Interpretations of ground motion records from the 2017 Mw 7.3 Ezgeleh earthquake in Iran

Abstract

This study examines the time and frequency features of strong motion records obtained during the 12th November 2017 Mw 7.3 Ezgeleh (Iran) Earthquake. Different parameters including peak ground acceleration (PGA), peak ground velocity (PGV), spectral acceleration, significant duration, Arias intensity and Fourier amplitude are illustrated to provide a clear view on main characteristics of this event. As an important finding, a broad-band frequency content characteristic is obvious from the analysis of Fourier amplitude spectra obtained at four closest stations records. According to the results, the record obtained at Sarpol-e Zahab station could be considered as near-fault pulse-like motion. The amount of input energy and its corresponding level of frequency are discussed based on wavelet analysis. Results showed that more than 50% of earthquake energy at Sarpol-e Zahab city has been concentrated around 0.45 s which is close to the natural vibration period of low-to mid rise structures in the region. Finally, seismic intensity in terms of modified Mercalli intensity was extracted based on the Fourier spectrum amplitude and the peak ground motion parameters (PGA, PGV) in Sarpol-e Zahab city which was the worst affected area.