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A new region-specific Ground Motion Prediction Equation (GMPE) was developed for the North and Central Himalayas purely based on recorded strong motion data. The GMPE was generated using multiple-regression, considering ground acceleration, magnitude, and hypocentral distance. An updated larger dataset was used in the present study, making the new equation applicable to a larger magnitude range of 4.1 to 7.8 and distance range up to 1560 kms, thus overcoming a major limitation of currently available region-specific GMPEs. The new GMPE was validated and observed to predict ground acceleration more accurately with noticeably less residuals as compared to existing GMPEs. [ABSTRACT FROM AUTHOR]

Recently developed region-specific GMPEs are used for a comprehensive seismic hazard analysis (SHA) of the North and Central Himalayas (NCH) using a probabilistic approach considering two source models. Vulnerable seismic sources in the areas are identified based on the Seismotectonic Atlas (Dasgupta et al. 2000), published by the Geological Survey of India. An up to date, homogenized and declustered earthquake catalogue is compiled from various sources, with earthquake data since 250 BC, to create a new digitized seismotectonic representation of the region. Regional seismic zones having similar seismicity are recognized based on the Gutenberg-Richter (GR) parameters and the region is delineated into 5 seismic zones. The study area is divided into grids of size 0.05° × 0.05° and the hazard in terms of Peak Ground Acceleration (PGA) at the centre of each grid point is estimated and presented as hazard maps for individual seismic sources, maximum of all sources, and average of both sources. From the current study, it could be concluded that the PGA estimated in the regions is comparatively higher than what is reported in the codal provisions for seismic zonation and estimation of design horizontal acceleration for the region. [ABSTRACT FROM AUTHOR]

The present study attempts to assess the seismic hazard parameters (a, b and M c) and their spatial variation in western Himalaya, central Himalaya and Indo-Gangetic plain areas (19–38 ∘ N and 72–91 ∘ E ). The earthquake catalogue is prepared from different available sources, within a region of 500 km surrounding the study area, in moment magnitude scale. The maximum likelihood estimation method is used for spatial variation of seismicity parameters. The study area is disaggregated into small grids of 0.5 ∘ × 0.5 ∘ , and the spatial variation of seismicity parameters is analysed for the complete catalogue period. A significant variation in seismicity parameters is observed while moving from west to east along the Himalayan belt within the study area. Due to significant variations in seismicity parameters, instead of assigning a lumped value of seismic hazard parameter to the entire region, distributed seismic hazard parameter is assigned by dividing the entire area into five zones, of similar level of seismicity. The estimated seismicity parameter a for these zones varies from 4.28 to 6.18, and for b, it varies from 0.80 to 1.03. Using these Gutenberg–Richter parameters a and b, the present study estimated the return periods and probability of different magnitudes of earthquake for each zone. [ABSTRACT FROM AUTHOR]