Soil characteristics and site effect assessment in the city of Delhi (India) using H/V and f–k methods

Abstract

Local site conditions substantially affect the characteristics of seismic waves and its potential to cause earthquake damage. To accurately identify the variation of seismic hazard at different locations within the cities, measurements from a three-component station may be used for estimating the resonance frequencies and evaluate the expected level of damage at each site. This information can also be complemented with array measurements of ambient noise in order to estimate the V s profiles and characterize the corresponding sediment layers at each site. In this work, ambient noise measurements were taken at 116 sites around the city of Delhi, India, and the fundamental resonance frequencies were estimated through the H/V technique. At the same time, array measurements were also taken at three different areas of the city, where it is expected that the mean soil thickness may differ. The f–k technique was applied for obtaining the dispersion curves and the neighborhood algorithm was used for estimating the S-wave velocity profiles at each area. Combining the information provided for both methods, we characterized the soil sediments of the city of Delhi, obtaining different zones of resonance frequency, soil thickness and mean S-wave velocity. Moreover, an estimation of the best suitable S-wave velocity profiles is proposed.