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H. N. Singh ¹, P. V. Panchanathan ¹, K. R. Unnikrishnan ¹

Affiliations
1 Centre for Earth Science Studies, Trivandrum 695 010, IN

Abstract

Forty-one gravity bases were established with a Worden gravimeter in parts of Palghat gap area bordering Kerala and Tamil Nadu. The description of these base stations and the observed gravity values are presented. The observed gravity values at these stations are with reference to a value of 978.0715 gals at the Coimbatore Airport, established by the National Geophysical Research Institute, Hyderabad. The accuracy of the observed gravity values is estimated to be 0.07 mgal. The new base stations are being used for regional gravity surveys.

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Harsh K. Gupta ¹, Kusala Rajendran ¹, H. N. Singh ¹

Affiliations
1 Centre for Earth Science Studies, Trivandrum 695 010, IN

Abstract

The north-east India region is seismically one of the most active regions In the world. An earthquake data base for the region from the earliest time to 1984 is presented here. These data would be utilized for investigating the earthquake phenomenon in the region.

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Harsh K. Gupta ¹, H. N. Singh ¹

Affiliations
1 Centre for Earth Science Studies, Trivandrum 695 010, IN

Abstract

Since 1897, ten earthquakes of M ≥ 7½ have occurred in north-east India region and its vicinity including the great earthquakes of June 12, 1897 and August 15, 1950, both of M 8.7. The last earthquake belonging to this category, occurred on August 17, 1952. With the exception of three earthquakes, others are found to be associated with the epochs of background/normal seismicity, precursory swarm, quiescence and mainshock (and the associated foreshocks and aftershocks). In our investigations, the earthquake data have been critically examined and taking due care of prevalent location - capabilities and other parameters. The mainshock magnitude (M_m) is related to the magnitude of the largest events in the swarm (̅M_p) and the time interval T_p (in days) between the beginning of the swarm and the main shock. The regression equations are:

                                 M_m = 1.37  ̅M_p - 1.41

and                            Mm = 3 log₁₀ T_p - 3.27

Installation of the World Wide Standard Seismograph Network during 1962-63 improved the earthquake detection and location capabilities considerably in the northeast India region and all earthquakes of m_b ≥ 4.5 are being located. Consequently, for the period 1963 through 1985, we have investigated all events of m_b ≥ 6.1 for occurrence of precursory swarms. Ten such events have occurred, four of which in a quick succession in the Arakan Yoma fold belt within a time span of six months only, and constitute a well defined swarm. Two other earthquakes are possibly gap events of Arakan Yoma swarm. Out of the remaining four, three are found to be associated with epochs of normal/background seismicity, precursory swarm, quiescence and main. shock (and the associated foreshocks and aftershocks). The latest killer earthquake in northeast India of Dec. 30, 1984 of m_b 5.6, which occurred in the vicinity of the Arakan Yoma fold belt and Shillong Plateau, was preceded by a well-defined precursory swarm and seismic quiescence.

The most important thing is to recognize the precursory swarms and quiescence in real time, before the occurrence of the main shock. We believe to have recognized one such sequence in the vicinity of Arakan Yoma fold belt. On the basis of M_p and T_p values, lateral extent of the swarm activity and the fact that no event of m_b ≥ 6.1 has occurred since 1975 in the preparation zone defined by the 1963-65 swarm, we estimate that an earthquake of M 8 ½ could occur any time from now in an area bound by 21°N and 25½°N latitudes and 93°E and 96°E longitude, with a focal depth of 100±40km.

We have also recognized a region in Eastern Syntaxis where repeated swarms have occurred during 1968, 1977 and 1980. The largest events in these swarms, however, were only of m_b 5 and the swarms were very localized. These may have been caused by magmatic emplacement at shallow crustal depths.

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H. N. Singh ¹, Venkatesh Raghavan ¹

Affiliations
1 Centre for Earth Science Studies, P. B. No. 7250, Trivandrum 695031, IN

Abstract

No Abstract.

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H. N. Singh ¹, Venkateash Raghavan ¹

Affiliations
1 Centre for Earth Science Studies, Trivandrum 695 031, IN

Abstract

No Abstract.

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G. K. Raju ¹, K. R. Unnikrishnan ¹, H. N. Singh ¹, K. Vijayakumar ¹

Affiliations
1 Centre of Earth Science Studies, Trivandrum, IN

Abstract

No Abstract.

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Surendra Singh ¹, H. N. Singh ¹

Affiliations
1 Department of Chemistry, Aligarh Muslim University, Aligarh-202 001, IN

Abstract

Solubilization of aminoazobenzene-beta-naphthol (Sudan III) and orthotoluene-azo-orthotoluene-azo-beta naphthol (Sudan IV) dyes in anionic, cationic, and nonionic micelles in aqueous medium, have been studied spectrophotometrically at 30°C. The absorbance of either of the solubilized dye in dilute surfactant solutions does not change appreciably. But it was found to vary linearly with surfactant concentration above the CMC. Comparable solubilities of dyes in concentrated solutions of surfactants and in organic solvents provide some indication about the location of the solubilizate in the micelle interior. For a particular dye-surfactant system, moles of surfactant solubilizing a mole of dye, N_D, have been calculated from the straight live portions of the plots. N_D has been found to depend on the nature of the surfactant and the structure of dye. Decreased values of N_D with increased chain length of added alkanols have been explained in the light of partitioning of alcohol at the micelle water interface. Lower values of standard free energy of solubilization indicate smaller hydrophobic contribution in the solubilization process. The mechanism of solubilization has been found to depend on the nature of solubilizer, solubilizate, and the additives.

