RS & GIS-based landslide susceptibility mapping of the Balason River basin,Darjeeling Himalaya,using logistic regression (LR) model

The present study deals with the preparation of a landslide susceptibility map of the Balason River basin, Darjeeling Himalaya, using a logistic regression model based on Geographic Information System and Remote Sensing. The landslide inventory map was prepared with a total of 295 landslide locations extracted from various satellite images and intensive field survey. Topographical maps, satellite images, geological, geomorphological, soil, rainfall and seismic data were collected, processed and constructed into a spatial database in a GIS environment. The chosen landslide-conditioning factors were altitude, slope aspect, slope angle, slope curvature, geology, geomorphology, soil, land use/land cover, normalised differential vegetation index, drainage density, lineament number density, distance from lineament, distance to drainage, stream power index, topographic wetted index, rainfall and peak ground acceleration. The produced landslide susceptibility map satisfied the decision rules and ?2 Log likelihood, Cox &; Snell R-Square and Nagelkerke R-Square values proved that all the independent variables were statistically significant. The receiver operating characteristic curve showed that the prediction accuracy of the landslide probability map was 96.10%. The proposed LR method can be used in other hazard/disaster studies and decision-making.     

Integration of satellite remote sensing and geophysical techniques (electrical resistivity tomography and ground penetrating radar) for landslide characterization at Kunjethi (Kalimath), Garhwal Himalaya,India

Natural Hazards - During the extreme precipitation event of 15th–17th June 2013 in Garhwal Himalaya, glacial lake outburst flooding accompanied by numerous landslides and flash flood events...     

Paleoseismological investigations along Joggers Park Fault,Port Blair,South Andaman: Implications towards delineation of blind thrusting and related crustal deformation through ground penetrating radar (GPR) and electrical resistivity techniques (ERT and VES)

A comprehensive paleoseismological investigations was carried out along Joggers Park Fault (striking NW-SE) reveals pervasive traces of active compressional tectonics (blind thrusting) and shallow-surface recent tectonic signatures along the fault. The geometry and trends in the tectonic deformation of the blind zone (shallow-subsurface stratigraphy) were examined with GPR and electrical resistivity tomography (ERT) and vertical electrical sounding (VES), strongly demonstrates severe tectonic deformation (persistent tectonic style) from Quaternary to Holocene times in a compressive stress regime. The surface manifestation of deformation (topographic expression) along the fault can be marked as hanging wall uplift and can be visually observed in the exposed sections at nearly half kilometer distance from the table land of Joggers Park in the form of a well-defined disconnected high angle thrust fault scarp (reverse fault). The reverse fault kinematically and intimately linked with underlying fault geometry provides adduced evidence to evaluate strike displacement profiles (displacement length relationship) along the fault. In addition, deformed stacked colluvial wedge below the scarp represents a powerful basis to calibrate recent and long term slip rates of the underlying fault.     

A geochemical and isotopic assessment of hydraulic connectivity of a stacked aquifer system in the Lisbon Valley,Utah (USA), and critical evaluation of environmental tracers

Hydrogeology Journal - This study investigates hydraulic connectivity of a stacked aquifer system in the Lisbon Valley of southeastern Utah (USA), within the Paradox Basin, where numerous faults...     

Flood hazard assessment and mapping of River Swat using HEC-RAS 2D model and high-resolution 12-m TanDEM-X DEM (WorldDEM)

Natural Hazards - Floods are among the most devastating and recurring natural hazards and have caused extensive economic losses to human lives and infrastructures around the world. Swat valley in...     

Correction to: Flood hazard assessment and mapping of River Swat using HEC-RAS 2D model and high-resolution 12-m TanDEM-X DEM (WorldDEM)

Natural Hazards - The original article was updated and corrected due to numbering errors in Figure 8’s subfigures and the placement of some of the article’s other figures. Additional...     

ESR dating of level L 2/3 at La Micoque (Dordogne), France: Excavations of Debénath and Rigaud

Electron spin resonance (ESR) dates have been obtained on enamel from horse teeth found in Layer L 2/3 of the lower Paleolithic archaeological site of La Micoque. the age given by six of the seven samples analyzed is between 241 ± 15 and 288 ± 10 ka, the ages given by models that postulate early or continuous (linear) uptake of uranium by the tooth, respectively.     

