An uncertainty and sensitivity analysis approach for GIS-based multicriteria landslide susceptibility mapping

GIS-based multicriteria decision analysis (MCDA) methods are increasingly being used in landslide susceptibility mapping. However, the uncertainties that are associated with MCDA techniques may significantly impact the results. This may sometimes lead to inaccurate outcomes and undesirable consequences. This article introduces a new GIS-based MCDA approach. We illustrate the consequences of applying different MCDA methods within a decision-making process through uncertainty analysis. Three GIS-MCDA methods in conjunction with Monte Carlo simulation (MCS) and Dempster–Shafer theory are analyzed for landslide susceptibility mapping (LSM) in the Urmia lake basin in Iran, which is highly susceptible to landslide hazards. The methodology comprises three stages. First, the LSM criteria are ranked and a sensitivity analysis is implemented to simulate error propagation based on the MCS. The resulting weights are expressed through probability density functions. Accordingly, within the second stage, three MCDA methods, namely analytical hierarchy process (AHP), weighted linear combination (WLC) and ordered weighted average (OWA), are used to produce the landslide susceptibility maps. In the third stage, accuracy assessments are carried out and the uncertainties of the different results are measured. We compare the accuracies of the three MCDA methods based on (1) the Dempster–Shafer theory and (2) a validation of the results using an inventory of known landslides and their respective coverage based on object-based image analysis of IRS-ID satellite images. The results of this study reveal that through the integration of GIS and MCDA models, it is possible to identify strategies for choosing an appropriate method for LSM. Furthermore, our findings indicate that the integration of MCDA and MCS can significantly improve the accuracy of the results. In LSM, the AHP method performed best, while the OWA reveals better performance in the reliability assessment. The WLC operation yielded poor results.     

Returning home: migrant connections and visions for local development in rural Nepal

Migration to domestic and international destinations has become an emblematic feature of Nepal’s societal changes. Part of this development is education migration from rural to urban areas within the borders of Nepal, an often overlooked but increasingly important aspect of contemporary migration flows. By focusing on these educational migrants, this paper explores how they connect to their rural homes. Guided by a critical reading of the migration-development scholarship, the paper examines how migrants and their relatives make sense of educational migrants’ remitting and returning practices, and by comparing three groups of educational migrants, the migrants’ reasons for staying connected and sending remittances are scrutinized. The paper finds that although educational migrants do not generate extensive economic remittances for local development in Nepal, they stay connected to their rural homes and partake in important social remittance practices that represent a vision for impacting local development.     

Demarcation of homogeneous structural domains within a rock mass based on joint orientation and trace length

This paper presents a new method for determining the structural domain boundaries within the rock mass. This new method is based on a statistical comparison of data from pairs of sample regions. The stereonet is divided into 100 windows with approximately equal areas. The poles of joints occurring in each corresponding window on the two projection plots of the regions being compared are then merged and arranged in ascending order with respect to their trace lengths. Finally, the Wald–Wolfowitz runs test is used to identify the homogeneity of structural populations by analyzing the joint sequence. Based on a significance level of 0.01, the homogeneity of structural populations collected from four adjacent adits at the Songta dam site is determined using the proposed method. The results show that the boundaries of structural domain change with the sizes of the sampling domains being compared. The initial sampling domains should be selected according to the engineering geological conditions of the studied area. In addition, the clear advantage of the proposed method is that both joint orientation and trace length are considered.     

Plate tectonic settings for Precambrian basic rocks from Brazil by multidimensional tectonomagmatic discrimination diagrams and their limitations

Multidimensional discrimination diagrams (2006–2011) for basic and ultrabasic igneous rocks were applied to Precambrian rock suites from the Amazonian and São Francisco cratons, and the Tocantins Province, Brazil, to infer their possible tectonic settings. The chosen study cases in the Amazonian craton include the ca. 3.0 Ga metabasalts of the Identidade greenstone belt, 1.87–1.80 Ga Parauapebas anorogenic basalt-rhyolite dikes, 1.86–1.82 Ga Rio Branco anorogenic gabbro-basalt association, ca. 1.76–1.74 Ga Aripuanã and Teles Pires intracratonic basalt-felsic volcanic associations, and 1.76–1.74 Ga Jamari and 1.60–1.53 Ga Serra da Providência arc-related gabbroic rocks. In the São Francisco craton, we selected 1.48 Ga arc-related amphibolites of the Rio Capim greenstone belt, continental mafic dikes of Uauá (2.6 Ga), Curaçá and Chapada Diamantina (1.5 Ga), and Espinhaço (ca. 1.0 Ga). In the Tocantins Province, ca. 3.0 Ga komatiites associated with oceanic basalts of the Crixás and Guarinos greenstone belts were studied. The application of the diagrams generally provided consistent results with the authors’ proposed tectonic settings based on field relationships and geochemical data. The exceptions are some within-plate (continental) mafic dikes and basalts for which our diagrams do not work well. For comparison, we also used two ternary and two bivariate traditional discrimination diagrams for the data from the Amazonian craton, whose results were poorer than the newer multidimensional diagrams.     

A cave in Dolerite at Wayatinah,Tasmania

A cave (60 ft. x 30 ft. x 17 ft.) occurs within Jurassic dolerite 600 ft. from the surface. It was formed by zeolitization of a zone in the dolerite followed by solution of the secondary minerals to leave a cavity.     

