scholarly journals Seismites in the Kathmandu basin, Nepal

1998 ◽  
Vol 18 ◽  
Author(s):  
A. P. Gajurel ◽  
P. Huyghe ◽  
C. France- Lanord ◽  
J. L. Mugnier ◽  
B. N. Upreti ◽  
...  
Keyword(s):  
Sandy Loam ◽  
Hanging Wall ◽  
Coarse Sand ◽  
Small Scale ◽  
Seismic Events ◽  
Silty Clay ◽  
Lacustrine Deposits ◽  
M Sequence ◽  
Water Saturated ◽  
Sandy Sediments

The Kathmandu valley is a large intermontane basin carried above the Himalayan major decollement. It is limited southward by the Mahabharat Range, which forms the hanging wall of the Mahabharat Thrust, and northward by the Shivapuri Range. The Kathmandu basin is filled with a very thick (500-600 m) sequence of fluvio-lacustrine Plio-Pleistocene sediments, which unconformably overlie the folded and faulted Precambrian-Palaeozoic Kathmandu Complex. These semi-consolidated deposits mainly consist of fine to coarse sand, sandy loam, sandy silty clay, and gravely conglomerate. New field data show that small-scale deformational structures occur in the lacustrine deposits of the central and southern parts of the Kathmandu basin. In Thimi section, these structures take place within sub­ horizontal clayey layers. They mainly consist of finely contorted and folded sandy layers which form balls and pillows of about 10-13cm thick. In a few places, the deformational structures are associated with small folds and micro-faults (normal and reverse faults), with micro-breccias and sand dykes. The convolute lamination structures show no preferential verging, thus, excluding shearing related to the influence of a palaeoslope. Such structures have been found in three different places and they were always confined to single stratigraphic horizons positioned between undisturbed parallel beds. The deformational structures described above show characteristics of seismites. The associated seismic events may be related to major earthquakes or movements along the active nearby faults. Earthquake-induced liquefaction and subtle variations in physiomechanical properties of water-saturated fine sandy sediments have probably controlled the deformational pattern.

scholarly journals USING WASTEPAPER SLUDGE ASH (WSA) AS A MATERIAL FOR SOIL STRENGTHENING FOR THE CONSTRUCTION OF LAYERS OF PAVEMENT

2021 ◽  
Vol 2021 (1) ◽  
pp. 85-91
Author(s):  
Serhiy Solodkyy ◽  
◽  
Volodymyr Hidei ◽  
Iurii Sidun ◽  
Oleksii Hunyak ◽  
...  
Keyword(s):  
Sandy Loam ◽  
Strength Criterion ◽  
Soil Reinforcement ◽  
Silty Clay ◽  
Silty Clay Loam ◽  
Different Types ◽  
Stabilized Soil ◽  
Soil Skeleton ◽  
Sludge Ash ◽  
Water Saturated

The article considers the possibility of using wastepaper sludge ash (WSA) as a soil reinforcement material for the construction of layers of road wear. Loamy sand, sandy loam, silty clay loam, silty clay were chosen as soils for strengthening. The maximum density of the soil skeleton at optimum humidity was established by the method of Proctor. Wastepaper sludge ash and Portland cement grade 400 were used separately for soil strengthening. Six compositions of strengthened soil for each type of soil were investigated according to the strength criterion of water-saturated samples at the age of seven, fourteen and twenty-eight days. The research results indicate that wastepaper sludge ash can be used to strengthen different types of soils with the achievement of following grades of stabilized soil: M10, M20, M40.

scholarly journals Soil Texture Alters the Impact of Salinity on Carbon Mineralization

Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 128
Author(s):  
Ruihuan She ◽  
Yongxiang Yu ◽  
Chaorong Ge ◽  
Huaiying Yao
Keyword(s):  
Soil Texture ◽  
Clay Soil ◽  
Sandy Loam ◽  
Microbial Community Composition ◽  
Clay Content ◽  
Interactive Effects ◽  
Silty Clay ◽  
C Mineralization ◽  
Negative Effect ◽  
Silty Clay Soil

