Empirical equations for the prediction of the bracketed and uniform duration of earthquake ground motion using the Iran database

Abstract

This study presents new empirical prediction equations for a number of bracketed and uniform durations using the Iranian strong ground motion database of accelerograms for the shallow crustal earthquakes until 2018. The database includes 1147 records of 213 earthquake events with the magnitudes from 5.0 to 7.8 and rupture distances from 2 to 600 km. The functional form of the model is an additive natural logarithm of four prediction variables, namely moment magnitude (Mw), rupture distance (Rrup), average shear wave velocity in the top 30 m (VS30), and faulting mechanism. The analysis of residuals was done for the both variables MW and Rrup and showed that the more the acceleration threshold, the less the range of residuals. The models were compared with existing duration prediction relations. The presented relations were developed in a wider range of acceleration thresholds (from 0.05 to 0.3 g with interval of 0.05) and resulted using Iranian strong ground motion database. The accuracy of the proposed model for the acceleration thresholds that have already been published showed lower standard deviations for the Iranian dataset.