Ground motion parameters for the 2015 Nepal Earthquake and its aftershocks

The 25th April 2015 Nepal earthquake was the first major event in the Himalayan orogeny to provide a relatively well-recorded dataset. This paper presents a comprehensive analysis of the mainshock and its five major aftershocks through 21 well-established ground motion parameters. The analysis is presented for near-field stations of the Kathmandu basin and far-field stations of the Indo-Ganga Plains, including the site response behavior with varying sediment depths. Moreover, Hilbert–Huang Transform is used to study site amplifications associated with sediment depth and soil class, especially at long periods. In addition, a new ground motion model (GMM) is derived for all 21 parameters using moment magnitude, source-to-site distance, site class and sediment depth as predictor variables. Further, to ensure that the developed GMM is not biased, an inter-event and intra-event residual analysis is performed. Furthermore, the GMM is compared with other well-established prediction models applicable to the study region. The efficacy of the current model is further addressed by the evaluation of ranking indices.