Abdolhossein Fallahi; Meghdad Samaei; Jafar Karashi
Abstract
In the current study, using microtremor measurements at 15 stations of strong ground motion network in North-western Iran, dominant frequency is determined and sites are categorized. After correction of raw data, horizontal to vertical spectral ratio is calculated and the frequency corresponding to the ...
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In the current study, using microtremor measurements at 15 stations of strong ground motion network in North-western Iran, dominant frequency is determined and sites are categorized. After correction of raw data, horizontal to vertical spectral ratio is calculated and the frequency corresponding to the greatest amplitude is acknowledged as the dominant frequency. Also at 11 stations with good quality of recorded microtremors, horizontal to vertical ratio of earthquake motion is calculated. Agreement between these two spectral ratios is quite satisfactory. Maximum and minimum observed dominant frequencies are 1.72 and 7.34 respectively. Correspondingly, using past studies, shear wave at the top 30 m ( ) is estimated and based on different seismic codes, sites are categorized. If the categorization based on predominant frequency is compared with categorization based on reported by building and housing research center, dramatic differences will be observed. These differences could be attributed to uncertainties in reported Vs30 as well as estimated dominant frequencies.
