Trans-Boundary Earthquakes of the Himalayan Thrust Region and Their Bearing on Hazard Potential in Around Geographical Boundaries

Date: 4/24/2019

Time: 06:00 PM

Room: Grand Ballroom

2015 Nepal Earthquake (M_w 7.9) and 2009 Bhutan Earthquake (M_w 6.1) along with their prominent aftershocks have been studied to understand the degree of hazard potential in around border areas of India to Bhutan and Nepal. The ground motions of the 2015 Nepal Earthquake (M_w 7.9) showed a conspicuous process associated with non-linearity besides the proximity of the sites located on the sediments of Indo-Gangetic planes. We considered the detailed heterogeneity, medium of propagation, and rupture characteristics of the earthquakes to arrive at better explanation of trans-boundary earthquakes. We found that the horizontal components of all magnitudes (M_w ≥ 6.1) show peak pseudo-velocity responses at periods of 0.4 s to 0.6 s. The large elastic pseudo-velocity responses range between 20 cm/s and 45 cm/s at 5 % critical damping using data of Nepal earthquake sequence recorded in the Indo-Gangetic planes whilst low values less than 10 cm/s for pseudo-velocity responses were found for 2009 Bhutan earthquake (M_w 6.1). A comparison of the observational data with Ground Motion Prediction Equation (GMPE) for Himalaya demonstrated a close similarity. The observed peak ground accelerations and peak ground velocities at the various sites are generally well described by the GMPEs for trans-boundary earthquakes of Himalaya. It is also revealed that the basin sediments of Indo-Gangetic planes and Brahamputra valley are strongly amplified by the long-period components of the ground motions of the main shocks and their prominent aftershocks used in the present study. We infer that our findings are important for estimating the seismic hazard potential of the trans-boundary region having no constraints on geographical boundaries in around source zones of two prominent earthquakes of 2009 Bhutan earthquake (M_w 6.1) and 2015 Nepal earthquake (M_w 7.9) which, can also be utilised in the engineering practices for better structural resiliency of the region.

Presenting Author: Babita Sharma

Authors