Simulation of near-field ground motion characteristics of May 01, 2013, Doda earthquake using modified semi-empirical approach     

Rajaram Chenna  Pradeep Kumar Ramancharla 《Natural Hazards》2016,82(2):1411-1430

  相似文献   

Crustal Magnetic Studies over Krishna-Godavari Basin in Eastern Continental Margin of India     

Mita Rajaram  S.P. Anand  Vinit C. Erram 《Gondwana Research》2000,3(3)

Total field magnetic data were collected over the Krishna-Godavari basin covering 20, 000 sq.km with an average spacing of 8.5 km. This was mainly to study the long wavelength features related with the deep structures. Aeromagnetic map of the region compared well with the ground maps. The anomaly maps show a combination of NE-SW, NS/NNE-SSW and NW-SE trends. The anomalies of ground data are transformed to isolate the sources at different depths. The second vertical derivative and downward continuation maps bring out clearly the NE-SW and NS/NNE-SSW trends related to the coastal basin and Eastern Ghats implying that they are shallow. These are probably superposed on much deeper NW-SE trending structural features of Pre-Gondwana breakup as evidenced in the Horizontal Gradient of Pseudogravity and upward continuation maps. From the offshore magnetic data it appears that these trends extend up to the Ocean Continent Boundary. It is inferred that the deeper features are associated with rifting of Dharwar and Bastar cratons within the Indian plate, prior to the rifting of India from Gondwanaland. The superposed horst and graben structures are related to the formation of the pull-apart Krishna-Godavari basin as a result of rifting and drifting of India from Gondwanaland. These two structural features are associated with two different tectonic events.  相似文献   

Book review     

Rajaram Krishnaraj 《Journal of the Geological Society of India》2014,84(3):370-371

  相似文献   

Anthropogenic influences on toxic metals in water and sediment samples collected from industrially polluted Cuddalore coast,Southeast coast of India     

K. Mathivanan  R. Rajaram 《Environmental Earth Sciences》2014,72(4):997-1010

The present study was carried out to investigate the impact of anthropogenic influences on Cuddalore coast, Southeast coast of India, with regard to physicochemical parameters and heavy metal concentration in the surface water and sediment samples of the study area. The samples were collected in different seasons of the year (January–December 2010) and analysed for physicochemical parameters (Temperature, pH, salinity, nitrate, nitrite, ammonia, phosphate and silicate) and heavy metals (Cd, Cu, Pb and Zn) using standard methods. Results showed that physicochemical characteristics and heavy metals concentration in the samples of the study area were varied seasonally and spatially. The concentrations of heavy metals in water and sediment samples of the study area were higher in the monsoon season compared with those of other seasons. The heavy metal concentration in collected samples was found to be above WHO standards. The order of heavy metals in water and sediment samples was Pb > Cu > Cd > Zn. The heavy metal data were analysed through widely using multivariate statistical methods including principle component analysis (PCA) and cluster analysis (CA). CA classified the sampling sites into three clusters based on contamination sources and season. The PCA revealed that the season has a huge impact on the levels, types and distribution of metals found in water and sediment samples. The study also shows the main basis of heavy metals pollution at Cuddalore coast is land based anthropogenic inputs as a result of discharging of waste from industries, municipal, agricultural activities and sewage into estuarine regions, which carries the wastes into coastal area during tidal action. Statistical analyses and experimental data revealed that the Cuddalore coast may cause health risk to the recreational users and fisher folk, ultimately warrants environmental quality management to control heavy metal contamination.  相似文献   

Energy dependence of near-relativistic electron spectrum at geostationary orbit during the SEP events of 2005     

A. Chandrasekhar Reddy  Jatin Rathod  Girija Rajaram  Radharani Alyana  D. S. Misra  C. G. Patil  M. Y. S. Prasad  A. G. Ananth 《Journal of Astrophysics and Astronomy》2008,29(1-2):313-317

In view of the renewed interest in the study of energetic particles in the outer radiation belt of the earth, we feel it will be helpful in looking for the energy dependence of the electron energy spectrum at geostationary orbit. This may give us some insight into how we can safeguard geostationary satellites from functional anomalies of the deep dielectric charging type, which are caused by charge accumulation and subsequent discharge of relativistic electrons. In this study we examine whether there is any energy dependence in relativistic electron enhancements at geosynchronous altitudes during solar energetic proton events of 2005.  相似文献   

Dynamic groundwater resources of National Capital Territory,Delhi: assessment,development and management options   总被引：4，自引：2，他引：2  

Rana Chatterjee  B. K. Gupta  S. K. Mohiddin  P. N. Singh  Shashank Shekhar  Rajaram Purohit 《Environmental Earth Sciences》2009,59(3):669-686