An assessment of biases associated with caging,tethering, and trawl sampling of summer flounder (<Emphasis Type="Italic">Paralichthys dentatus</Emphasis>)

We provide an example of the type of bias assessment that should, but often is not, used in ecological studies using techniques such as caging, tethering, and trawl sampling. Growth rates of summer flounder (Paralichthys dentatus) from cage enclosures were compared to those from mark-recapture trials, and prey types (identified through stomach content analysis) compared between caged fish and wild fish collected from nursery sites over a 2-yr period. Site-specific growth rates estimated from the caging method were similar (± 15%) to those estimated from the mark-recapture trials. Prey types were nearly identical between caged and wild fish, although selectivity may have varied quantitatively. Caging summer flounder will generally be an appropriate tool with which to measure growth rates in the wild, but comparisons with an independent measurement method are necessary for validation. In tethering trials, predation was significantly greater on tethered than on untethered fish, indicating that tethering is not an appropriate tool with which to measure absolute rates of predation on juvenile summer flounder. The lack of effects of substrate (sand versus mud) and fish origin (hatchery-reared versus wild) on predation of tethered versus untethered fish indicates that tethering trials will not indicate treatment-specific differences when none exist. Tethering may be an acceptable method for comparing relative rates of predation on different substrates and between hatchery-reared and wild juvenile summer flounder in the field, although true differences in treatment levels could be masked by tethering. Beam trawl efficiency estimates for juvenile summer flounder were similar between beach and marsh habitats, but differed significantly between marsh sites, indicating that site-specific trawl efficiency estimates may be critical to accurately assess juvenile flounder the appropriateness of comparisons of size-frequency information between the sites and habitats used in this study. Caging, tethering, and beam trawl sampling are appropriate tools for measuring ecological parameters of juvenile summer flounder, but only if possible biases of each method are identified and compensated for when interpreting data collected using these methods.     

An earth systems approach to understanding the tectonic and cultural landscapes of linked marine embayments: Avon‐Heathcote Estuary (Ihutai) and Lake Ellesmere (Waihora), New Zealand

An earth systems study of the Avon‐Heathcote Estuary (Ihutai), New Zealand, shows that tectonic activity has a marked direct and indirect control upon its geomorphology and human settlement in the area. We discuss the Late Holocene history of the embayment in relation to large earthquakes and their after‐effects. Of particular note is the rapid fluvial transfer of sand to the coast causing dune formation and a more delayed pulse of coarser sediment causing channel avulsion of the Waimakariri River. While dune system development seems to occur soon after tectonic activity, river channel avulsion, spit/barrier formation and ongoing geomorphological changes may well relate to periods of tectonic activity that occurred 100–200 years previously. The interaction between these two sediment delivery systems causes significant, and often rapid, changes to coastal geomorphology and ecosystems that have serious implications for human populations living at or near the coast. We show a more region‐wide picture of the direct and indirect effects of tectonic activity, by comparing two embayments that represent coastal points of entry at opposite ends of the Waimakariri River floodplain: the Avon‐Heathcote Estuary (Ihutai) and Lake Ellesmere (Waihora). Copyright © 2005 John Wiley & Sons, Ltd.     

Solid-liquid equilibria of Mg(OH)2(cr) and Mg2(OH)3Cl·4H2O(cr) in the system Mg-Na-H-OH-Cl-H2O at 25°C

The solubility of crystalline Mg(OH)₂(cr) was determined by measuring the equilibrium H⁺ concentration in water, 0.01-2.7 m MgCl₂, 0.1-5.6 m NaCl, and in mixtures of 0.5 and 5.0 m NaCl containing 0.01-0.05 m MgCl₂. In MgCl₂ solutions above 2 molal, magnesium hydroxide converted into hydrated magnesium oxychloride. The solid-liquid equilibrium of Mg₂(OH)₃Cl·4H₂O(cr) was studied in 2.1-5.2 m MgCl₂. Using known ion interaction Pitzer coefficients for the system Mg-Na-H-OH-Cl-H₂O (25°C), the following equilibrium constants at I = 0 are calculated:

     

Early generation of 20S-5α(H),14α(H),17α(H)- and 5α(H),14β(H),17β(H)-steranes in low salinity lacustrine shales

