Ground Motion Models for Non-Spectral Intensity Measures Based on the Iranian Database

An Iranian earthquake database has been employed to propose local empirical equations to predict non-spectral ground motion intensity measures, including Arias intensity, cumulative absolute velocity and duration of ground motions. The significant duration models have been considered 5% – 75% and 5% – 95% of Arias intensity in analyses. The bracketed and uniform duration models were proposed for absolute or relative acceleration thresholds, including 0.025g, 0.05g, 0.1g 0.025PGA, 0.05PGA and 0.1PGA. In this study, we used an updated dataset consisting of 2965 three-component time histories from 654 seismic events with the magnitude range 3.5 to 7.7 at distances less than 300 km recorded between 1975 and 2019. The functional form of the proposed models consists of some variables, including moment magnitude (Mw), Joyner-Boore distance (RJB), average velocity of shear waves for the upper 30-m depth (Vs30), and faulting mechanisms. The random-effects algorithm is used for conducting the regression analysis, which considers inter-event and intra-event error terms, separately. To verify the trend of attenuation in the proposed models, some comparisons have been made between the proposed models in the current study and those developed for other similar regions.