Earthquakes are one among the highly dangerous geological hazards. The damage from earthquakes is greatly influenced by the local geological conditions. The history of Pakistan is full of severe earthquakes that caused the mass destruction at national scale. Major earthquake-affected areas in Pakistan are mainly concentrated in the north and western sections of the country. Site response analysis is an initial step towards seismic risk assessment. The present study aims at local site effects by acquiring data along 105 sites of Rawalpindi-Islamabad, the twin cities of federal capital of Pakistan, by applying H/V spectral ratio method. Out of the data acquired for 105 sites, data for 88 sites were considered reliable after observing reliability conditions determined by SESAME guidelines devised in 2004. Fundamental frequency f 0 of soft sediments, amplitude A 0 of corresponding H/V spectral ratios, thickness of soft sediments residing on the bedrock and soil vulnerability index K g over 88 reliable data sites within the study area were estimated and analysed. The results show that the fundamental frequency of the sediments reflects variation and lies within a wide range between 0.6 and 14.4 Hz. Similarly, amplification factor A 0 up to 5.5 was observed at a site. Overburden thickness of soft sediments H also indicates high variation and has been calculated in the range of 1.7-316.5 m. As far as K g is concerned, it is also highly variable and is lying in the range of 0.30-62.7. These results will help in designing a policy to mitigate the impact of seismic hazard in the study area.

Local geology or local site effect is a crucial component while conducting seismic risk assessment studies. Investigations made by utilization of ambient noise are an effective tool for local site estimation. The present study is conducted to perform site response analysis at 13 different sites within urban settlements of Fateh jang area (Pakistan). The aim of this study was achieved by utilizing Nakamura method or H/V spectral ratio method. Some important local site parameters, e.g., the fundamental frequencies f 0 of soft sediments, amplitudes A 0 of corresponding H/V spectral ratios, and alluvium thicknesses over 13 sites within the study area, were measured and analyzed. The results show that the study area reflects low fundamental frequency f 0 . The fundamental frequencies of the sediments are highly variable and lie in a range of 0.6-13.0 Hz. Similarly, amplification factors at these sites are in the range of 2.0-4.0.

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