Earthquake ground motion predictive equations for Garhwal Himalaya, India

Abstract

Predictive equations based on the stochastic approach are developed for earthquake ground motions from Garhwal Himalayan earthquakes of 3.5≤Mw≤6.8 at a distance of 10≤R≤250km. The predicted ground motion parameters are response spectral values at frequencies from 0.25 to 20Hz, and peak ground acceleration (PGA). The ground motion prediction equations (GMPEs) are derived from an empirically based stochastic ground motion model. The GMPEs show a fair agreement with the empirically developed ground motion equations from Himalaya as well as the NGA equation. The proposed relations also reasonably predict the observed ground motion of two major Himalayan earthquakes from Garhwal Himalayan region. For high magnitudes, there is insufficient data to satisfactorily judge the relationship; however it reasonably predicts the 1991 Uttarkashi earthquake (Mw=6.8) and 1999 Chamoli earthquake (Mw=6.4) from Garhwal Himalaya region.