site effects using hvsr and ssr techniques in ramsar city

Over the last century, a lot of cities have expanded dramatically and specialists expect a similar trend for at least the next decades. in many parts of iran, urban areas are usually built on soft sediments. because this vast country is a part of alpine-himalayan seismic belt, so not only urban, but countryside and villages are also prone to strong ground shaking. the surface of the earth is always in vibration, even without earthquake. the vibrations at low seismic frequencies called“microtremors”, exist everywhere. site responses computed for a large number of events, allows to define unknown source position and plausible mechanism of the future ground motions. one way that is based on ambient vibrations are the h/vmethod of nakamura (1989), has been proven to be a convenient technique to estimate the fundamental frequency of soft deposits. this method is based on the fourier spectral ratio of the horizontal and vertical components of seismic noise wavefield.