Surface displacement estimation along Himalayan frontal fault using differential SAR interferometry

The Himalayan region has been studied extensively during the past few decades in terms of present ongoing deformations. Various models have been proposed for the evolution of the Himalaya to explain the cause of earthquake occurrences and to understand the seismotectonics of the Himalayan collision zone. However, the information on displacements from field geodetic surveys is still too scarce in time and spatial domains so as to provide convincing evidences. Moreover, classical Probabilistic Seismic Hazard Approaches also fail due to paucity of data in higher magnitude range, thus emphasizing the need of spatial level displacement measurements. It is in this context that the present study has been carried out to estimate the surface displacement in a seismically active region of the Himalaya between Ganga and Yamuna Tear using Differential SAR interferometry. Three single-look complex images, obtained from ASAR sensor onboard ENVISAT satellite, have been used. A displacement rate of 8?C10?mm per year in N15°E direction of Indian plate has been obtained in this three-pass SAR interferometry study. It has been noted that the estimated convergence rate using Differential SAR interferometry technique is relatively low in comparison with those obtained from previous classical studies. The reported low convergence rate may be due to occurrence of silent/quite earthquakes, aseismic slip, differential movement of Delhi Hardwar ridge, etc. Therefore, in view of the contemporary seismicity and conspicuous displacements, a study of long-term observations of this surface movement has been recommended in future through a time-series SAR interferometry analysis.     

Assessment of Chock Capacity and Strata Caving for a Longwall Mine

A mine scale numerical analysis of modern day longwall using a 3D Cosserat continuum method has been presented. The effect of mine specific geological conditions on viability of introducing a modern day longwall is comprehensively investigated and analysed in this paper. The various longwall parameters like chock (face support) convergence and strata caving mechanism are evaluated. The varying thickness of the sandstone present in the roof can be seen to have a strong impact on the magnitude and pattern of chock convergence. The paper also discusses the performance of chocks with different capacities under identical conditions. The effect of overlaying sandstone properties and width of the longwall panels have also been investigated. The analyses carried out in this study is expected to provide valuable process guidance during the mine design in relation to selecting the optimal mine geometry and support capacity so that the potential mining hazards could be minimized.     

Variability of Indian monsoonal rainfall over the past 100 ka and its implication for C3–C4 vegetational change

Oxygen and carbon isotope ratios of soil carbonate and carbon isotope ratios of soil organic matter (SOM) separated from three cores, Kalpi, IITK and Firozpur, of the Ganga Plain, India are used to reconstruct past rainfall variations and their effect on ambient vegetation. The δ¹⁸O values of soil carbonate (δ¹⁸O_SC) analyzed from the cores range from ? 8.2 to ? 4.1‰. Using these variations in δ¹⁸O_SC values we are able, for the first time, to show periodic change in rainfall amount between 100 and 18 ka with three peaks of higher monsoon at about 100, 40 and 25 ka. The estimation of rainfall variations using δ¹⁸O value of rainwater-amount effect suggests maximum decrease in rainfall intensity (~ 20%) during the last glacial maximum. The δ¹³C values of soil carbonate (δ¹³C_SC) and SOM (δ¹³C_SOM) range from ? 6.3 to + 1.6‰ and ? 28.9 to ? 19.4‰, respectively, implying varying proportions of C₃ and C₄ vegetations over the Ganga Plain during the last 100 ka. The comparison between monsoonal rainfall and atmospheric CO₂ with vegetation for the time period 84 to 18 ka indicate that relative abundances of C₃ and C₄ vegetations were mainly driven by variations in monsoonal rainfall.     

Application of soft computing in predicting rock fragmentation to reduce environmental blasting side effects

In the blasting operation, risk of facing with undesirable environmental phenomena such as ground vibration, air blast, and flyrock is very high. Blasting pattern should properly be designed to achieve better fragmentation to guarantee the successfulness of the process. A good fragmentation means that the explosive energy has been applied in a right direction. However, many studies indicate that only 20–30 % of the available energy is actually utilized for rock fragmentation. Involvement of various effective parameters has made the problem complicated, advocating application of new approaches such as artificial intelligence-based techniques. In this paper, artificial neural network (ANN) method is used to predict rock fragmentation in the blasting operation of the Sungun copper mine, Iran. The predictive model is developed using eight and three input and output parameters, respectively. Trying various types of the networks, it was found that a trained model with back-propagation algorithm having architecture 8-15-8-3 is the optimum network. Also, performance comparison of the ANN modeling with that of the statistical method was confirmed robustness of the neural networks to predict rock fragmentation in the blasting operation. Finally, sensitivity analysis showed that the most influential parameters on fragmentation are powder factor, burden, and bench height.     

The nature and engineering behavior of carbonate soils at Bombay High,India

Abstract

This paper presents the results of a laboratory investigation undertaken to study the nature of two submarine carbonate soils from Bombay High off the west coast of India, as well as to study the shear and plasticity behavior of their sand and silt‐clay fractions, respectively. Scanning electron micrographs reveal that the carbonate content in both soils is comprised primarily of nonskeletal particles of various types. X‐ray diffraction and infrared absorption analyses indicate that in one soil the carbonate fraction consists of calcite and aragonite minerals, whereas in the other soil dolomite is also present. The non‐carbonate fraction of both soils is comprised primarily of quartz and feldspar, and also some clay minerals. The nature of the carbonate fraction of the two soils indicates that they were formed by different depositional processes.

During drained triaxial shear the nonskeletal sand grains of both soils exhibit a lower degree of crushing when compared with that of the skeletal carbonate sands, and thus appear to be stronger foundation material.

