The representability of attenuation characteristics of strong ground motions observed in the 1986 Dharmsala and 1991 Uttarkashi earthquakes by available empirical relations

The attenuation characteristics of the observed peak accelerations as a function of distance and magnitude for the 1986 Dharmsala (m(b) 5.5) and the 1991 Uttarkashi (m(b) 6.5) earthquakes have been compared with the empirical relations for various regions of the world. The relation of Abrahamson and Litehiser obtained using a world-wide data set, is found to be capable of predicting the Uttarkashi acceleration data and that of Peng et al. for China describes the Dharmsala data set quite well up to a distance of 24 km. Thus, the above two adjacent regions in Himalaya are characterized by different attenuation properties which are a reflection of the nature of the upper crustal rocks present in the respective regions.