Determination of Shear Wave Velocity of Sedimentary Deposits by Means of Microtremor Measurements

This paper aims to study the possible use of micro tremor measurements for determination of shear wave velocity (Vs) profile of sedimentary deposits. For this purpose a series of micro tremor measurements have been conducted in Bam city (southeast of Iran). Micro tremor measurements included both one-point and array observations. The F-K spectrum analysis of micro tremors was used for determination of dispersion characteristics of micro tremors. Shear wave velocity profiles were then determined by using an inversion process. Ultimately, inverted Vs profiles were compared with other available Vs data in Bam city. The inverted profiles were reasonably in agreement with results of seismic refraction and down-hole methods. This shows that micro tremor array measurements are useful as a simple and economical method for Vs profiling. In addition, it was revealed that micro tremor method is capable of detecting the probable soft layer that underlies a stiff layer which seismic refraction cannot resolve.