Simulation of near fault ground motion in Delhi region

Abstract

Ground motions in the vicinity of the source caused severe damage to structures as evidenced during the past earthquakes (Loma Prieta 1989; Kobe 1995; Chi-Chi 1999). Near fault ground motions are characterized by long period velocity pulse as reported in literature (Somerville, 2005). This pulse type of motion is produced due to forward directivity where fault rupture propagates towards the site at a velocity close to shear wave velocity, causing most of the seismic energy to arrive at the site within a short time. Such impulsive motion subjects structures to high input seismic energy at the beginning of the record. In this study, near fault ground motion for Mw 6.0 has been simulated in Delhi region. The high frequency ground motion has been simulated using specific barrier model, combined with long period velocity pulse. As reported in literature, strong ground motion with long period pulse can increase the demand on medium and high rise structures.