Comparative Analysis of SSR and HVSR Method for Site Response Analysis

The Northeast part of India falls under seismic Zone V (IS:1893–2002), the highest seismic activity zone. However, there is a lack of sufficient dense seismic arrays in the region to record the seismic activity. Irrespective of the availability of the seismic records this study attempts to decsribing the two site response analysis methods: Standard Spectral Ratio (SSR) and Horizontal to Vertical Spectral Ratio (HVSR). Three locations in the west Guwahati Region of the state of Assam in Northeast India, namely, Boko-Palashbari, Goalpara and Guwahati Central Region, have been considered for this study in order to analyze available strong motion data and quantify the site response. The quantification is attempted in terms of site amplification. This chapter also provides a comparison between the two methods under study. 5(five) and 15(fifteen) strong-motion recordings of earthquake events have been considered in this study for the SSR and HVSR methods respectively. The strong motion as recorded in Nongstoin has been considered as a reference site station record for the SSR study. This finding of this study compliments the findings of Field and Jacob (Field and Jacob in Bull Seismol Soc Am 85:1127–1143, 1995) that, if the SSR estimates are taken as the most reliable, the HVSR method under-predicts the site response. The results provided by HVSR are less than that of the SSR results by a factor of 2–4.