bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monitoring of semi-permanent troughs and ridges in relation to monsoon
Authors: ASNANI G. C. , AWADE S.T. 
Published: February 2022

Two contrasting years (1967 and 1972) have been selected for intensive study in respect of large scale features of northern hemispheric contour field. In the present study, 700 and 300 mb mean monthly contours at different latitude circles at 5 degree interval, were subjected to Fourier analysis and horizontal and vertical tilts of troughs and ridges determined. At and north of 20°N, under quasi-geostrophic assumption, computations have been made to calculate meridional transports of momentum by tilted troughs and ridge at 700 and 300 mb levels and meridional transport of sensible heat at 500 mb level. The following chief results have been obtained.

(i) The differences in momentum transport during the two contrasting years were far more marked at 300 mb level than at 700 mb level.
(ii) In a year of good monsoon (1967), there was an anomaly of northward transport of momentum
across sub-tropical latitudes while in a year of poor monsoon (1972), there was anomaly of southward transport of momentum across the subtropical latitudes, at 300 mb level.
(iii) During a year of good monsoon (1967), there was anomaly of southward transport of sensible heat across the sub-tropical latitude of 30°N at 500 mb level, while in a year of poor monsoon (1972), the anomaly was in the form of northward transport.
(iv) The anomalies in the transports of momentum and sensible heat during 1967 and 1972 were perceptible about a month before the onset of monsoon over India. If this be true also for other years which have not been studied here, then there is a possibility of foreshadowing large-scale behaviour of the Indian monsoon one month or so ahead of the arrival of the monsoon.
(v) In terms of the anomalies in meridional transports or momentum and sensible heat across the sub-tropical latitudes, we present a model of abnormal monsoon in India. If the summer tropical atmosphere is warmer (cooler) than normal, the monsoon rainfall over India is likely to be more (less) than normal. This is shown to be in broad agreement with what is presently known about the theory of monsoon and observations of short-period anomalies in the behaviour of the Indian monsoon.
Temporal variations in the northern hemispheric summer circulations
Authors: UNNINAYAR MANAKKAMPAD S. , MURAKAMI TAKIO 
Published: February 2022

Changes in kinetic energy averaged over the tropical (5.0°S-19.6°N), subtropical (24.2°N-37.1 oN) and mid-latitude (41.0°N-48.1°N) belts were examined for the 92-day period from June through August 1970. Some-what systematic fluctuations (10-15 day period) were observed in the eddy and zonal mean kinetic energies of the 200 mb tropical belt. Mid-latitude periodicity was longer at about 20 days. Short period (~5 day) fluctuations were considerably stronger at 700 mb than that at 200 mb, over the tropical belt.
Abnormal transitions were observed to begin around 12 July with a simultaneous decrease in 200 mb eddy kinetic energy at all latitudes, 700 mb eddy kinetic energy over the tropical belt, and tropical baroclinic activity as determined from cloudiness; all reached minimum values around 20-24 July. On the other hand, tropical zonal mean kinetic energy increased to maximum values in the same period.
During 20-24 July, the tropospheric circulation displayed singularly different characteristics compared to normal, and break monsoon" conditions prevailed over India. The zones of cloudiness and upper divergence maxima over the monsoon region shifted northwards to the Tibetan area, while dry weather and abnormal upper convergent wind inflow was experienced over southeast Asia. A conspicuous and anomalous excitation of convective activity over 'tropical regions in the western North and South Pacific was associated with pronounced upper (lower) tropospheric anticyclonic (cyclonic) circulations. Consequently, 200 mb equatorial easterlies over the western and central Pacific were unusually strong. Concurrently the anticyclone over the Mexican region reached maximum intensity and was displaced to the north of its normal position
Need for intensified seismological studies in northeast India
Authors: SEN S. N. , ROY P. K. GUHA 
Published: February 2022

Of late there has been a keen awareness among scientists, the media and the general public about the vulnerability of NE India to major earthquakes, specially in view of the situation of this region at consumable plate boundaries (according to the Plate Tectonics Hypothesis), The seismological observatory in Shillong has been continuously recording the tremors felt in this region and determining their epicentres, many of which are on the plate boundaries in the Arunachal Himalayas and the Naga -Patko and Lushai ranges .The recent seismological studies by the Regional Research Laboratory at Jorhat ( Khazanchi et al, 1979) have indicated the possibility of a major earthquake in the region Within the decade of seventies, This has led to considerable public concern.
In view of the growing concern about an impending disaster it is imperative that the concerned agencies should take more active interest in seismological studies in this region.
As, far as Geological Survey of India (GSI) is concerned its basis function in an earthquake studies programme will include preparation of detailed structural an semiso-tectonico map or he region based on ground survey as well as aerial photo and satellite Imagery Interpretation, Identification of the active fault zones and then evolve some method of continuous monitoring of tremors and movements of the ground in these fault zones, In this task the. GSI would act in collaboration with the Seismological Observatory in Shillong of India Met. Dep., the Regional Research Laboratory In Jorhat as well, as the Earthquake Engineering Deptt. of Roorkee University.
Seismicity and tectonics in the Hindukush mountains, Sulaiman and Kirthar ranges in the light of plate tectonics theory.
Authors: VERMA R. K. , MUKHOPADHYAY MANOJ , BHANJA A. K. 
Published: February 2022