Soil salinization typically inhibits the ability of decomposer organisms to utilize soil organic matter, and an increase in soil clay content can mediate the negative effect of salinity on carbon (C) mineralization. However, the interactive effects of soil salt concentrations and properties on C mineralization remain uncertain. In this study, a laboratory experiment was performed to investigate the interactive effects of soil salt content (0.1%, 0.3%, 0.6% and 1.0%) and texture (sandy loam, sandy clay loam and silty clay soil with 6.0%, 23.9% and 40.6% clay content, respectively) on C mineralization and microbial community composition after cotton straw addition. With increasing soil salinity, carbon dioxide (CO2) emissions from the three soils decreased, but the effect of soil salinity on the decomposition of soil organic carbon varied with soil texture. Cumulative CO2 emissions in the coarse-textured (sandy loam and sandy clay loam) soils were more affected by salinity than those in the fine-textured (silty clay) soil. This difference was probably due to the differing responses of labile and resistant organic compounds to salinity across different soil texture. Increased salinity decreased the decomposition of the stable C pool in the coarse-textured soil, by reducing the proportion of fungi to bacteria, whereas it decreased the mineralization of the active C pool in the fine-textured soil through decreasing the Gram-positive bacterial population. Overall, our results suggest that soil texture controlled the negative effect of salinity on C mineralization through regulating the soil microbial community composition.

Contrast between sandy and clay soils in the effects of various factors on the growth, nitrogen uptake and yield of winter wheat in three years

1988 ◽  
Vol 110 (1) ◽  
pp. 119-140 ◽  
Author(s):  
G. N. Thorne ◽  
P. J. Welbank ◽  
F. V. Widdowson ◽  
A. Penny ◽  
A. D. Todd ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Grain Yield ◽  
Sandy Soil ◽  
Barley Yellow Dwarf Virus ◽  
Sandy Loam ◽  
N Uptake ◽  
Dry Weight ◽  
Silty Clay ◽  
Early Application ◽  
Number Of Shoots

SummaryWinter wheat grown following potatoes on a sandy loam at Woburn in 1978–9, 1980–1 and 1981–2 was compared with that on a clay loam at Rothamsted in 1978–9 and 1980–1, and on a silty clay (alluvium) at Woburn in 1981–2. The cultivar was Hustler in the harvest years 1979 and 1981 and Avalon in 1982. On each soil in each year multifactorial experiments tested effects of combinations of six factors, each at two levels.The best 4-plot mean grain yield ranged from 89 to 11·1 t/ha during the 3 years; it was smaller on the sandy soil than on the clay soil in 1979, but larger on sand than on the clay in 1981 and 1982. Until anthesis the number of shoots, dry weight and N content of the wheat giving these best yields were less on sand than on clay. Unlike grain weight, straw weight was always less on sand.Sowing in mid-September instead of mid-October increased grain yield on clay in each year (by 0·4·0·7 t/ha) and increased yield on sand only in 1981 (by 1·6 t/ha). Early sowing always increased dry weight, leaf area, number of shoots and N uptake until May. The benefits were always greater on clay than on sand immediately before N fertilizer was applied in the spring and usually lessened later on both soils.Aldicarb as an autumn pesticide increased grain yield of early-sown wheat on both soils in 1981 by lessening infection with barley yellow dwarf virus. Aldicarb increased yield on clay in 1982; it also decreased the number of plant parasitic nematodes.Wheat on sand was more responsive to nitrogen in division, timing and amount than was wheat on clay. In 1979 yield of wheat on sand was increased by dividing spring N between March, April and May, instead of giving it all in April, and in 1982 by giving winter N early in February. In 1981 division and timing on sand interacted with sowing date. Yield of early-sown wheat given N late, i.e. in March, April and May, exceeded that given N early, i.e. in February, March and May, by 1·4 t/ha; single dressings given all in March or all in April also yielded less than the late divided dressing. Yield of later-sown wheat given all the N in April was at least 1·2 t/ha less than with all N given in March or with divided N. In all years treatments that increased yield usually also increased N uptake. Grain yield on clay was never affected by division or timing of spring N or by application of winter N. This was despite the fact that all treatments that involved a delay in the application of N depressed growth and N uptake in spring on both sand and clay. The mean advantage in N uptake following early application of spring N eventually reversed on both soils, so that uptake at maturity was greater from late than from early application. Increasing the amount of N given in spring from the estimated requirement for 9 t/ha grain yield to that for 12 t/ha increased yield in 1982, especially on sand. The larger amount of N always increased the number of ears but often decreased the number of grains per ear and the size of individual grains.Irrigation increased grain yield only on the sandy soil, by 1·1 t/ha in 1979 and by 07 t/ha in 1981 and 1982. The component responsible was dry weight per grain in 1979 and 1982, when soil moisture deficits reaching maximum values of 136 and 110 mm respectively in the 2 years developed after anthesis; the component responsible was number of ears/m2 in 1982 when the maximum deficit of 76 mm occurred earlier, in late May.

