Post-2004 mega-earthquake temporal velocity variation at Andaman Islands from GPS measurements   总被引：1，自引：1，他引：0  

S. K. Som  Ashim Kumar Saha  Vijay Shivgotra 《Natural Hazards》2014,72(2):1051-1062

Post-mega-earthquake velocity adjustment at Andaman region was found to vary with time. Coordinate repeatability for 5-year span shows changeover from post-seismic to inter-seismic period in between 900 and 1,000 days from the mega-earthquake. Excluding Havlock Island, all sites move from south to north and from east to west. Velocity vectors gradually rotated from the nearly perpendicular orientation after the mega-earthquake to parallel orientation with the subduction interface in later phase. Velocities in India 2005 reference frame indicate the presence of a structural discontinuity between Bedonabad and Chidiatapu at south Andaman, between Padmanavapuram and Kaushalyanagar at middle Andaman and between Aerial Bay and Radhanagar at north Andaman.  相似文献   

Bianchi type VI cosmological models: a Scale-Covariant study     

Mohammad Zeyauddin  Bijan Saha 《Astrophysics and Space Science》2013,343(1):445-450

A model for an anisotropic Bianchi type VI universe in a Scale Covariant theory of gravitation (Canuto et al. in Phys. Rev. D 16:6, 1977a; Phys. Rev. Lett. 39:8, 1977b) is analyzed. Exact solutions to the corresponding field equations are found under some specific assumptions. A finite singularity is found in the model at the initial time t=0. All the physical parameters are studied and thoroughly discussed. The model behaves like a big bang singular model o f the universe.  相似文献   

Evaluation of hydrogeochemical processes in arsenic-contaminated alluvial aquifers in parts of Mid-Ganga Basin,Bihar, Eastern India   总被引：1，自引：1，他引：0  

Dipankar Saha  Sreehari S. Sarangam  Shailendra N. Dwivedi  Kuldeep G. Bhartariya 《Environmental Earth Sciences》2010,61(4):799-811

The study region covers 1,650 km² of the Mid-Ganga Basin in Bihar, experiencing intensive groundwater draft. The area forms a part of the Gangetic alluvial plain where high incidence of arsenic groundwater contamination (>50 μg/l) has recently been detected. Seventy-seven groundwater samples have been collected and analysed for major ions, iron and arsenic. Arsenic contamination (max 620 μg/l) is confined in hand pump zones (15–35 m) within the newer alluvium deposited during Middle Holocene to Recent age. The older alluvial aquifers are arsenic-safe and recorded maximum concentration as 9 μg/l. Out of 12 hydrochemical facies identified, four have been found arsenic-affected: Ca–HCO₃, Mg–HCO₃, Ca–Mg–HCO₃ and Mg–Ca–HCO₃. The geochemical evolution of groundwater, as investigated by graphical interpretation and statistical techniques (correlation, principal component analysis) revealed that dissolution of detrital calcite, dolomite and infiltration of rainwater are the major processes shaping the groundwater chemistry in the newer alluvium. Arsenic and iron showed strong positive correlation. Rainfall infiltration, carrying organic matter from recently accumulated biomass from this flood-prone belt, plays a critical role in releasing arsenic and iron present in the sediments. Geochemical evolution of groundwater in older alluvium follows a different path, where cation-exchange has been identified as a significant process.  相似文献