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Sanjeev Kumar ¹, Surendra Singh ¹, H. N. Singh ¹

Affiliations
1 Department of Chemistry, Aligarh Muslim University, Aligarh-202 001, IN

Abstract

In the present study, observations and data on the formation and characterization of water-in-oil (W/o) microemulsion systems composed of a cationic surfactant (Cetyltrimethylammoniumbromide)-water-alkanes (C₆-C₇) 2-ethyl-1-hexanol have been reported. The influence of the alkane chain length on the formation of microemulsion systems has been investigated. When the amount of oil or water was increased, the appearance of microemulsion changed from clear to bluish to turbid. These transitions were indentified on the basis of both resistance measurement and visual appearance. Changes in specific resistance with water composition were interpreted in terms of water inforced-micellar structural changes. The critical moles of water/mole of oil ratio, Vc values, at which the microemulsion remains stable, was calculated from viscosity measurements. The linear dependence of Vc values on the number of carbon atoms in the alkyl chain of oil has been reported for predicting the size of the chain length of oil for the formation of a wide range of stable W/o microemulsions. The standard free energy change for transfer of cosurfactant from oil phase to the interfacial phase is also reported.

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Surendra Singh ¹, Sanjeev Kumar ¹, H. N. Singh ¹

Affiliations
1 Department of Chemistry, Aligarh Muslim University, Aligarh 202001, IN

Abstract

The interaction between thiaminehydrochloride, ThmHCl (Vitamine B₁) and sodium salts of long chain alkyl sulfates, SAS (C₈, C₁₀, and C₁₉,) has been studied in aqueous solution. Conductimetric titration of thiaminehydrochloride with surfactant resulted three distinct regions. Region I and II where complexation, precipitation and separation occurs were of much interest and were investigated in detail. Values of ion-pair association constants and their dependence on surfactant alkyl chain length were determined by standard method. Standard free energy of ion-pair formation was determined for all the three surfactants in the region I. The 1:1 solubility product, and its dependence on surfactant alkyl chain length was determined for region II. Addition of surfactant solution above the critical micelle concentration resulted in the dissolution of the complex forming a clear solution, region III.

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H. N. Singh ¹, Sanjeev Kumar ¹

Affiliations
1 Department of Chemistry, Aligarh Muslim University, Aligarh 202002, IN

Abstract

Ternary phase diagrams for the system sodiumdodecylsulphate (SDS)-n-pentanol-water-benzene in the presence of sodium chloride have been produced at 25°C. The phase diagrams show existence of various phases as a result of variation of composition of components. The effect of [NaCl] on various phase regions of the phase diagrams was studied in the light of structural changes and inversion of phases. Various overall compositions were chosen within the clear homogeneous regions and the effect of NaCl concentration was studied on phase separation and phase volumes of various phases. The nature of the separated phases has been also described. The existence of various microstructures in the isotropic single phase region 'L' at a number of compositions of the system was detected by conductivity measurements simply by varying the concentration of water and/or benzene.

Keywords

Microemulsion, Phase Diagram, Microstructure, Surfactant, Micelle.

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H. N. Singh ¹, Venkatesh Raghavan ¹, A. K. Varma ¹

Affiliations
1 Centre for Earth Science Studies, Trivandrum 695 031, IN

Abstract

The epicentres of Idukki earthquake sequence of 7th-8th June 1988 which was widely felt in southern peninsular India, has been investigated. They are confined to a small area around 9°48'40" N and 77°11'10"E. A maximum Intensity VI on the MM scale has been assigned in the epicentral region of the main shock. Magnitudes of 4.5, 4.1 and 3.4 have been estimated based on signal duration for the main shock and two significant aftershocks respectively. The studies carried out have indicated that the earthquake is associated with major lineaments. Possibility of earthquake being triggered by the Idukki reservoir is remote.

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K. P. Pandeya ¹, S. B. Singh ¹, H. N. Singh ¹

Affiliations
1 G.S. Sugarcane Breeding and Research Institute, Deoria - 274407, U.P., IN

Abstract

Field surveys were conducted during the year 1990-91 to record the natural enemy complex of sugarcane top borer in Deoria district of Uttar Pradesh. Affected cane tops were collected from sugarcane field having different stages of parasitised and healthy egg- masses, larvae and pupae of Scirpophaga excerptalis and kept in specimen jars covered with fine muslin cloth at 28 ± 2°C and 65 ± 5% RH for the emergence of natural enemies. The natural enemies emerged were preserved and identified by .Commonwealth Institute of Entomology, United Kingdom.

Keywords

Scirpophaga excerptalis, Parasitoids.

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