Site amplification and resonance frequency in the urban environment

The effects of the built environment on site amplification and resonance frequency are studied utilizing 34 earthquake recordings made at three seismic downhole arrays (ATK, FTH and ZYT) and two outcrop stations at Istanbul. The earthquake data set included minor to moderate earthquakes having hypocenters at various distances and azimuths with respect to the arrays. The buildings considered in the study are at distances less than 110m from the arrays and have different dynamic characteristics. The results indicate the impact of the buildings on the site amplification and resonance frequency. At ATK and ZYT arrays, the buildings have a lowering effect on the site amplification, while at FTH array a shift in the resonance frequency is observed. Results from ATK and FTH sites also support previous findings that even in case of similarity between the shear wave velocity profiles amplification levels can differ significantly.