A quantitative sterane biomarker study was conducted on a series of paralic freshwater lacustrine shale samples ranging in maturity from immature to near oil window maturity taken from Section 3 of the Shahejie Formation (Es3) in the Liaohe Basin, N.E. China. Concentrations of 5α(H),14α(H),17α(H)-20S and 5α(H),14β(H),17β(H)-steranes remain nearly constant throughout the sample suite. However, the decrease in the absolute concentrations of the 20R-5α(H),14α(H),17α(H)-C₂₉ steranes with increasing maturity results in an increase in the conventionally defined maturity parameters, 20S/(20S + 20R)-ααα and αββ/(ααα + αββ) sterane ratios. In addition, the data suggest that relatively early generation of 5α(H),14α(H),17α(H)-20S and 5α(H),14β(H),17β(H)-steranes has occurred in lacustrine sediments with a vitrinate reflectance 0.3% (R_o). The data provide strong support for the major importance of relative thermal stability of epimers, but do not exclude the possibility of isomerization as a viable mechanism for production.     

(Im)mobilization of soil heavy metals using CaO,FA, sulfur,and Na<Subscript>2</Subscript>S: a 1-year incubation study

The immobilization of heavy metals (HMs)-contaminated soils using amendments is a cost-effective remediation technique. Therefore, the aim of this study was to evaluate the effectiveness and aging factor of CaO, fly ash (FA), sulfur, and Na₂S on the immobilization of Cd, Cu, and Pb in three different contaminated soils under 1-year incubation. The study sites (S) and amendments treatments (T) are termed as S1, S2, and S3 and T1, T2, T3, and T4, respectively. The TCLP-extractable HMs were analyzed in treated soils after 2, 6, and 12 months. The higher concentrations of CaO, FA, and Na₂S (T3 and T4) efficiently immobilized the Cd. However, a moderate Cd decrease was noted in sulfur-treated samples with no significant difference in ratios as compared to control in used soils. Likewise, CaO decreased moderately Cu content in used soils with gradual increase in Cu mobility. Similarly, FA, sulfur, and Na₂S showed effective immobilization of Cu content with no difference in treatment ratios as compared to control. In addition, CaO, sulfur, and Na₂S decreased the significant content of Pb as compared to control. However, FA treatments showed moderate reduction in Pb content with no difference in ratios. The higher concentrations of alkaline amendments should be avoided in the farmland soils as they increase the soil pH and EC of soil ecosystem. The higher ratios of alkaline amendments would be suitable to remediate the abandoned lands/brownfields. The sulfur amendment would be suitable for immobilization of metals in alkaline soils rather than in acidic soils.     

Cocrystallization of isomorphic components in solutions and crystal zoning: An example of the (Ba,Pb)(NO<Subscript>3</Subscript>)<Subscript>2</Subscript> series

The phase equilibrium and growth of mixed (Ba,Pb)(NO₃)₂ crystals in aqueous solutions were investigated. The microcrystallization method was adapted to systems with isomorphic components, where crystal composition deviates from the thermodynamic equilibrium even at a low supercooling. The solid phase is characterized by continuous miscibility of the components within the analyzed ranges of temperature and solution composition. The diagram is characterized by substantial nonlinearity of the solubility isotherms and nonuniformity of the solid isocomposite location. Quasiequilibrium paths change their slope depending on solution enrichment in Ba(NO₃)₂ and depletion in Pb(NO₃)₂. The area of curvature of quasiequilibrium paths is coordinated with the area of the changing isotherm slope, i.e., the area of “remarkable” points, where the behavior of the system changes drastically. Examples of theoretical zoning of a crystal approximated to a sphere were calculated for paths at a temperature decreasing from 50 to 15°C. The content of the Ba component decreases toward the periphery with the consecutive overgrowing of zones. Each zone corresponds to one gram of (Ba,Pb)(NO₃)₂. Crystals grown from different initial solutions consist of different numbers of zones owing to the nonlinearity of solubility isotherms. Specific features of mixed crystal formation should be taken into account in genetic interpretation of natural minerals of mixed composition.     

