[S07-3] Hazard and risk assessment II

[S07-3-04] ANALYSIS OF RESPONSE SPECTRA OF CHARACTERISTIC GROUND MOTIONS RECORDED IN NORTH EAST INDIAN REGION

^○Babita Sharma^{1, 2} (1.Presently JICA Trainee (Seismology) from October 2016 to September 2017 at IISEE, Tsukuba, Japan, 2.Parent Organization National Centre for Seismology, Ministry of Earth Sciences, New Delhi, India)

The response spectra are influenced by the local site conditions and regional geology. For various categories of rock sites like hard rocks (Proterozoic period), sedimentary rocks (Tertiary period) and alluvium (Quaternary period) exhibit this effect for North East (NE) Indian region. This has been analyzed using 195 strong ground motion histories from 45 earthquakes occurred in NE India having the magnitude range of Mw 3.5 to 6.9 recorded from 2008 to 2014 on strong motion network of India. The ground motion is amplified at higher frequencies for stations located on hard rock while for stations located on alluvium sites are amplified comparatively at lower frequencies. Also the sites located on hard rock show lower spectral acceleration than alluvium sites. The acceleration response spectra in the current Indian code designed for the entire country is applicable for all rock types for the study area. The effects of important ground motion parameters like magnitude, distance, local geology and site conditions on acceleration response spectra are studied. The response analysis constitutes the importance in representing the seismic hazard assessment of an area especially for NE Indian region as this falls in the zone V on the seismic zonation map of India. This study is important for the seismic hazard assessment of the NE India which is an active plate boundary having complex seismotectonics.