Detailed Attenuation Study of Shear Waves in the Kumaon Himalaya, India, Using the Inversion of Strong-Motion Data

The frequency-dependent shear-wave quality factor Q(beta)(f) of the seismically active Kumaon Himalaya was calculated using strong-motion data recorded between 2006 and 2012. The inversion algorithm of strong-motion data, developed here, simultaneously gives the shear-wave quality factor and the site effect for each earthquake. The site effects obtained from the present inversion are within the standard limit of error and agree with those obtained through the H/V technique (H/V being the ratio of the Fourier spectra of the horizontal and vertical components of the record). The Q(beta)(f) values (in which Q(beta) is shear-wave quality factor and f is frequency) at different stations were computed using both the north-south and east-west components of acceleration records. The Q(beta)(f) values obtained from both components at 16 stations in the Kumaon Himalaya were used to compute a regional Q(f) relationship having the form Q(beta)(f) = (28 +/- 2.0)f ((1.2 +/- 0.07)). This Q(f) relationship suggests a low Q(0) value (< 200) and a high n value (> 0.8) for tectonically and seismically active regions.