Evaluation of seismic hazard of Uttarakhand State of India through deterministic approach.

Uttarakhand is one of the most seismically active states of India. In this study, the seismic hazard map of Uttarakhand has been developed through deterministic seismic hazard analysis approach. Seismotectonic map with various geological discontinuities has been prepared. A homogenous earthquake catalogue for moment magnitude has been prepared for the duration of 1953–2020 and the past seismic data have been checked for completeness with regard to time and magnitude. Maximum potential magnitude was then assessed for the seismic sources. Concept of logic tree with four different ground motion prediction models was employed for the assessment of hazards. For developing the microzonation map, the state was divided into several grid points (0.1°×0.1°), and the seismic hazard was estimated in terms of peak ground acceleration (PGA) for each of the grid points. The estimated PGA values were found to be varying from 0.12 g to as high as 0.70 g. For northern regions, Main Central Thrust, Sundernagar and Ropar faults are critical, whereas for southern regions, thrusts TT18, TT23, TT19, TT23 and faults F37, F36, and F31 are significant. It has also been observed that the current Indian standard underestimates the response spectrum values for most regions of the state. [ABSTRACT FROM AUTHOR]