Determination of water content in drying soils: incorporating transition from liquid phase to vapour phase

Soil Research ◽  
2004 ◽  
Vol 42 (1) ◽  
pp. 1 ◽  
Author(s):  
F. Konukcu ◽  
A. Istanbulluoglu ◽  
I. Kocaman
Keyword(s):  
Water Content ◽  
Transition Zone ◽  
Sandy Loam ◽  
Vapour Phase ◽  
Coarse Sand ◽  
Arid Environments ◽  
Evaporation Front ◽  
Matric Potential ◽  
Silty Loam

In arid and semi-arid environments, soil profiles often exhibit a liquid–vapour displacement known as evaporation front characterised by a critical matric potential (ψme) or water content (θe) located somewhere inside the unsaturated zone above a watertable (WT). The objective of this study was to determine the θe including the range of water content (θ) in the transition zone from liquid to vapour both theoretically and experimentally for different soil textures under saline and non-saline WTs. Characteristic shapes of water content and salt concentration profiles were the criteria to obtain θe experimentally, and the θ–diffusivity relationship was used to compute the θe and θ range in the transition zone. Measured θe values of 0.05 and 0.12 m3/m3 under non-saline WT and 0.07 and 0.15 m3/m3 under saline WT were in agreement with the computed values of 0.05 and 0.10 m3/m3 for sandy loam and clay loam soils, respectively. The model calculates roughly the same θe for saline and non-saline conditions. Besides experimental soils, θe and range of θ in the transition zone were calculated for silty loam and coarse sand. The lighter the soil texture, the smaller is θe and the steeper the transition zone. The results were further compared with those calculated by different authors.

A Frequency-Domain-Based Algorithm for Detecting Microseismicity Using Dense Surface Seismic Arrays

2021 ◽  
Author(s):  
Maria Mesimeri ◽  
Kristine L. Pankow ◽  
James Rutledge
Keyword(s):  
Frequency Domain ◽  
Detection Method ◽  
Maximum Amplitude ◽  
High Energy ◽  
Aftershock Sequence ◽  
Anthropogenic Activity ◽  
Small Scale ◽  
Seismic Events ◽  
Small Magnitude ◽  
Seismic Arrays

ABSTRACT We propose a new frequency-domain-based algorithm for detecting small-magnitude seismic events using dense surface seismic arrays. Our proposed method takes advantage of the high energy carried by S waves, and approximate known source locations, which are used to rotate the horizontal components to obtain the maximum amplitude. By surrounding the known source area with surface geophones, we achieve a favorable geometry for locating the detected seismic events with the backprojection method. To test our new detection method, we used a dense circular array, consisting of 151 5 Hz three-component geophones, over a 5 km aperture that was in operation at the Utah Frontier Observatory for Research in Geothermal Energy (FORGE) in southcentral Utah. We apply the new detection method during a small-scale test injection phase at FORGE, and during an aftershock sequence of an Mw 4.1 earthquake located ∼30  km north of the geophone array, within the Black Rock volcanic field. We are able to detect and locate microseismic events (Mw<0) during injections, despite the high level of anthropogenic activity, and several aftershocks that are missing from the regional catalog. By comparing our method with known algorithms that operate both in the time and frequency domain, we show that our proposed method performs better in the case of the FORGE injection monitoring, and equally well for the off-array aftershock sequence. Our new method has the potential to improve microseismic event detections even in extremely noisy environments, and the proposed location scheme serves as a direct discriminant between true and false detections.

