoic basement and the cover metasedimentary formations

Probabilistic rainfall thresholds for triggering debris flows in a human-modified landscape

Abstract In the Carrara Marble Basin (CMB; Apuan Alps, Italy) quarrying has accumulated widespread and thick quarry waste, lying on steep slopes and invading valley bottoms. The Apuan Alps are one of the rainiest areas in Italy and rainstorms often cause landslides and debris flows. The stability conditions of quarry waste are difficult to assess, owing to its textural, geotechnical and hydrogeological variability. Therefore, empirical rainfall thresholds may be effective in forecasting the possible occurrence of debris flows in the CMB. Three types of thresholds were defined for three rain gauges of the \CMB\ and for the whole area: rainfall intensity–rainfall duration (ID), cumulated event rainfall–rainfall duration (ED), and cumulated event rainfall normalized by the mean annual precipitation–rainfall intensity (EMAPI). The rainfall events recorded from 1950 to 2005 was analyzed and compared with the occurrence of debris flows involving the quarry waste. They were classified in events that triggered one or more debris flows and events that did not trigger debris flows. This dataset was fitted using the logistic regression method that allows us to define a set of thresholds, corresponding to different probabilities of failure (from 10% to 90%) and therefore to different warning levels. The performance of the logistic regression in defining probabilistic thresholds was evaluated by means of contingency tables, skill scores and receiver operating characteristic (ROC) analysis. These analyses indicate that the predictive capability of the three types of threshold is acceptable for each rain gauge and for the whole CMB. The best compromise between the number of correct debris flow predictions and the number of wrong predictions is obtained for the 40% probability thresholds. The results obtained can be tested in an experimental debris flows forecasting system based on rainfall thresholds, and could have implications for the debris flow hazard and risk assessment in the CMB

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Estimation of the susceptibility of a road network to shallow landslides with the integration of the sediment connectivity

Abstract. Landslides cause severe damage to the road network of the hit zone, in terms of both direct (partial or complete destruction of a road or blockages) and indirect (traffic restriction or the cut-off of a certain area) costs. Thus, the identification of the parts of the road network that are more susceptible to landslides is fundamental to reduce the risk to the population potentially exposed and the financial expense caused by the damage. For these reasons, this paper aimed to develop and test a data-driven model for the identification of road sectors that are susceptible to being hit by shallow landslides triggered in slopes upstream from the infrastructure. This model was based on the Generalized Additive Method, where the function relating predictors and response variable is an empirically fitted smooth function that allows fitting the data in the more likely functional form, considering also non-linear relations. This work also analyzed the importance, on the estimation of the susceptibility, of considering or not the sediment connectivity, which influences the path and the travel distance of the materials mobilized by a slope failure until hitting a potential barrier such as a road. The study was carried out in a catchment of northeastern Oltrepò Pavese (northern Italy), where several shallow landslides affected roads in the last 8 years. The most significant explanatory variables were selected by a random partition of the available dataset in two parts (training and test subsets), 100 times according to a bootstrap procedure. These variables (selected 80 times by the bootstrap procedure) were used to build the final susceptibility model, the accuracy of which was estimated through a 100-fold repetition of the holdout method for regression, based on the training and test sets created through the 100 bootstrap model selection. The presented methodology allows the identification, in a robust and reliable way, of the most susceptible road sectors that could be hit by sediments delivered by landslides. The best predictive capability was obtained using a model in which the index of connectivity was also calculated according to a linear relationship, was considered. Most susceptible road traits resulted to be located below steep slopes with a limited height (lower than 50 m), where sediment connectivity is high. Different land use scenarios were considered in order to estimate possible changes in road susceptibility. Land use classes of the study area were characterized by similar connectivity features. As a consequence, variations on the susceptibility of the road network according to different scenarios of distribution of land cover were limited. The results of this research demonstrate the ability of the developed methodology in the assessment of susceptible roads. This could give the managers of infrastructure information about the criticality of the different road traits, thereby allowing attention and economic budgets to be shifted towards the most critical assets, where structural and non-structural mitigation measures could be implemented

shallow landslides susceptibility assessment in different environments

The spatial distribution of shallow landslides is strongly influenced by different climatic conditions and environmental settings. This makes difficult the implementation of an exhaustive monitoring technique for correctly assessing the landslide susceptibility in different environmental contexts. In this work, a unique methodological strategy, based on the statistical implementation of the generalized additive model (GAM), was performed. This method was used to investigate the shallow landslide predisposition of four sites with different geological, geomorphological and land-use characteristics: the Rio Frate and the Versa catchments (Southern Lombardy) and the Vernazza and the Pogliaschina catchments (Eastern Liguria). A good predictive overall accuracy was evaluated computing by the area under the ROC curve (AUROC), with values ranging from 0.76 to 0.82 and estimating the mean accuracy of the model (0.70–0.75). The method showed a high flexibility, which led to a good identification of the most significant predisposing factors for shallow landslide occurrence in the different investigated areas. In particular, detailed susceptibility maps were obtained, allowing to identify the shallow landslide prone areas. This methodology combined with the use of the rainfall thresholds for triggering shallow landslides may provide an innovative tool useful for the improvement of spatial planning and early warning systems

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good