A seismicity map of the Pakistan-Afghanistan region that lies between the latitudes 280 & 380 N and longitudes 660 & 750 E is given using all available data for the period 1890-1972. The earthquakes of magnitude 4.5 and above were considered in preparation of this map. A strain-energy release map for the same period was prepared following the method used by Allen et al. (1965). On the basis of these two maps, it is observed that the seismicity pattern over the well-known Hindukush region is quite complex. Two prominent mutually orthogonal seismicity lineaments, namely, the northwestern and the northeastern trends characterize the Hindukush area. The northwestern trend appears to extend from the Main Boundary Fault of the Kashmir Himalaya on the southeast to the plains of the Amu Darya in Uzbekistan on the northwest beyond the Hindukush. The Sulaiman and Kirthar ranges of Pakistan are well defined zones of intermontane seismicity exhibiting north-south alignment.
Thirty-two new focal mechanism solutions for the above mentioned region have been determined. These, together with the results obtained by earlier workers suggest the prevalence of thrust as well as strike-slip faulting in the area. The Salt range; the Sulaiman wrench zone, the Kirthar wrench zone as well as the supposed extension of the Murray ridge upto the Karachi coast appear to be mostly undergoing strike-slip movements. In the Hindukush region, thrust as well as strike-slip faulting are found to be equally prevalent. Almost all the thrust type mechanisms belonging to the Hindikush area have both the nodal planes in NW-SE direction for shallow as well as intermediate depth earthquakes. The dip of F-axes for the events indicating thrust type mechanisms rarely exceeds 35°. The direction of seismic slip vector obtained through thrust type solutions is always directed towards the northeast. The epicentral pattern together with these results suggest a deep-seated fault zone paralleling the northwesterly seismic zone underneath the Hindukush. This NW-lineament has a preference for thrust faulting, and it appears to extend from the vicinity of the Main Boundary Fault of the Kashmir Himalaya on the southeast to Uzbekistan on the northwest through the Hindukush. Almost perpendicular to this NW-seismic zone, there is a NE-seismic lineament in which there is a preference for strike-slip faulting.
The above results are discussed in the light of convergence between the Indian and predicted by plate tectonics theory.
Temporal and spatial variation in seismicity connected with few earthquakes in Himalayas as precursor to earthquakes
Authors: DUBE R.K. , CHATTERJEE S.N. 
Published: February 2022

. Experiments made on rock samples in laboratory and rock bursts in mines (Brady 1975, 1976) have shown that four phases. viz., dilatant; inclusion, crack closure and finally failure. precede fault growth. These behavioural phases have been found to be scale invariant and thus find application to earthquake processes. Spatial and temporal variations of seismicity in the aftershock area of seven earthquakes, within magnitude (Mb) range of 5 to 6.2, which took place in Himalayas, have been observed and the above concept has been used for earthquake prediction. Empirical relations have been obtained to predict the magnitude and time of occurrence of an
impending earthquake.
Some quantitative seismicity studies in north India Including Kutch
Authors: CHOUHAN R. K. S. 
Published: February 2022

Strain release characteristics of various regions of India have been studied by dividing the northern India from Assam to Kashmir into three regions and taking Kutch as the fourth region, Strain accumulation and relaxation curves have been prepared showing the maximum and minimum strain levels except for the Bihar-Nepal region, From these curves store of
strain available to be released In future earthquakes have been estimated.
Predicting earthquakes through space
Authors: ZADGAONKAR A.S. , TARNEKAR M.G. 
Published: February 2022

Out of the several reason that are responsible for an earthquake, one seems to be interesting .The comparison of ground water-level (Tashkeni, U.S.S.R.) and the date of earthquake shown a close relation ship between the rise of the water level and the earthquake. The device, transistorized rain predictor designed by the authors is capable of giving prediction of ground water-level at the place of observation about one week in advance .It is felt that if such information is obtained at place of frequent possibility of quakes associated with a sudden rise of ground water-level ,it would be possible to have an earthquake prediction about one week in advance. Such an advance information can always be helpful in saving the lives in the affected area and/ or to start the relief activities which may be planned effectively well in advance rather than having them after the end of the calamity.
Spatial prediction of earthquakes in the Kumaon Himalaya By pattern recognition
Authors: ODAY VARUN , GAUR V. K. , WASON H. R. 
Published: February 2022

