Alternate method to develop ground motion prediction equations: calibration over Himalayan region

Abstract

An alternative approach for constructing GMPEs, the Consistent Spectral Shape approach (CSS), is recently proposed to overcome the limitations of the conventional methods. The CSS framework is already implemented using the NGA-West2 database to develop a set of five GMPEs of 5% damped spectral accelerations (RotD50, RotD100, Geo-mean, GMRotD50, and GMRotD100). In this paper, the performance of the CSS-GMPEs based on the NGA-West2 database is first assessed against those developed in the NGA-West2 project. Two different yardsticks are considered for the comparison: overall root mean square error (RMSE) and similitude of spectral shape. RMSE for CSS-GMPE and five NGA-West2 GMPEs are nearly consistent, but CSS utilizes a significantly smaller number of independent variables. CSS-GMPE also performs better while comparing the similitude of spectral shape. This paper next modifies the existing set of five CSS-GMPEs for the Himalayan region using a generic modification function contingent on intensity measure (RotD50, RotD100, Geo-mean, GMRotD50, and GMRotD100). All five CSS-GMPEs modified for the Himalayan region are observed to be performed satisfactorily for all practical purposes. These modified GMPEs are expected to be a valuable tool for site-specific seismic hazard analysis.