Although the carbonate contents of the silt‐clay fractions of the two soils are similar, they exhibit markedly different plasticity characteristics . This is probably because of the microlevel cementation produced by carbonate material in one soil.

This study leads one to the conclusion that carbonate content alone should not be treated as a parameter which controls the engineering behavior of submarine soils; the nature and form of carbonate material must also be identified.     

A record of ductile syn-intrusional fabrics to post solidification cataclasis: Magnetic fabric analysis of neoproterozoic Mirpur and Mt. Abu Granitoids,NW India

The Mirpur granite body represents a relatively small (10 km²) pluton intruded along the northern margin of the adjacent Mt. Abu batholith (∼125 km²) in NW India. It is a visibly undeformed alkali feldspar rich pink granite; in contrast, the Mt. Abu is a composite granitoid body and variably deformed. Both are intruded by rhyolitic dykes and the terminal magmatic events in both the cases are mafic dykes. The AMS (Anisotropy of Magnetic Susceptibility) data identify the Mt. Abu with SE-dipping foliations and subvertical lineations as a single structural domain while the Mirpur granite body shows two domains characterized by predominantly E — W trend of magnetic foliation in the eastern part (domain I) and N — S orientations in the western part (domain II). The domain I shows magmatic fabrics, typical for the peraluminous granites of Malani Igneous Suite (MIS). Change in fabric orientation in the domain II has resulted from cataclasis wherein the samples show destruction of the original E — W fabric and complete transposition by N — S trends. The foliations in the Mt. Abu granites have been related to SE orientation of maximum horizontal stress. The same maximum stress direction can be inferred from dyke orientation in the Mirpur granite, which is interpreted as continuation of the tectonic imprint in this region during emplacement of both the granites. Age of the cataclastic overprint with a predominant N — S orientation is not yet constrained but corresponds with the trend of the nearby Sindreth basin within the Malani Igneous Suite. The Neoproterozoic tectonic scenario for the region has been interpreted in terms of an ongoing crustal convergence and granitic magma emplacement against the back stop offered by the rigid Delhi Fold Belt.     

Relationship between earthquake swarm,rifting history,magmatism and pore pressure diffusion — an example from South Andaman Sea,India

An extraordinarily strong and persistent earthquake swarm (Andaman swarm 2005) originated in the Andaman back-arc following the aftershock sequences of the 26 December 2004 Sumatra earthquake. The swarm (n = 651, mb_max= 5.9) came mainly in two phases: January 26–31 and Feb.–Aug. 2005, in an area of size 90 × 40 km², at the centre of which lies a broad bathymetric depression and high gravity zone. The swarm demonstrates a complex faulting series, initially the strike-slip motion followed by normal faulting in repetitive sequences, whose representative fault planes orient at high angle to the regional faults. The swarm character as well as the distribution of stress-axes and their correlation to tectonic features lends speculation for formation of a nascent rift segment in NW-SE direction at the doorstep of the Sewell Seamount. The swarm has given rise to 21 episodes of rifting activities of variable time extent within 26–31 January 2005. The r-t plots corresponding to the swarm data, modelled with variable hydraulic diffusivity (D) values 4, 6, 8 and 10 m²/s, suggest for excess pressure front from ascending magmatic fluid. This eventually heralded the rifting; causing pore pressure perturbations that propagated in accordance with known diffusion parabolic equations.     

Landslide susceptibility zonation of the Chamoli region, Garhwal Himalayas, using logistic regression model

A remote sensing and Geographic Information System-based study has been carried out for landslide susceptibility zonation in the Chamoli region, part of Garhwal Himalayas. Logistic regression has been applied to correlate the presence of landslides with independent physical factors including slope, aspect, relative relief, land use/cover, lithology, lineament, and drainage density. Coefficients of the categories of each factor have been obtained and used to assess the landslide probability value to ultimately categorize the area into various landslide susceptibility zones; very low, low, moderate, high, and very high. The results show that 71.13% of observed landslides fall in 21.96% of predicted very high and high susceptibility zone, which in fact should be the case. Furthermore, lineament first buffer category (0–500 m) and the east and south aspects are the most influential in causing landslides in the region.     

Utilization of Banana Stem Juice as a Feedstock Material for Bioethanol Production

Bananas are widely cultivated in tropical and subtropical countries and about 220 tons of biomass waste is produced per hectare of banana plantation. Banana pseudostem contains nearly 90% of moisture and about 4–5 m³ sap is generated from one ton of dried stem with high chemical oxygen demand(COD) and biological oxygen demand (BOD). The feasibility of using banana sap as a feedstock to produce ethanol is evaluated in this study. Banana sap is obtained by crushing the pseudostems and concentrated ten times and supplementing with other industrial byproducts such as corn steep liquor(CSL), spent wash (SW), and yeast extract (YE) for ethanol production. Acid and alkali hydrolyzes are performed to enhance the sugar levels of the sap before fermentation. Two different strains of Saccharomyces cerevisiae (MTCC170 and MTCC180) are used for fermentation. In general, supplementation of banana sap with industrial byproducts significantly enhanced the ethanol production. The maximum ethanol production (2.5 g ^?1) is observed with concentrated banana sap supplemented with 25% SW (v/v) with MTCC170, which is 16‐fold higher than banana sap alone. Theethanol content is also higher in alkali‐hydrolyzed banana sap supplemented with 25% SW compared to control. These results suggest that banana sap can be used as a renewable source to produce ethanol by supplementing with other industrial byproducts.