Small-scale heterogeneity in carbon dioxide, nitrous oxide and methane production from aggregates of a cultivated sandy-loam soil

2008 ◽  
Vol 40 (9) ◽  
pp. 2468-2473 ◽  
Author(s):  
Benjamin K. Sey ◽  
Ameur M. Manceur ◽  
Joann K. Whalen ◽  
Edward G. Gregorich ◽  
Philippe Rochette
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Methane Production ◽  
Sandy Loam ◽  
Sandy Loam Soil ◽  
Small Scale ◽  
Scale Heterogeneity ◽  
Loam Soil

scholarly journals Assessment of vadose zone sampling methods for detection of preferential herbicide transport

2009 ◽  
Vol 6 (6) ◽  
pp. 7247-7285 ◽  
Author(s):  
N. P. Peranginangin ◽  
B. K. Richards ◽  
T. S. Steenhuis
Keyword(s):  
Vadose Zone ◽  
Preferential Flow ◽  
Sampling Methods ◽  
Sandy Loam ◽  
Silty Clay ◽  
Water Sampling ◽  
Herbicide Transport ◽  
Flow Mechanisms ◽  
Ceramic Cups ◽  
Zone Sampling

Abstract. Accurate soil water sampling is needed for monitoring of pesticide leaching through the vadose zone, especially in soils with significant preferential flowpaths. We assessed the effectiveness of wick and gravity pan lysimeters as well as ceramic cups (installed 45–60 cm deep) in strongly-structured silty clay loam (Hudson series) and weakly-structured fine sandy loam (Arkport series) soils. Simulated rainfall (10–14 cm in 4 d, approximately equal to a 10-yr, 24 h storm) was applied following concurrent application of agronomic rates (0.2 g m−2) of atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) and 2,4-D (2,4-dichloro-phenoxy-acetic acid) immediately following application of a chloride tracer (22–44 g m−2). Preferential flow mechanisms were observed in both soils, with herbicide and tracer mobility greater than would be predicted by uniform flow. Preferential flow was more dominant in the Hudson soil, with earlier breakthroughs observed. Mean wick and gravity pan sampler percolate concentrations at 60 cm depth ranged from 96 to 223 μg L−1 for atrazine and 54 to 78 μg L−1 for 2,4-D at the Hudson site, and from 7 to 22 μg L−1 for atrazine and 0.5 to 2.8 μg L−1 for 2,4-D at the Arkport site. Gravity and wick pan lysimeters had comparably good collection efficiencies at elevated soil moisture levels, whereas wick pan samplers performed better at lower moisture contents. Cup samplers performed poorly with wide variations in collections and solute concentrations.

scholarly journals Analysis of Petrinja 2020 Earthquake (Croatia) and First 500 Aftershocks >M1.0, Identification of Their Sources and Seismogenic Faults

2021 ◽  
Author(s):  
Tihomir Marjanac ◽  
Marina Čalogović ◽  
Karlo Bermanec ◽  
Ljerka Marjanac
Keyword(s):  
Hanging Wall ◽  
Normal Fault ◽  
Seismic Energy ◽  
Seismic Events ◽  
Surface Cracks ◽  
Surface Phenomena ◽  
Slip Mechanism ◽  
Seismogenic Faults ◽  
Water Activation ◽  
Major Fault

Abstract Strong earthquake of M6.4 stroke Petrinja and neighbouring cities of Sisak and Glina in Croatia on December 29th 2020. It was preceded by two foreshocks of M5.2 and M5.0, and followed by a series of aftershocks of various magnitudes and intensities. We have analysed first 500 earthquakes and aftershocks of > M1.0 which occurred from December 28th 2020 to January 19th 2021, their frequency, focal depths, and coseismic surface phenomena. Correlation of focal depths revealed the source of earthquakes was faulting of hanging wall of a listric normal fault with NW-SE strike and dip towards NE. Major fault seems to have caused earthquakes with only minor magnitudes. The strongest two earthquakes of M6.4 and M5.2 were initiated on synthetic fault, whereas M5.0 earthquake was initiated on an antithetic fault. Almost 50% of all seismic energy of the first 500 analysed seismic events over M1.0 was released on 1 km and 10 km deep hypocentres. Focal mechanisms of major earthquakes and strong fore- and aftershocks indicate dextral-slip mechanism, which is also in accordance with the orientation of surface cracks, land faulting and sand volcano trains. Co-seismic surface phenomena are land cracks and fissures, land faults, sand volcanoes, eruptive springing of ground water, activation of landslides, and formation of dozens of collapse sinkholes which continued to form and grow for about a month following the major earthquake.

