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Estimation of seismogenic potential through geological studies of faults is an important step in seismic hazard evaluation and mitigation. We investigated the Katrol Hill Fault (KHF), an E-W trending and south dipping high angle reverse fault in the seismically active Kachchh Basin at the western continental margin of India. While several faults in the eastern part of the basin are presently seismically active, the KHF is the only fault in the entire basin that is shown to have produced three Late Quaternary surface faulting events. We illustrate here an integrated geological approach using field mapping, microscopic analysis (petrography and quartz surface textures using SEM) and shallow geophysical surveys using GPR for determining the precise surface trace of the active KHF. We also determined the displacement and slip-rate for each surface faulting event. Based on the Late Quaternary surface faulting parameters deduced, we calculated the moment magnitude (Mw) of the events using well established empirical relationships. These calculations yielded Mw values consistently ≥ 6.5. Our study shows that the KHF is capable of producing high magnitude earthquakes. We infer that these surface faulting events may be of relatively shallow focus as higher magnitude earthquakes in recent times along other faults in the basin, except the 1819 Allahbund earthquake, did not produce surface rupture. We recommend a revision of seismic hazard risk and mitigation strategies of the region as a consequence of our findings. • Surface trace of active KHF is delineated by GPR, petrographic and quartz surface texture studies. • Mw values of three Late Quaternary surface rupturing events along Katrol Hill Fault are evaluated. • Consistent Mw values of ~6.5 suggest surface rupture hazard to engineering structures. [ABSTRACT FROM AUTHOR]

Abstract: A method for total risk analysis of embankment dams under earthquake conditions is discussed and applied to the selected embankment dams, i.e., Chang, Tapar, Rudramata, and Kaswati located in the Kachchh region of Gujarat, India, to obtain the seismic hazard rating of the dam site and the risk rating of the structures. Based on the results of the total risk analysis of the dams, coupled non-linear dynamic numerical analyses of the dam sections are performed using acceleration–time history record of the Bhuj (India) earthquake as well as five other major earthquakes recorded worldwide. The objective of doing so is to perform the numerical analysis of the dams for the range of amplitude, frequency content and time duration of input motions. The deformations calculated from the numerical analyses are also compared with other approaches available in literature, viz, Makdisi and Seed (1978) approach, Jansen''s approach (1990), Swaisgood''s method (1995), Bureau''s method (1997), Singh et al. approach (2007), and Saygili and Rathje approach (2008) and the results are utilized to foresee the stability of dams in future earthquake scenario. [Copyright &y& Elsevier]

Region-specific seismic hazard analysis was carried out for Krishna Raja Sagara Dam site in Karnataka, India. Seismic event data and seismic source data within a 500 km radius were collected. Deterministic seismic hazard analysis was conducted for different methods of earthquake magnitude and location estimation. It was observed that the ground motion estimates vary widely with different methods of M max estimation and that the rupture based method, which calculates M max based on fault dimensions, can give a reliable estimate of the possible maximum magnitude in regions of low to moderate seismicity. Based on this study, the greatest median ground motion at the dam site is estimated as 0.43 g and the ground motion required to be tolerated without catastrophic failure is considered as 0.11 g. In Stable Continental Regions across the world, where earthquake data is scarce, the methodology followed here can be adopted to conduct region-specific seismic hazard analysis. • Seismic Hazard analysis was carried out using different methods of M max estimation. • GMPEs were selected using Log likelihood as an estimator of efficacy • Rupture based seismic hazard analysis carried out for the dam site can be used in regions with scarce seismic data. • Probable future rupture zones were selected based on past seismicity of the region. • PGA for Maximum Credible Earthquake and Maximum Design Earthquake were estimated. [ABSTRACT FROM AUTHOR]