The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Dipok K. Bora - One of the best experts on this subject based on the ideXlab platform.
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Scaling relations of moment magnitude, local magnitude, and duration magnitude for earthquakes originated in northeast India
Earthquake Science, 2016Co-Authors: Dipok K. BoraAbstract:In this study, we aim to improve the scaling between the moment magnitude ( M _W), local magnitude ( M _L), and the duration magnitude ( M _D) for 162 earthquakes in Shillong-Mikir plateau and its Adjoining Region of northeast India by extending the M _W estimates to lower magnitude earthquakes using spectral analysis of P-waves from vertical component seismograms. The M _W- M _L and M _W- M _D relationships are determined by linear regression analysis. It is found that, M _W values can be considered consistent with M _L and M _D, within 0.1 and 0.2 magnitude units respectively, in 90 % of the cases. The scaling relationships investigated comply well with similar relationships in other Regions in the world and in other seismogenic areas in the northeast India Region.
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Estimation of Source Parameters of Local Earthquakes Originated in Shillong-Mikir Plateau and its Adjoining Region of Northeastern India
Bulletin of the Seismological Society of America, 2013Co-Authors: Dipok K. Bora, Saurabh Baruah, Rajib Biswas, N. GogoiAbstract:Abstract We estimate the source parameters (seismic moment, source radius, stress drop, and source displacement) and scaling laws for local earthquakes that occurred in the Shillong–Mikir plateau, Assam Valley, and Arunachal Himalaya in northeast India during 2001–2008. The source parameters were determined using the spectral analysis of P waves from the vertical component seismograms, after correction for attenuation. Seismic moments are observed within the range from 9.51×10 12 to ; stress drop ranges from 4×10 5 to 9×10 7 Pa for the Brune model and 7×10 5 to 1×10 8 Pa for the Madariaga model. Seismic events in this study are prominent with an average stress drop of 0.1–10 MPa. The effect of site geology may be a contributing factor for such a variation in stress drop. Source dimensions are, however, found to be smaller within the major part of the plateau. It is suggested that local earthquakes in the Region are associated with a brittle shear‐failure mechanism on fault segments and/or the presence of weakened zones, and earthquakes are triggered by low deviatoric stress. Empirical relations between M w – M L and M 0 – M L are developed leading to the future prediction of calibration coefficients for the local earthquakes in the Shillong–Mikir plateau and its Adjoining Region. Online Material: Tables of source parameters.
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mapping the crustal thickness in shillong mikir hills plateau and its Adjoining Region of northeastern india using moho reflected waves
Journal of Asian Earth Sciences, 2012Co-Authors: Dipok K. Bora, Saurabh BaruahAbstract:Abstract In this study we have tried to detect and collect later phases associated with Moho discontinuity and used them to study the lateral variations of the crustal thickness in Shillong–Mikir Hills Plateau and its Adjoining Region of northeastern India. We use the inversion algorithm by Nakajima et al. (Nakajima, J., Matsuzawa, T., Hasegawa, A. 2002. Moho depth variation in the central part of northeastern Japan estimated from reflected and converted waves. Physics of the Earth and Planetary Interiors, 130, 31–47), having epicentral distance ranging from 60 km to 150 km. Taking the advantage of high quality broadband data now available in northeast India, we have detected 1607 Moho reflected phases (PmP and SmS) from 300 numbers of shallow earthquake events (depth ⩽ 25 km) in Shillong–Mikir Hills Plateau and its Adjoining Region. Notably for PmP phase, this could be identified within 0.5–2.3 s after the first P-arrival. In case of SmS phase, the arrival times are observed within 1.0–4.2 s after the first S-arrival. We estimated the crustal thickness in the study area using travel time difference between the later phases (PmP and SmS) and the first P and S arrivals. The results shows that the Moho is thinner beneath the Shillong Plateau about 35–38 km and is the deepest beneath the Brahmaputra valley to the north about 39–41 km, deeper by 4–5 km compared to the Shillong Plateau with simultaneous observation of thinnest crust (∼33 km) in the western part of the Shillong Plateau in the Garo Hills Region.
