A simplified method for predicting rainfall-induced mobility of active landslides

This paper deals with the landslides that are reactivated by a groundwater level increase owing to rainfall. These landslides are usually characterized by low displacement rate with deformations essentially concentrated within a narrow shear zone above which the unstable soil mass moves like a rigid body (i.e., with a horizontal displacement profile that is essentially constant with depth). In view of this evidence, a new method based on a simple sliding block model is proposed in the present study for a preliminary evaluation of landslide mobility. Unlike other existing methods that provide an evaluation of landslide mobility on the basis of groundwater level measurements, the present method directly relates landslide movements to rain recordings. This possibility constitutes a significant advantage from a practical viewpoint because it allows future displacement scenarios to be predicted from expected rainfall scenarios. In addition, the present method requires a limited number of parameters as input data, many of which can be obtained from conventional geotechnical tests. To evaluate the other parameters involved, an efficient calibration procedure is also proposed. Four case studies documented in the literature are analyzed to assess the capability of the present method to reproduce the main features of the slope response to rainfall. In all these case studies, both groundwater level variations and landslide displacements observed in field are well approximated by the method.     

Regionalisation of the “intensity-duration-frequency” curves in Northern Algeria

The flood events observed during last years in the urban areas are subject of main interest for quantification of the hydro-climatic risks and climatic change to the regional scales. The establishment of a statistical relationship between the intensities of intense rains and the recurrence of these events allows us to determine the dimensions of the works according to a previously defined level of risk. They constitute today a leading tool for various users. This work concerns the study of the maximum annual rains, recorded at 49 stations in the northern Algeria. The objectives of this work are to determine the estimators who are the “intensity-duration-frequency” curves and to extract from these whole of information the b Montana climatic parameter to be regionalized for the calculating the river flow and for the dimensioning of the networks of cleansing in the event of insufficiency of data. Different durations going from 15 min to 24 h are studied. We utilised the collocated co-kriging as multivariate estimation method for interpolation in order to yield the space distribution maps of b Montana climatic parameter, with the benefit of using spatially correlated secondary variables, such as the digital elevation model and the distance from the coastline that are known at any localisation. All features led to choose the digital elevation model as covariate for interpolating b Montana values, yielding a better regionalisation of the studied climatic parameter. The geostatistical handling of b Montana values strictly related to auxiliary variables that constitute physical factors overcomes the data shortage in planning, managing and preventing the rain flood risk.     

Geomorphological mapping for the valorization of the alpine environment. A methodological proposal tested in the Loana Valley (Sesia Val Grande Geopark,Western Italian Alps)

Geomorphological mapping plays a key role in landscape representation: it is the starting point for many applications and for the realization of thematic maps, such as hazard and risk maps, geoheritage and geotourism maps. Traditional geomorphological maps are useful for scientific purposes but they need to be simplified for different aims as management and education. In tourism valorization, mapping of geomorphological resources (i.e., geosites, and geomorphosites), and of geomorphic evidences of past hazardous geomorphological events, is important for increasing knowledge about landscape evolution and active processes, potentially involving geomorphosites and hiking trails. Active geomorphosites, as those widespread in mountain regions, testify the high dynamicity of geomorphic processes and their link with climatic conditions. In the present paper, we propose a method to produce and to update cartographic supports (Geomorphological Boxes) realized starting from a traditional geomorphological survey and mapping. The Geomorphological Boxes are geomorphological representation of single, composed or complex landforms drawn on satellite images, using the official Italian geomorphological legend (ISPRA symbols). Such cartographic representation is also addressed to the analysis (identification, evaluation and selection) of Potential Geomorphosites and Geotrails. The method has been tested in the upper portion of the Loana Valley (Western Italian Alps), located within the borders of the Sesia Val Grande Geopark, recognized by UNESCO in 2013. The area has a good potential for geotourism and for educational purposes. We identified 15 Potential Geomorphosites located along 2 Geotrails; they were ranked according to specific attributes also in relation with a Reference Geomorphosite located in the Loana hydrographic basin and inserted in official national and regional databases of geosites (ISPRA; Regione Piemonte). Finally, the ranking of Potential Geomorphosites allowed to select the most valuable ones for valorization or geoconservation purposes. In this framework, examples of Geomorphological Boxes are proposed as supports to geo-risk education practices.     

Burrowing sculptures as an example in functional morphology

Sculptural patterns that aid the burrowing process are found on the exoskeletons of a broad range of fossil and Recent marine invertebrates. A review of these characters is used to illustrate how theoretical principles of functional morphology have been applied to practical cases. The presence of burrowing sculptures has allowed the recognition of burrowing habits and the reconstruction of the burrowing mechanism in several extinct groups, including linguliform brachiopods, trilobites and mitrates.     

On ground-level visibilities in the Po-Valley during winter,and on their intercorrelations

Summary Results of intercorrelations between daily average visibilities, at 18 Observatories situated in the Po-Valley, indicate the existence there of several areas within which conditions of fog are similarly affected. The position of those areas reflects the influence of geographic and topographic factors on fogs which regularly recur, during the cold seasons, in that extensive part of Northern Italy.     

Uranium in submarine metalliferous deposits

Hydrothermal submarine metalliferous deposits, common in areas of the ocean floor with high heat flow, contain generally about 10 ppm U as an order of magnitude. The $\text{U}{}^{234}\text{U}{}^{238}$ ratio is in the majority of cases close to that of seawater; only in a few cases is it anomalously high. Anomalous $\text{U}{}^{234}\text{U}{}^{238}$ ratios are coupled with low U concentrations. These data are explained by a model where thermal water (essentially heated seawater) in its sub-bottom circulation often is unable to leach U from the basaltic oceanic crust; in fact, these thermal waters may in some cases lose U. When leaching of U from the basalt does take place, probably during shallow stages of the sub-bottom circulation, the resulting anomalous $\text{U}{}^{234}\text{U}{}^{238}$ ratio can be preserved in the hydrothermal deposit only if mixing with ‘seawater’ U is prevented.     

Formation of nitrite during the decomposition of aqueous ammonium niumate,under natural ultraviolet radiation

Summary The photodecomposition of ammonium nitrate at various concentrations, in ventilated, aqueous solutions, is investigated as a function of radiation intensity, both under sunlight illumination and under artificial ultraviolet light. The process of decomposition, to nitrogen and water, of ammonium nitrite formed, competes with the formation of NO ₂ ^– which is, otherwise, proportional to the radiation absorbed.     

Change of aqueous sodium nitrate under natural and artificial ultraviolet radiation

Summary The process of nitrite formation, by the action of the near-ultraviolet radiation on sodium nitrate solutions, is investigated both in the laboratory and at different elevations under sunlight. The release of NO _x , from solutions irradiated, is found to compete with the generation of nitrite which is proportional to the radiation absorbed by the solution.     

Palagonite,hyaloclastites and alteration of volcanic glass in the ocean

Palagonite is an hydrated and often altered glass usually associated with sub-aqueous basaltic volcanites. It is commonly considered as an alteration product of normal basaltic glass (sideromelane) with which it is associated in hyaloclastites. Existing information on the diffusion rates of water in natural glasses suggests, however, that the hydration which causes the formation of palagonite takes place at relatively high temperature, that is mainly during effusion and cooling of the lava under water. It is also suggested that generally palagonite is not formed in nature to any great extent from the alteration of sideromelane. Palagonite appears to devitrify much faster than normal unhydrated glass of the same composition. This fact may explain some previously unclear data on the occurrence of volcanic glasses on the floor of the oceans; namely, the existence of totally devitrified glasses in some recent sediments and the finding of unaltered glass in older deposits.