The work presented relates to a pattern recognition study of the Kumaon Himalaya to delineate dangerous and non-dangerous Zone using a priori knowledge of some strong earthquakes that occurred in the region. The raw data incorporates various geological parameters and processed to extract distinctive dangerous and non-dangerous features.
Prediction of the magnitude of an earthquake from foreshocks
Authors: VARMA G.S. 
Published: February 2022

Largest foreshock versus main shock studies have been done for different regions from different earthquake sequences .The study shown that this correlation is positive for sight to moderate earthquake and negative for moderate to great earthquake. Nepal-India border region gave a negative correlation through out. The study therefore reveal that the foreshock activity is generally confined to moderate earthquakes while the great earthquakes are free from such an activity. Great events will occur quiescently in this sub-continent and the foreshock activity in their case will be beyond our detection capability.
Mathematical relations have been computed and a nomogram has been prepared for each region by which the magnitude of an earthquake can easily be predicted.
Existence of the dilatancy phenomena in the Assam region
Authors: SINGH V. P. , GUPTA HARSH K. 
Published: February 2022

In accordance with the dilatancy model for earthquakes, P-wave velocity decreases in the source and region during the precursor time, and consequently the mean, teleseismic P-wave travel-time residual at a station earthquakes close to the source should increase, We have analysed teleseisemic P-wave travel-time data at Shillong for the period from October 1964,through March 1974. The total number of events is 8021 including 1502 events with focal depths> 100 km, Six monthly average residuals have been calculated for the considered period. For the averaging period, the standard deviations are found to be less than 0.15 sec. This indicates that the residuals of the order 0.3 sec could be detected in the average P-wave residual histograms, the 1 June 1969 earthquake of Mb=5.0, at a distance of 20 km is well ref1ected. The outstanding feature of the six monthly average residuals is that the P-wave velocities have decreased since 1969 and it appears that the Assam region is presently experiencing a precursory dilatancy stage.
Temporal variations of tS /tP ratios before and after Koyna earthquake of 10 December 1967 and calculation of its magnitude
Authors: SARMAH S. K. , SHABONG E. 
Published: February 2022

An analysis of the body wave travel time ratios (tS /tP) has been made for four seismographic stations Koyna Nagar, Satara, Mahabaleswar and Pune-from 24 October to 15 December 1967. The arrival times of body waves in different stations have been taken from published reports on Koyna Earthquakes. Origin times of the fore-shocks and aftershocks of the main Koyna earthquake of 10 December 1967 (M =6.2) have been calculated from the plots of S-P intervals and P arrival times at different stations. A plot of tS / tP ratios against time shows the anomalous variation of the ratio with a fall of about 10 to 14 % from the mean values for the period under consideration in Koyna Nagar, Satara and Mahabaleswar. No such tS/tP variations have been observed in Pune, which shows more or less steady values. The time interval, which we call anomalous period, from the date of fall of tS/tP from the mean value upto the time of occurrence of the main shock on 10 December 1967 is 32 days in each station. this anomalous period seems to coincide with the reported sharp and simultaneous changes indicated by some strain gauge placed in Koyna Dam, for about a month prior to the occurrence or the main Koyna earthquake. On using empirical relations based on dilatancy-fluid diffusion model, this amount of anomalous period is equivalent to that of a smaller shock of magnitude between 4 and S. Consideration of aftershock area coupled with other empirical relations also indicates similar magnitude.
These facts tend to suggest either (1) the empirical relations used here do not hold good for Koyna earthquake or, (2) a smaller shock of magnitude between 4 and 5, occurring just ahead of the main shock, gave rise to tS /tP anomalies.
A note on the anomalous tilt preceding the Koyna earthquake Of 10 December 1967
Authors: RAO P. SITAPATHI , BHATTACHARYYA N. , RAO B. RAMALINGESWARA 
Published: February 2022

Employing the tiltgraph data of the Koyna Dam Observatory published in the reports of the Central Water and Power Research Station, Khadakwasla, Pune (1970), weekly mean value of the daily variation or the tits has been computed for a period of six months starting from November 1967 to March 1968 which covers the main shock of 10 December 1967 and its aftershocks.
A plot of the weekly means on the time scale gives a systematic change in tilt and cloys finally (a high value of 1.2 micro radians in this case) preceding the earthquake. Further it abruptly reverses by 180° in its direction about two weeks prior to the major shock, which may be considered a precursor. The analysis and the results obtained thus are discussed for the 10 December 1967 earthquake and its aftershocks in the Koyna region.
Use of Kazakh nuclear explosions for testing dilatancy diffusion model of earthquake prediction
Authors: SRIVASTAVA H. N. 
Published: February 2022