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Mapping the crustal thickness in Shillong–Mikir Hills Plateau and its Adjoining Region of northeastern India using Moho reflected waves
Journal of Asian Earth Sciences, 2012Co-Authors: Dipok K. Bora, Saurabh BaruahAbstract:Abstract In this study we have tried to detect and collect later phases associated with Moho discontinuity and used them to study the lateral variations of the crustal thickness in Shillong–Mikir Hills Plateau and its Adjoining Region of northeastern India. We use the inversion algorithm by Nakajima et al. (Nakajima, J., Matsuzawa, T., Hasegawa, A. 2002. Moho depth variation in the central part of northeastern Japan estimated from reflected and converted waves. Physics of the Earth and Planetary Interiors, 130, 31–47), having epicentral distance ranging from 60 km to 150 km. Taking the advantage of high quality broadband data now available in northeast India, we have detected 1607 Moho reflected phases (PmP and SmS) from 300 numbers of shallow earthquake events (depth ⩽ 25 km) in Shillong–Mikir Hills Plateau and its Adjoining Region. Notably for PmP phase, this could be identified within 0.5–2.3 s after the first P-arrival. In case of SmS phase, the arrival times are observed within 1.0–4.2 s after the first S-arrival. We estimated the crustal thickness in the study area using travel time difference between the later phases (PmP and SmS) and the first P and S arrivals. The results shows that the Moho is thinner beneath the Shillong Plateau about 35–38 km and is the deepest beneath the Brahmaputra valley to the north about 39–41 km, deeper by 4–5 km compared to the Shillong Plateau with simultaneous observation of thinnest crust (∼33 km) in the western part of the Shillong Plateau in the Garo Hills Region.
Saurabh Baruah - One of the best experts on this subject based on the ideXlab platform.
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Estimation of Source Parameters of Local Earthquakes Originated in Shillong-Mikir Plateau and its Adjoining Region of Northeastern India
Bulletin of the Seismological Society of America, 2013Co-Authors: Dipok K. Bora, Saurabh Baruah, Rajib Biswas, N. GogoiAbstract:Abstract We estimate the source parameters (seismic moment, source radius, stress drop, and source displacement) and scaling laws for local earthquakes that occurred in the Shillong–Mikir plateau, Assam Valley, and Arunachal Himalaya in northeast India during 2001–2008. The source parameters were determined using the spectral analysis of P waves from the vertical component seismograms, after correction for attenuation. Seismic moments are observed within the range from 9.51×10 12 to ; stress drop ranges from 4×10 5 to 9×10 7 Pa for the Brune model and 7×10 5 to 1×10 8 Pa for the Madariaga model. Seismic events in this study are prominent with an average stress drop of 0.1–10 MPa. The effect of site geology may be a contributing factor for such a variation in stress drop. Source dimensions are, however, found to be smaller within the major part of the plateau. It is suggested that local earthquakes in the Region are associated with a brittle shear‐failure mechanism on fault segments and/or the presence of weakened zones, and earthquakes are triggered by low deviatoric stress. Empirical relations between M w – M L and M 0 – M L are developed leading to the future prediction of calibration coefficients for the local earthquakes in the Shillong–Mikir plateau and its Adjoining Region. Online Material: Tables of source parameters.
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mapping the crustal thickness in shillong mikir hills plateau and its Adjoining Region of northeastern india using moho reflected waves
Journal of Asian Earth Sciences, 2012Co-Authors: Dipok K. Bora, Saurabh BaruahAbstract:Abstract In this study we have tried to detect and collect later phases associated with Moho discontinuity and used them to study the lateral variations of the crustal thickness in Shillong–Mikir Hills Plateau and its Adjoining Region of northeastern India. We use the inversion algorithm by Nakajima et al. (Nakajima, J., Matsuzawa, T., Hasegawa, A. 2002. Moho depth variation in the central part of northeastern Japan estimated from reflected and converted waves. Physics of the Earth and Planetary Interiors, 130, 31–47), having epicentral distance ranging from 60 km to 150 km. Taking the advantage of high quality broadband data now available in northeast India, we have detected 1607 Moho reflected phases (PmP and SmS) from 300 numbers of shallow earthquake events (depth ⩽ 25 km) in Shillong–Mikir Hills Plateau and its Adjoining Region. Notably for PmP phase, this could be identified within 0.5–2.3 s after the first P-arrival. In case of SmS phase, the arrival times are observed within 1.0–4.2 s after the first S-arrival. We estimated the crustal thickness in the study area using travel time difference between the later phases (PmP and SmS) and the first P and S arrivals. The results shows that the Moho is thinner beneath the Shillong Plateau about 35–38 km and is the deepest beneath the Brahmaputra valley to the north about 39–41 km, deeper by 4–5 km compared to the Shillong Plateau with simultaneous observation of thinnest crust (∼33 km) in the western part of the Shillong Plateau in the Garo Hills Region.
