time-frequency analysis of the 2017 sarpol-e zahab earthquake ground motions

a severe earthquake ground motion with moment magnitude mw=7.3 took place in the western part of iran on 12th november 2017. the aim of this proposed study is to assess the time evolution of the frequency-intensity content of sarpol-e zahab earthquake ground motions records by using of the wavelet transform (wt) methodology. for this purpose, the ground motions recorded at sarpol-e-zahab, kerend and javanrod stations that has maximum pga has been selected. time–frequency analysis of ground-motions recorded at the sarpol-e zahab station shows that the most energy content of the t component is concentrated at time equal to 21 s but is distributed over a range of periods between (0.2 -0.5sec) with a lesser peak in energy at a period of about 0.6 sec, that there may be effect of moving resonance on building with periods between (0.2-0.5 sec). also, it can be observed that most energy of the l component was highly concentrated at time equal to 21 s and a narrow period band (between 0.2 and 0.3 sec) that is considered as pulse like. this finding is consistent with damage observation in sarpol-e-zahab and it’s around villages where many dwellings and buildings which collapsed or suffered severe damage during this event had low fundamental period between (0.2-0.5sec).