Strategy and Scenario for Radioastron Space VLBI Observations

Space VLBI's highly dynamic geometry, ability to access the space radio telescope (SRT) only via distant communication links, very expensive mission cost, and scientific goals define the basic strategy and scenario for mission control and radio source observations. These are very different from those for ground-based VLBI. Space VLBI strategy must be based on the limitation of SRT repointings, periodic orbit determination before astronomical observations, preliminary preparation and checking of space and ground facilities, and recommended observing sequences and modes. A control and observation scenario is considered for an in-orbit-checkout period, and also for short (1-orbit – 1 week) and long (1 week and more) observation sessions. Examples and illustrations are given for the Radioastron space VLBI Project.     

Low energy neutral atoms imaging of the Moon

Imaging of low-energy neutral atoms (LENAs) in the vicinity of the Moon can provide wide knowledge of the Moon from the viewpoint of plasma physics and planetary physics. At the surface of the Moon, neutral atoms are mainly generated by photon-stimulated desorption, micrometeorite vaporization and sputtering by solar wind protons. LENAs, the energetic neutral atoms with energy range of 10-500 eV, are mainly created by sputtering of solar wind particles. We have made quantitative estimates of sputtered LENAs from the Moon surface. The results indicate that LENAs can be detected by a realistic instrument and that the measurement will provide the global element maps of sputtered particles, which substantially reflect the surface composition, and the magnetic anomalies. We have also found that LENAs around dark regions, such as the permanent shadow inside craters in the pole region, can be imaged. This is because the solar wind ions can penetrate shaded regions due to their finite gyro-radius and the pressure gradient between the solar wind and the wake region. LENAs also extend our knowledge about the magnetic anomalies and associated mini-magnetosphere systems, which are the smallest magnetospheres as far as one knows. It is thought that no LENAs are generated from mini-magnetosphere regions because no solar wind may penetrate inside them. Imaging such void areas of LENAs will provide another map of lunar magnetic anomalies.     

GAUGE: the GrAnd Unification and Gravity Explorer

The GAUGE (GrAnd Unification and Gravity Explorer) mission proposes to use a drag-free spacecraft platform onto which a number of experiments are attached. They are designed to address a number of key issues at the interface between gravity and unification with the other forces of nature. The equivalence principle is to be probed with both a high-precision test using classical macroscopic test bodies, and, to lower precision, using microscopic test bodies via cold-atom interferometry. These two equivalence principle tests will explore string-dilaton theories and the effect of space–time fluctuations respectively. The macroscopic test bodies will also be used for intermediate-range inverse-square law and an axion-like spin-coupling search. The microscopic test bodies offer the prospect of extending the range of tests to also include short-range inverse-square law and spin-coupling measurements as well as looking for evidence of quantum decoherence due to space–time fluctuations at the Planck scale.     

Millimetron—a large Russian-European submillimeter space observatory

Millimetron is a Russian-led 12 m diameter submillimeter and far-infrared space observatory which is included in the Space Plan of the Russian Federation for launch around 2017. With its large collecting area and state-of-the-art receivers, it will enable unique science and allow at least one order of magnitude improvement with respect to the Herschel Space Observatory. Millimetron will be operated in two basic observing modes: as a single-dish observatory, and as an element of a ground-space very long baseline interferometry (VLBI) system. As single-dish, angular resolutions on the order of 3 to 12 arc sec will be achieved and spectral resolutions of up to a million employing heterodyne techniques. As VLBI antenna, the chosen elliptical orbit will provide extremely large VLBI baselines (beyond 300,000 km) resulting in micro-arc second angular resolution.     

Photometric mapping of Asteroid (4) Vesta’s southern hemisphere with Hubble Space Telescope

We present the surface mapping of the southern hemisphere of Asteroid (4) Vesta obtained from Hubble Space Telescope (HST). From 105 images of Vesta through four filters in the wavelengths best to characterize the 1-μm pyroxene band, we constructed albedo and color-ratio maps of Vesta. These new maps cover latitudes −50° to +20°. The southern hemisphere of Vesta displays more diverse albedo and color features than the northern hemisphere, with about 15 new albedo and color features identified. The overall longitudinal albedo and color variations in the southern hemisphere are comparable with that of the northern hemisphere, with a range of about ±20% and ±10%, respectively. The eastern hemisphere is brighter and displays more diogenitic minerals than the western hemisphere. Correlations between 1-μm band depth and band width, as well as between 1-μm band depth and albedo, are present on a global scale, attributed to pyroxene composition variations. The lack of correlations between albedo and the spectral slope indicates the absence of globalized space weathering. The lack of a global correlation between 1-μm band depth and topography suggests that the surface composition of Vesta is not completely controlled by a single impact. The distribution of compositional variation on Vesta suggests a possible large impact basin. Evidence of space weathering is found in regions, including the bright rim of the south-pole crater where the steepest gravitational slope on Vesta is, and a dark area near a gravitationally flat area. We propose to divide the surface of Vesta into six geological units different from the background according to their 1-μm absorption features and spectral slopes, including two eucrite-rich units, a low-Ca eucrite unit, a diogenite-rich unit, a space weathered unit, and a freshly exposed unit. No evidence of olivine-rich area is present in these data.