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Mapping the crustal thickness in Shillong–Mikir Hills Plateau and its Adjoining Region of northeastern India using Moho reflected waves
Journal of Asian Earth Sciences, 2012Co-Authors: Dipok K. Bora, Saurabh BaruahAbstract:Abstract In this study we have tried to detect and collect later phases associated with Moho discontinuity and used them to study the lateral variations of the crustal thickness in Shillong–Mikir Hills Plateau and its Adjoining Region of northeastern India. We use the inversion algorithm by Nakajima et al. (Nakajima, J., Matsuzawa, T., Hasegawa, A. 2002. Moho depth variation in the central part of northeastern Japan estimated from reflected and converted waves. Physics of the Earth and Planetary Interiors, 130, 31–47), having epicentral distance ranging from 60 km to 150 km. Taking the advantage of high quality broadband data now available in northeast India, we have detected 1607 Moho reflected phases (PmP and SmS) from 300 numbers of shallow earthquake events (depth ⩽ 25 km) in Shillong–Mikir Hills Plateau and its Adjoining Region. Notably for PmP phase, this could be identified within 0.5–2.3 s after the first P-arrival. In case of SmS phase, the arrival times are observed within 1.0–4.2 s after the first S-arrival. We estimated the crustal thickness in the study area using travel time difference between the later phases (PmP and SmS) and the first P and S arrivals. The results shows that the Moho is thinner beneath the Shillong Plateau about 35–38 km and is the deepest beneath the Brahmaputra valley to the north about 39–41 km, deeper by 4–5 km compared to the Shillong Plateau with simultaneous observation of thinnest crust (∼33 km) in the western part of the Shillong Plateau in the Garo Hills Region.
Thomas H. Painter - One of the best experts on this subject based on the ideXlab platform.
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episodic dust events of utah s wasatch front and Adjoining Region
Journal of Applied Meteorology and Climatology, 2012Co-Authors: James W Steenburgh, Jeffrey D. Massey, Thomas H. PainterAbstract:AbstractEpisodic dust events cause hazardous air quality along Utah’s Wasatch Front and dust loading of the snowpack in the adjacent Wasatch Mountains. This paper presents a climatology of episodic dust events of the Wasatch Front and Adjoining Region that is based on surface weather observations from the Salt Lake City International Airport (KSLC), Geostationary Operational Environmental Satellite (GOES) imagery, and additional meteorological datasets. Dust events at KSLC—defined as any day [mountain standard time (MST)] with at least one report of a dust storm, blowing dust, and/or dust in suspension with a visibility of 10 km or less—average 4.3 per water year (WY: October–September), with considerable interannual variability and a general decline in frequency during the 1930–2010 observational record. The distributions of monthly dust-event frequency and total dust flux are bimodal, with primary and secondary maxima in April and September, respectively. Dust reports are most common in the late afterno...
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Episodic Dust Events of Utah’s Wasatch Front and Adjoining Region
Journal of Applied Meteorology and Climatology, 2012Co-Authors: W. James Steenburgh, Jeffrey D. Massey, Thomas H. PainterAbstract:AbstractEpisodic dust events cause hazardous air quality along Utah’s Wasatch Front and dust loading of the snowpack in the adjacent Wasatch Mountains. This paper presents a climatology of episodic dust events of the Wasatch Front and Adjoining Region that is based on surface weather observations from the Salt Lake City International Airport (KSLC), Geostationary Operational Environmental Satellite (GOES) imagery, and additional meteorological datasets. Dust events at KSLC—defined as any day [mountain standard time (MST)] with at least one report of a dust storm, blowing dust, and/or dust in suspension with a visibility of 10 km or less—average 4.3 per water year (WY: October–September), with considerable interannual variability and a general decline in frequency during the 1930–2010 observational record. The distributions of monthly dust-event frequency and total dust flux are bimodal, with primary and secondary maxima in April and September, respectively. Dust reports are most common in the late afterno...