Groundwater is one of the important source of water supply to meet the requirements of National Capital Territory (NCT) of Delhi, India which is a fast developing urban conglomeration. An assessment of dynamic groundwater resources of NCT Delhi has been attempted based on the methodology known as Ground Water Resources Estimation Methodology—1997. The methodology includes assessment of annual replenishable groundwater resources using water level fluctuation approach and empirical norms, estimation of the annual quantity of groundwater withdrawal and categorization of the assessment units based on the status of groundwater utilization and water level trend. Annual replenishable groundwater resources of NCT Delhi is about 297 million cubic meter (mcm) while the annual groundwater draft is about 480 mcm. This is because of over-exploitation of replenishable resources in seven out of nine districts of the Capital Territory. Based on the assessment of dynamic groundwater resources, a broad groundwater management plan has been proposed in this paper. This include augmentation of groundwater resources through rain water harvesting schemes to be implemented on a large scale, regulation on groundwater withdrawal in vulnerable areas, development of Yamuna flood plain aquifer and declaration of Delhi ridge as groundwater sanctuary.  相似文献   

Effect of the presence of a conducting channel between India and Sri Lanka Island on the features of the equatorial electrojet     

Mita Rajaram  B. P. Singh  N. Nityananda  A. K. Agrawal 《Geophysical Journal International》1979,56(1):127-138

Summary. Transient geomagnetic variations like SSCs, Bays, Sq and storm-time variations show anomalously large Z amplitudes at the three permanent magnetic observatories in India under the equatorial electrojet. Our earlier studies have shown that these anomalies cannot be explained in terms of the usual coastal effect. Another unique feature of this area is the small equatorial enhancement of all magnetic fluctuations, which still remains to be completely understood. It is also noticed that Z/H ratio at Annamalainagar is very large for night-time variations but becomes insignificant for day-time fluctuations, whereas no such large difference is seen at Trivandrum, the other coastal station. All the above features have been explained here by introducing the presence of a conducting channel in the lower crust or upper mantle between India and Sri Lanka Island. The anomalies of the equatorial electrojet in the Indian region thus do not necessitate the conducting surface of the mantle to be deeper in this area as has been suggested by earlier workers. A less conducting mantle in the Indian region otherwise could be difficult to incorporate in the present theories of mantle convection when this area is known to be tectonically active. The presence of the conducting channel is further confirmed by analogue model experiments of Papamastorakis. We further observe that the equatorial electrojet does have an associated internal part in the Indian region.  相似文献   

An explanation of induced magnetic variations at Sabhawala,India     

N. Nityananda  A.K. Agarwal  B.P. Singh 《Physics of the Earth and Planetary Interiors》1981,25(3):226-231

Induction vectors calculated for short-period events such as “bays” and “storm sudden commencements” (SSCs) indicate that the conductor causing the anomaly lies to the south of Sabhawala. The nature of vertical transfer functions obtained from spectral analysis of storm-time variations further confirms the presence of such a conductor. The nature of maximum (G_p) and minimum (G₁) response functions suggests that a two-dimensional conductor south of Sabhawala is responsible for anomalies in Z. Invoking a structural model of the Earth's crust beneath the Himalayas, in keeping with accepted orogenic theories, we propose that one structure capable of producing the desired conducting path is a rise of the asthenosphere south of the Himalayan range. Another important factor contributing to the induced variations at Sabhawala is due to a sedimentary trough running parallel to the Himalayas, again to the south. These views are confirmed by a two-dimensional model calculation. It is found that the undulation of the asthenosphere alone does not reproduce the nature of the anomalies in H and Z.  相似文献   

Induction at short periods in the horizontal field variations in the Indian peninsula     

N. Nityananda  A.K. Agarwal  B.P. Singh 《Physics of the Earth and Planetary Interiors》1977,15(1):P5-P9

A study of the horizontal components of certain short-period magnetic-fluctuation events, viz., storm sudden commencements and bays, shows appreciable anomalies at two of the five magnetic observatories in peninsular India. The electric current patterns deduced from the magnetic horizontal induced variations imply channelling of induced currents through the Palk Straits and around the southern tip of the Indian peninsula. An interesting feature of these anomalies is that while the induced magnetic vertical variations are strongly correlated with the horizontal northward magnetic field, the electric current concentrations flow parallel to the coast; southwest, near Annamalainagar, and north near Trivandrum. The observations are interpreted in terms of a regional, east-west, induced electric current pattern which is perturbed in the vicinity of the two observatories by the Indian peninsula.  相似文献   

Application of ridge-regression in inversion of low-latitude magnetic anomalies derived from space measurements     

V.J. Bapat  B.P. Singh  Mita Rajaram 《Earth and Planetary Science Letters》1987,84(2-3)

Anomalies in total field, horizontal, and vertical components over the Indian region derived from MAGSAT measurements have been inverted through the ridge-regression method, basically to test: (1) the application of the method in deriving a stable estimate of crustal magnetisation, and (2) the relative amount of information on crustal magnetisation contained in scalar vis-a`-vis vector data. Results show that the instabilities in magnetisation solution that appear when Mayhew's conventional method is applied in low latitudes could be removed through the ridge-regression technique. It was also noticed that magnetisation distribution estimated through the inversion of the total field(B) does not relate well with the geological features in the equatorial region. Inversion of theZ-anomaly alone gives realistic results for the equatorial region but not over higher latitudes. We conclude that a joint inversion ofX- andZ-anomalies provides a magnetisation estimate consistent with known geological features both for equatorial and higher latitudes.  相似文献