Validation of Coupled FDM-DEM Approach on the Soil-Raft Foundation Interaction Subjected to Normal Faulting

2021 ◽  
Author(s):  
Fang Ru-Ya ◽  
Lin Cheng-Han ◽  
Lin Ming-Lang
Keyword(s):  
Active Fault ◽  
Ground Deformation ◽  
Numerical Models ◽  
Hanging Wall ◽  
Normal Fault ◽  
Small Scale ◽  
Foot Wall ◽  
Normal Faulting ◽  
Raft Foundation ◽  
Overburden Soil

<p>Recent earthquake events have shown that besides the strong ground motions, the coseismic faulting often caused substantial ground deformation and destructions of near-fault structures. In Taiwan, many high-rise buildings with raft foundation are close to the active fault due to the dense population. The Shanchiao Fault, which is a famous active fault, is the potentially dangerous normal fault to the capital of Taiwan (Taipei). This study aims to use coupled FDM-DEM approach for parametrically analyzing the soil-raft foundation interaction subjected to normal faulting. The coupled FDM-DEM approach includes two numerical frameworks: the DEM-based model to capture the deformation behavior of overburden soil, and the FDM-based model to investigate the responses of raft foundation. The analytical approach was first verified by three  benchmark cases and theoretical solutions. After the verification, a series of small-scale sandbox model was used to validate the performance of the coupled FDM-DEM model in simulating deformation behaviors of overburden soil and structure elements. The full-scale numerical models were then built to understand the effects of relative location between the fault tip and foundation in the normal fault-soil-raft foundation behavior. Preliminary results show that the raft foundation located above the fault tip suffered to greater displacement, rotation, and inclination due to the intense deformation of the triangular shear zone in the overburden soil. The raft foundation also exhibited distortion during faulting. Based on the results, we suggest different adaptive strategies for the raft foundation located on foot wall and hanging wall if the buildings are necessary to be constructed within the active fault zone. It is the first time that the coupled FDM-DEM approach has been carefully validated and applied to study the normal fault-soil-raft foundation problems. The novel numerical framework is expected to contribute to design aids in future practical engineering.</p><p><strong>Keywords</strong>: Coupled FDM-DEM approach; normal faulting; ground deformation; soil-foundation interaction; raft foundation.</p>

Dissipation of Alachlor in Four Soils as Influenced by Degradation and Sorption Processes

Weed Science ◽  
1994 ◽  
Vol 42 (2) ◽  
pp. 233-240 ◽  
Author(s):  
Pau Y. Yen ◽  
William C. Koskinen ◽  
Edward E. Schweizer
Keyword(s):  
Surface Soil ◽  
Sandy Loam ◽  
Soil Depth ◽  
Order Rate Constant ◽  
Silty Clay ◽  
Clay Loam ◽  
Corn Production ◽  
First Order ◽  
Degradation Data ◽  
First Order Kinetics

Laboratory studies were conducted to determine the influence of degradation and sorption processes on the dissipation of alachlor in one Colorado soil (Kim clay loam) and three Minnesota soils (Port Byron silt loam, Webster silty clay loam, and Estherville sandy loam) as a function of soil depth. Persistence and movement of alachlor in an irrigated corn production system also were determined on the Kim soil. Laboratory degradation data fit first-order kinetics, and rate constants ranged from 0.0094 to 0.0251 d-1and varied with soil type and depth. For instance, in 60- to 75-cm-depth Kim soil, alachlor degraded at a slower rate (k = 0.011 d-1) than in surface soil samples (k = 0.022 d-1). Alachlor sorption to the four soils was moderate (Kf= 0.7 to 7.4; Kf,oc= 71 to 470) and concentration dependent (1/n < 1.0). Significant hysteretic desorption of alachlor from soils also was observed (1/n desorption < 1/n sorption). The combined effect of degradation and sorption processes has been used to classify a chemical's potential to leach to groundwater. Based on Kf,ocand dissipation half-life, alachlor would be classified as a “leacher” in Kim, Port Byron, and Estherville soils and classified as transitional between “leacher” and “nonleacher” in the Webster soil. The dissipation first-order rate constant (k) of alachlor in Kim soil in the field was 0.036 α 0.012 d-1. Dissipation was apparently not due to leaching since bromide applied at the same time remained in the top 15 cm during the first 28 d. It appears that laboratory-derived leaching indices may overestimate actual leaching and should be used with caution for predictive or regulatory purposes.

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