Frequency dependent attenuation of seismic waves for Delhi and surrounding area, India

Abstract

The attenuation properties of Delhi and surrounding region have been investigated using 62 local earthquakes recorded at nine stations. The frequency dependent quality factors Q α (using P-waves) and Q β (using Swaves) have been determined using the coda normalization method. Quality factor of coda-waves (Qc) has been estimated using the single backscattering model in the frequency range from 1.5 Hz to 9 Hz. Wennerberg formulation has been used to estimate Q i (intrinsic attenuation parameter) and Q s (scattering attenuation parameter) for the region. The values Q α, Q β, Q c, Q i and Q s estimated are frequency dependent in the range of 1.5Hz-9Hz. Frequency dependent relations are estimated as Q α = 52f 1.03, Q β = 98f 1.07 and Q c = 158f 0.97.Q c estimates lie in between the values of Q i and Qs but closer to Q i at all central frequencies. Comparison between Q i and Q s shows that intrinsic absorption is predominant over scattering for Delhi and surrounding region.