Simulation of strong ground motion due to great earthquake in the central seismic gap region of Uttarakhand Himalaya

Uttarakhand Himalaya in India lies in the central seismic gap region identified by Khattri and Tyagi (Tectonophysics 96:281–297, 1983). Most of the area in Uttarakhand state has been placed under zone V (the highest seismic zone) and zone IV (second highest seismic zone) of the seismic hazard map published by Bureau of Indian standard, Govt. of India (BIS in Indian standards code of practice for earthquake resistant Design of Structures, Indian Standards Institution, New Delhi, 2002). Some of the thrust/faults in the region manifest evidence of neotectonics and recurrent seismicity (Valdiya and Pant in Indian Nat Sci Acad 112–117, 1986; Valdiya in Geodynamics of NW Himalaya Gondwana Research Group Memoir 1999; Thakur in Curr Sci 86(II):1544–1560, 2004; Paul et al. in Seismotectonic implications of data recorded by DTSN in the Kumaon region of Himalaya 2004). On the basis of strain accumulation, Bilham et al. (Science 293:1442–1444, 2001) suggested a future magnitude of M ≥ 8 in this region. Therefore, a great earthquake along main central thrust in the central seismic gap region has been modeled using semi-empirical technique of Joshi and Mohan (J Seismol 12:35–51, 2008). For modeling great earthquake, the shear wave quality factor Qβ(f)=30f1.45\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ Q_{\beta } \left( f \right) = 30f^{1.45} $$\end{document} (Joshi et al. in J Earthq Technol 47(1):508, 2010) has been used for Pithoragarh region of Kumaon Himalaya. The strong-motion parameters [peak ground acceleration (PGA), spectral acceleration, and normalized spectral acceleration] are computed at five stations (Sobla, Didihat, Munsiari, Dharchula, and Pithoragarh) in Uttarakhand Himalaya. The maximum PGA of the order of “2g” is computed due to scenario great earthquake in the region at Sobla station. Such type of study is quite helpful for seismic-resistant designs of the buildings in earthquake-prone areas and is essentially required in Uttarakhand Himalaya.