An experimental study of glaucophanic amphiboles in the system Na2O-MgO-Al2O3-SiO2-SiF4 (NMASF): some implications for glaucophane stability in natural and synthetic systems at high temperatures and pressures

The phase relations of glaucophanic amphiboles have been studied at 18–31 kbar/680–950°C in the synthetic system Na₂O–MgO–Al₂O₃–SiO₂–SiF₄ (NMASF) using the bulk composition of fluor-glaucophane, Na₂Mg₃Al₂Si₈O₂₂F₂. Previous experimental studies of glaucophane in the water-bearing system (NMASH) have been hampered by problems of fine grain size (electron microprobe analyses with low oxide totals and contamination by other phases), and consequently good compositional data are lacking. Fluor-amphiboles, on the other hand, generally have much higher thermal stabilities than their hydrous counterparts. By using the fluorine-analogue system NMASF, amphibole crystals sufficiently coarse for electron microprobe analysis have been obtained. Furthermore, NMASH amphibole phase relations are directly analogous to those of the NMASF system because SiF₄ fills the role of H₂O as the fluid species. High-pressure NMASF amphibole parageneses are comparable to those obtained for NMASH amphiboles under similar pressure-temperature conditions, except that the NMASF solidus was not encountered. In the pressure-temperature range of the NMASF experiments, fluor-glaucophane is unstable relative to glaucophanenyböite-Mg-magnesio-katophorite amphiboles. Variations in synthetic fluor-amphibole composition with P and T are discussed in terms of changes in the thermodynamic activities of the principal amphibole end-members, such as glaucophane (a_Gp) and nyböite (a_Ny) using an ideal-mixing-on-sites model. The most glaucophanic amphiboles analysed have a_Gp=0.50–0.60 and coexist with jadeite and coesite at 30 kbar/800°C. Amphiboles become increasingly nyböitic with decreasing pressure through the NaAlSi_-1 exchange, which is the principal variation observed. The most nyböitic amphiboles have a_Ny =0.65–0.70 and coexist with fluor-sodium-phlogopite and quartz at 21–24 kbar/800–850°C. At 800°C amphiboles are essentially glaucophane-nyböite solid solutions. At 850°C there is some minor displacement along MgMgSi_-1, but Mg-magnesio-katophorite activities are very low (<0.06). Activities of the eight other NMASF amphibole end-members are <0.001, except for eckermannite activity which varies from 0.01–0.11. Our results indicate that: (a) synthetic amphiboles mimic the essential stoichiometries observed in blueschist amphiboles; (b) synthetic studies should be relevant to petrologically important high-pressure parageneses and reactions involving glaucophanicamphiboles, sodic pyroxenes, albite and talc; (c) the high-pressure stability limit of fluorglaucophane lies at pressures higher than those reached in this study (31 kbar); (d) in natural systems an approach to glaucophane stoichiometry should be favoured by high water activities as well as high pressures.Abbreviations and formulae used in this paper Glaucophane (Gp) oNa₂(Mg₃Al₂)Si₈O₂₂(OH,F)₂ - Nyböite (Ny) NaNa₂(Mg₃Al₂)Si₇AlO₂₂(OH,F)₂ - Eckermannite (Ek) NaNa₂(Mg₄Al)Si₈O₂₂(OH,F)₂ - Magnesio-cummingtonite (MC) oMg₂(Mg₅)Si₈O₂₂(OH,F)₂ - Sodium-magnesio-cummingtonite (SMC) NaNaMg(Mg₅)Si₈O₂₂(OH,F)₂ - Sodium-anthophyllite (SAn) NaMg₂(Mg₅)Si₇AlO₂₂(OH,F)₂ - Gedrite (Gd) oMg₂(Mg₃Al₂)Si₆Al₂O₂₂(OH,F)₂ - Sodium-gedrite (SGd) NaMg₂(Mg₄Al)Si₆Al₂O₂₂(OH,F)₂ - Mg-magnesio-aluminotaramite (MAT) NaNaMg(Mg₃Al₂)Si₆Al₂O₂₂(OH,F)₂ - Mg-magnesio-katophorite (MKt) NaNaMg(Mg₄Al)Si₇AlO₂₂(OH,F)₂ - Mg-magnesio-barroisite (MBa) oNaMg(Mg₄Al)Si₇AlO₂₂(OH,F)₂ - Jadeite (Jd) NaAlSi₂O₆ - Enstatite (En) Mg₂Si₂O₆ - Forsterite (Fo) Mg₂SiO₄ - Nepheline (Ne) NaAlSiO₄ - Albite (Ab) NaAlSi₃O₈ - Quartz/Coesite (Qz/Co) SiO₂ - Sodium-phlogopite (Sphl) NaMg₃Si₃AlO₁₀(OH,F)₂ - Talc (Tc) oMg₃Si₄O₁₀(OH,F)₂ - o vacant A-site in amphiboles and interlayer site in talc. Octahedral cations in amphiboles are bracketted