P-wave travel time anomalies from Kazakh explosions during the years 1965-1972 were studied with reference to Jeffreys Bullen (1952) and Herrin Travel time tables (1968) and discussed using F ratio It test at seven stations in Himachal Pradesh. For these events, the temporal and spatial variations of travel time, as residuals were examined from the point of view of long-term changes in velocity known to precede earthquakes and local geology.
The results show preference for Herrin Travel time tables at these epicentral distances from Kazakh explosions. F ratio test indicated that variation between sample means of different stations in the network showed more variation than can be attributed to the sampling error. Although the spatial variation of mean residuals (1965-1972) could generally be explained on the basis of the local geology, the temporal variations of such residuals from Kazakh explosions offer limited application in the testing of dilatancy model of earthquake prediction.
Recent seismic activity in Delhi and neighbourhood
Authors: KAMBLE V.P. , CHAUDHURY H. M. 
Published: February 2022

In ordert o assess the seismic status of existing faults burried under thickalluvial deposits in the plains around Delhi, a tot al of 937 recorded shocks have been analysed. The spatial and temporal distibut ions of earthquakes and strain release pat terns have been discussed with reference1 the positions and trends of the existing fault pat tern s. The value of slope coefficient h was found to decrease before and increase just after the major events.
P wave travel times from Nevada nuclear explosions and station corrections
Authors: GUPTA A. K. , GOGNA M. L. , CHOPRA S.D. 
Published: February 2022

One hundred fortynime Neva a explosions have been studied .These explosions a more than ten thousands observations. Travel til11es of P-waves have been obtained. These times are more than J. B. P-times for . For all other distances they are less than J. B. P-times. The maximum difference is -2.70 second at 33° epicentral distance. Station corrections for most of the observing stations have also been calculated. These station corrections have been compared with the work of the other authors. The calculated station corrections are in good agreement with the ones obtained by other people for most of the stations. There are significant differences at some stations.
On stress accumulation near a finite rectangular fault
Authors: PAL BARUN PROSAD , SEN SANJAY , MUKHOPADHYAY ARABJNDA 
Published: February 2022

The problem of stress accumulation near a locked vertical rectangular strike-slip fault is considered. The fault is taken to be situated in a visco-elastic half-space. It is assumed that tectonic forces maintain a steady shear stress far away from the fault. Exact solutions are obtained for the displacements and stresses in the system and it is shown that, in the absence of fault-slip, there would be a steady accumulation of shear stress near the fault., which would lead to a sudden slip on the fault, resulting in an earthquake, under suitable conditions, which are determined. The exact solutions also show that the accumulation of shear stress would again take place after the fault-slip.
It is shown that, under suitable conditions, this would lead to another slip on the fault after a sufficient time. The analytical solutions can be used to compute the influence of different factors, such as, the dimension of the fault, the effective viscosity of the lithosphere and the stress system maintained by tectonic forces, on the time required for the shear stress accumulation to reach the level necessary to cause fault slip. It is also shown that, if adequate data are available on the ground deformation on the surface near the fault, it would be possible to obtain estimates of the probable times of fault slip. This may be of considerable use in earthquake prediction and in the estimation of changes in the seismic risk near the fault with time. Finally, it is shown that it would also be possible to obtain estimates of the effective viscosity of the lithosphere from a comparison of theoretically calculated results and suitable observational data, if available.
The effect of changing-elasticity on the stress concentration near a semi-infinite crack tip
Authors: VISWANATHAN K. 
Published: February 2022

One of the very convincing premonitory changes in earthquake predictions concerns the variation of the velocity ratio (Vp/Vs) preceding the occurrence of the event. The aim of the present investigation is to construct a, the radical basis to evaluate the consequences of such changes on, say, the stress concentration near an already existing fault with a given static initial field. The change in elasticity is assumed over a limited part of the where the medium near the fault.
SH waves across a column sandwiched in an inhomogeneous medium
Authors: KUMARI UMESH 
Published: February 2022

The propagation or love waves across a vertical column sandwiched in a medium of different properties has been studied, Three different models are considered: (i) an infinite column in a semi-infinite medium, (ii) a column in a layer resting over a rigid bottom and (iii) a column in a layer resting over a semi-infinite elastic medium in welded contact with it. In each case the elastic properties vary vertically but this variation is the same both inside outside the column. Frequency equations have, been obtained for the regions inside and outside the column and dispersion curves drawn. As expected the wave periods change as the waves pass into and out of the column .Displacements in these regions have been obtained and presented graphically for points in the free surface .Reflection and transmission coefficients for normal Incidence at vertical discontinuities have also been obtained.