Ground-motion predictions in Shillong region, northeast India   总被引：1，自引：0，他引：1  

Sankar Kumar Nath  Kiran Kumar Singh Thingbaijam  Soumya Kanti Maiti  Avinash Nayak 《Journal of Seismology》2012,16(3):475-488

We deliver ground-motion prediction equations for Shillong region, northeast India, based on a database generated by finite-fault stochastic simulations. An examination of the regional seismic source characteristics is carried out beforehand. Micro/minor earthquakes (M _W?<?5.0) nucleating at hypocentral depth <21?km in the region recorded at broadband seismic stations are observed to have Brune stress-drop ranging between 2.8 and 99.9?bars. Likewise, macroseismic intensity data for the 1897 Shillong Earthquake that nucleated at a hypocentral depth of ~35?km places the associated stress-drop at 100?200?bars. The apparent variation of the stress-drop parameter with depth is considered with two source zones namely lower-crust and upper-crust. Equations for the lower-crust predict higher ground-motion levels and exhibit affinity to those developed for stable continental region of Eastern North America. The ground-motion levels predicted by the equations for the upper-crust are relatively lower but are still higher compared with those predicted for tectonically active regions, viz., the Himalayas and Western North America.  相似文献   

Estimation of attenuation characteristics of Aswan reservoir region,Egypt     

S. Mukhopadhyay  Birinder Singh  H. Mohamed 《Journal of Seismology》2016,20(1):79-92

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Bioinoculants and Vermicompost Improve Ocimum basilicum Yield and Soil Health in a Sustainable Production System          下载免费PDF全文

Sanjeet K. Verma  Umesh Pankaj  Khushboo Khan  Rakshapal Singh  Rajesh Kumar Verma 《洁净——土壤、空气、水》2016,44(6):686-693

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Understanding the Development of Environmental Resistance Among Microbes: A Review          下载免费PDF全文

Jatin Srivastava  Harish Chandra  Nandita Singh  Swinder J. S. Kalra 《洁净——土壤、空气、水》2016,44(7):901-908

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Displacement-based seismic design of flat slab-shear wall buildings     

Subhajit Sen  Yogendra Singh 《地震工程与工程振动(英文版)》2016,15(2):209-221

Flat slab system is becoming widely popular for multistory buildings due to its several advantages. However, the performance of flat slab buildings under earthquake loading is unsatisfactory due to their vulnerability to punching shear failure. Several national design codes provide guidelines for designing flat slab system under gravity load only. Nevertheless, flat slab buildings are also being constructed in high seismicity regions. In this paper, performance of flat slab buildings of various heights, designed for gravity load alone according to code, is evaluated under earthquake loading as per ASCE/SEI 41 methodology. Continuity of slab bottom reinforcement through column cage improves the performance of flat slab buildings to some extent, but it is observed that these flat slab systems are not adequate in high seismicity areas and need additional primary lateral load resisting systems such as shear walls. A displacement-based method is proposed to proportion shear walls as primary lateral load resisting elements to ensure satisfactory performance. The methodology is validated using design examples of flat slab buildings with various heights.  相似文献   

Anomalous Variations of Ionosphere Associated with the Strong Earthquake at Pakistan-Iran Border at a Low Latitude Station Agra,India     

Devbrat Pundhir  Birbal Singh  O. P. Singh  Saral K. Gupta 《Acta Geophysica》2016,64(3):796-809

In this paper, we analyze the TEC data for April 2013 observed at Agra station, India (geogr. lat. 27.2° N, long. 78° E) to examine the effect of earthquake of magnitude M = 7.8 which occurred on 16 April 2013 at Pakistan–Iran border region. We process the TEC data using the s statistical criterion to find out anomalous variation in TEC data. We also study the VLF propagation signal from NPM, Hawaii (21.42° N, 158° W), which is monitored at the same station (Agra station) in the light of this earthquake as well as solar flares. The nighttime fluctuation method is used to analyze the VLF data for the period of ±5 days from the day of earthquake (11–21 April 2013). The anomalous enhancements and depletions are found in TEC data on 1–9 days before the occurrence of event.  相似文献   

A Study of Early/Slow VLF Perturbations Observed at Agra,India     

Uma Pandey  Ashutosh K. Singh  Om P. Singh  Birbal Singh  Vibhav K. Saraswat 《Acta Geophysica》2016,64(3):755-771

We present here the results of sub-ionospheric VLF perturbations observed on NWC (19.8 kHz) transmitter signal propagating in the Earth-ionosphere waveguide, monitored at our low latitude station Agra. During the period of observation (June-December 2011), we found 89 cases of VLF perturbation, while only 73 cases showing early character associated with strong lightning discharges. Out of 73 events, 64 (~84%) of the early VLF perturbations are found to be early/slow in nature; the remaining 9 events are early/fast. The onset duration of these early/slow VLF perturbations is up to ~ 5 s. A total of 54 observed early events show amplitude change lying between ± 3.0 dB, and phase change ± 12 degree, respectively, and found to occur mainly during nighttime. One of the interesting results we found is that the events with larger recovery time lie far away from the VLF propagation path, while events with smaller duration of recovery are within the ± 50–100 km of signal path. The World Wide Lightning Location Network (WWLLN) data is analysed to find the location of causative lightning and temporal variation. The lightning discharge and associated processes that lead to early VLF events are discussed.  相似文献   

Effect of Corrugation and Reinforcement on the Dispersion of SH-wave Propagation in Corrugated Poroelastic Layer Lying over a Fibre-reinforced Half-space   总被引：1，自引：1，他引：0  

Abhishek Kumar Singh  Amrita Das  Anirban Lakshman  Amares Chattopadhyay 《Acta Geophysica》2016,64(5):1340-1369

The presence of porosity and reinforcement in a medium is an important factor affecting seismic wave propagation and plays vital role in many geophysical prospects. Also, the presence of salt and ore deposits, mountains, basins, mountain roots, etc. is responsible for the existence of corrugated boundary surfaces of constituent layers. Such facts brought motivation for the present paper which deals with the propagation of SH-wave in a heterogeneous fluid-saturated poroelastic layer with corrugated boundaries lying over an initially stressed fibre-reinforced elastic halfspace. Closed form of dispersion relation has been obtained and is found in well agreement to classical Love wave equation for isotropic case. The effect of corrugation, wave number, undulation, position parameter, horizontal compressive/tensile initial stress and heterogeneity on phase velocity has been analysed through numerical computation and graphical illustration. Moreover, comparative study exploring the effect of presence and absence of reinforcement in half-space on dispersion curve is the major highlight of the current study.  相似文献   

Lithosphere of the Dharwar craton by joint inversion of P and S receiver functions   总被引：1，自引：0，他引：1  

S. Kiselev  L. Vinnik  S. Oreshin  S. Gupta  S. S. Rai  A. Singh  M. R. Kumar  G. Mohan 《Geophysical Journal International》2008,173(3):1106-1118

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Evolution of primordial black holes in Jordan–Brans–Dicke cosmology     

A. S. Majumdar  D. Gangopadhyay  L. P. Singh 《Monthly notices of the Royal Astronomical Society》2008,385(3):1467-1470

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