B P Kashyap - One of the best experts on this subject based on the ideXlab platform.
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Effect of processing on properties of thin walled calandria tubes for pressurised heavy water reactor
Journal of Nuclear Materials, 2003Co-Authors: K. Kapoor, T Sanyal, C. Padmaprabu, B P KashyapAbstract:Thin walled calandria tubes for pressurised heavy water reactors are manufactured either by seam welding of Zircaloy-4 sheets or by seamless route. In the present study, the effect of processing on the critical properties such as texture, microstructure, hydriding behaviour and residual stress for both the routes as well as the mechanical anisotropy developed due to seam welding are investigated. The properties of the seam welded tube in the fusion and Adjoining Region are markedly different from the base material and from the seamless tube. Residual stress measurements indicate that heat affected zone (HAZ) of seam welded tubes have longitudinal tensile residual stress and the seamless tubes have uniform compressive stress along the circumference. The phase transition in the presence of residual stresses due to thermal gradient is found to modify the texture in the HAZ. The hydride orientation and mechanical anisotropy in these Regions are found to be dependent on the texture of the material.
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Effect of processing on properties of thin walled calandria tubes for pressurised heavy water reactor
Journal of Nuclear Materials, 2003Co-Authors: K. Kapoor, T Sanyal, C. Padmaprabu, S.v Ramana Rao, B P KashyapAbstract:Thin walled calandria tubes for pressurised heavy water reactors are manufactured either by seam welding of Zircaloy-4 sheets or by seamless route. In the present study, the effect of processing on the critical properties such as texture, microstructure, hydriding behaviour and residual stress for both the routes as well as the mechanical anisotropy developed due to seam welding are investigated. The properties of the seam welded tube in the fusion and Adjoining Region are markedly different from the base material and from the seamless tube. Residual stress measurements indicate that heat affected zone (HAZ) of seam welded tubes have longitudinal tensile residual stress and the seamless tubes have uniform compressive stress along the circumference. The phase transition in the presence of residual stresses due to thermal gradient is found to modify the texture in the HAZ. The hydride orientation and mechanical anisotropy in these Regions are found to be dependent on the texture of the material.© Elsevie
N. Gogoi - One of the best experts on this subject based on the ideXlab platform.
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Estimation of Source Parameters of Local Earthquakes Originated in Shillong-Mikir Plateau and its Adjoining Region of Northeastern India
Bulletin of the Seismological Society of America, 2013Co-Authors: Dipok K. Bora, Saurabh Baruah, Rajib Biswas, N. GogoiAbstract:Abstract We estimate the source parameters (seismic moment, source radius, stress drop, and source displacement) and scaling laws for local earthquakes that occurred in the Shillong–Mikir plateau, Assam Valley, and Arunachal Himalaya in northeast India during 2001–2008. The source parameters were determined using the spectral analysis of P waves from the vertical component seismograms, after correction for attenuation. Seismic moments are observed within the range from 9.51×10 12 to ; stress drop ranges from 4×10 5 to 9×10 7 Pa for the Brune model and 7×10 5 to 1×10 8 Pa for the Madariaga model. Seismic events in this study are prominent with an average stress drop of 0.1–10 MPa. The effect of site geology may be a contributing factor for such a variation in stress drop. Source dimensions are, however, found to be smaller within the major part of the plateau. It is suggested that local earthquakes in the Region are associated with a brittle shear‐failure mechanism on fault segments and/or the presence of weakened zones, and earthquakes are triggered by low deviatoric stress. Empirical relations between M w – M L and M 0 – M L are developed leading to the future prediction of calibration coefficients for the local earthquakes in the Shillong–Mikir plateau and its Adjoining Region. Online Material: Tables of source parameters.
